Witaj! To był pierwszy z Twoich filmów, który przypadkiem dziś znalazłem (uważnie obejrzałem kilka). "Problem jest taki, że nikt już nie wie jak pracować przy tych samochodach. Dzisiejsi mechanicy nie mają szkoleń z naprawiania samochodów z lat 80-tych i trudno znaleźć kogoś, kto by sobie z tym poradził, trzeba porzucić samochód bo nikt się na tym nie zna a jeśli już, to jest 1000 mil stąd"... 1000 ?! :)) Bardzo ciekawy, przystępny i edukacyjny kanał, gratuluję! - pomimo niemal 30-tu lat w zawodzie (diagnostyka silników i systemów sterowania) nie raz jeszcze tutaj zajrzę, wszak człowiek uczy się całe życie... dziękuję, łączę serdeczne pozdrowienia z Polski !! :)
Good information and advice. One of the first purchases I made when I acquired my 1991 Firebird Formula was a GM Service Manual off of Ebay and it has been incredibly valuable when trying to figure a number of problems, as well as getting the correct torque values for various fasteners and bolts. I've even sat down in some evenings just thumbing through various procedures in the manual, just to get myself more familiar with the car. I think people shy away from these TPI cars because they don't fully understand the TPI system itself, and the OBD1 controls. But, once you get your mind wrapped around it, they are incredibly simplistic compared to today's cars, but as you highlighted, you still have to have a good mechanical knowledge of how the engine works. Thanks for taking the time to put this video together.
Great video! For my ‘82 Corvette I use a free tool called WinALDL, runs on my laptop. Needs a cable that if you’re handy you can make one but I just bought one from OBD Diagnostics for about $60. Allows me to see in real time what the ECM is seeing. Was key to helping me find a bad IAC. Thanks for sharing your experience and knowledge.
Thank you! I appreciate your comment and suggestion. I do know about the cables and laptop software. It's on my list of future things to do. For most people the self contained scan tool is probably easier, but I haven't gone through the process with laptop system yet to compare.
Just a question for you. Which interface are you using on your laptop? Are you using an older style serial port or a USB? As I was looking at cables, there is a choice, and I saw a suggestion that it might be better to use an older operating system and the old serial port rather than USB and Windows 10 when using WINALDL.
@@bitsofwisdom460 I use a usb cable, windows 10 and WinALDL. The only hiccup was I had to give WinALDL permission to write to the hard drive to record data.
@@steveo170 Thank you! That's excellent. When I was working with the factory calibration teams, they often used older operating systems for long after everyone else upgraded due to the special needs of the controller tools.
Just ordered the service-manual and electrical diagnostics-supplement from your buddy at Books4Cars as well as an obd1 to Usb-connector so that I can record and datalog what's going on with my 87 iroc. Perhaps this is what I need to fix my random missing and sputtering at idle and around 1800-2000 rpm at part-throttle cruising. Runs like a champ when "beans are given". Looking forward to not just rely on TH-cam and old forum-posts haha. Awesome video, best in-depth description I've seen. Thank you so much, looking forward to future videos man!
Thanks very much! It sounds like you have what you need to dig in and investigate. One of the challenges is that at WOT, the mixture is fairly rich--"power enrichment". That mixture is easier to ignite with a spark. When you're at part or closed throttle and leaner, it can be harder to get good combustion. And the challenge in that is it can be either ignition or inconsistent fuel / air mixture that makes it harder to diagnose. I may have said this before, but long ago I was told: "If you think it is fuel, look at ignition and if you think it is ignition, look at fuel". That was on carbureted engines, but the thought still holds true today. A weak spark can imitate a bad fuel mixture and vice versa. I've lived that one several times in my life. In the extreme: "Wow, the plugs are wet fouled, is there too much fuel or are they just not firing".
@@bitsofwisdom460 Ah yes, I remember you said so in the video; about WOT compared to partially closed/open throttle. Ordered a cheap fuel-pressure tester-kit from Ebay some time ago because I've been thinking about fuel-pressure and such. All ignition-parts are new/fairly new. Coil, plugs, plug-wires, entire distributor, ICM and so forth. Ac delco r43ts - plugs, Iac, tps. Car hasn't been running long enough to get a good reading on the plugs. I've changed the plugs thrice. The ones I got out now was in for about a season or two. Haven't been driven too much Looking forward to seeing what's going on. If Tunerpro can't see what some of the sensors are doing, then it might just be a bad plug or connector that I've missed out on. I know the iac-connector is not looking too good, for one.
Great information. Wish I was your neighbor a few years back. I do have the GM manual and it is definitely a must as you mentioned. My only problem is it has a problem passing California smog do to high NOx. The parameters [ goal posts] seem to be pushed back every year and the car was not designed for the limits now enforced. I've done all the system checks that have to do with high NOx and all is functioning. Extreamly aggravating. I even played with the timing all the way to zero and still no luck.
Mike, I'm not familiar with the specifics of what California requires these days, but I am certainly familiar with the strictness of their approach. I presume that for NOx, they must have you running a dyno test of some sort to get it under load. I don't know what all you have done, and all of your vehicle's details, but I believe you have been thorough and I understand the frustration. I'll try to give you some thought starters, but you may have already been through these and they may or may not help. First, I think you're on the right track with timing retard, but you may not be seeing as much benefit as you would think. I believe that NOx should come down with retard, but our engines have electronic spark control. I don't know the algorithm that they are using, but it might have some regions where it is advancing spark until the knock sensor limits you. Or conversely, the curve is just designed to be aggressive up to the knock limit. IF that is the case, you could retard the initial and and not get as much benefit as you might think. And if that's the case, I'm not sure how to compensate (low octane fuel?? greater retard?). NOx control is two parts, first is engine out (mostly EGR) and second is catalyst. I know that even though the EGR passes all tests, you could still have an issue. The OBD1 tests are fairly coarse and might not pick up reduced flow due to EGR valve calibration or restriction in manifold passages or even something in the valve. A small leak in the diaphragm could also reduce flow. Also, most EGR valves do have a feature that makes them sensitive to backpressure, and they adjust their regulation based on that exhaust pressure. Finally, the catalysts do reduce efficiency with age; it is possible that your cat could be reduced beyond that.
Thanks so much for your time! I have lastly replaced the original 02 sensor. I did put a new exhaust system from stock. It's a GMMG chambered exhaust. Possibly affecting the back pressure? It's just a cat back system. Car runs cool while moving but does climb up a bit at idle until fan kicks on at 180° If I remove the belt on the air pump, the NOx is well within limit but then the other perameters exceed.... Wish I could find the balance. Even thought of partially blocking the air pump flow lines somehow to adjust NOx with CO and HC in limits.
Ah, Dan, now you've touched on something I've had to work the most on - with my 3rd gen camaro. The ECM and the PROM chip. When I bought my car, the guy I bought it from had run a wire from the cooling fan into the dashboard with a switch so he could manually switch on and off the cooling fan (due to overheating when stationary). I quickly took to youtube to find if others were having similar issues. Turns out, the cooling fan not coming on often enough in these older 3rd gens is a common problem - since the cars were meant to run at 240 degrees instead of 180 anyway. When these ecm's age, my guess is that the ecm board and capacitors and resistors don't resist and capacitate and amp as they used to -- causing the fan to turn on way later than it did when the car was new. (Yes, before this Hypothesis, I DID change every temp sensor in the car with NOS ACDelco replacement sensors - first!) Well to most of us, we want to cars running in the 180 - 200 range instead of the high 240 anyway, so with the help of this site: www.thirdgen.org/technical-articles, I was able to learn how the factory proms are programmable once you find the right decoder to decode the particular chip you have and interpret it with a some free or cheap downloadable support sites. To make a long story short, it was awesome, I was able to copy my original prom with a usb chip burner (generic one off of ebay not a gm thing) and I can take a copy of my original chip program, modify the copy, change the "Fan ON" temp and "Fan OFF" temp, and as of last summer I did all that and used the original chip reprogrammed to turn the fan on and off inline with keeping the car at 190 degrees to 200, instead of the factory wild high 240. It was an engineering technology major's dream! I loved it. My car runs just fine at 180 - 200 instead of the ridiculous factory 240, and its all done the right way, instead of a wire hanging from the dash!
That sounds great! It's good that you were able to navigate the PROM burning process. I may get there at some point, I have just been working through the other areas first. Mine seems to be working to about the 220 mark yet, but I wouldn't mind bringing it down a little. Given my previous experience in the business, I suspect that the motivation for the higher fan point may have been related to regulatory needs. The emissions and fuel economy team may have wanted to be sure that the fans stayed off during the certification process on the chassis dyno. The electric fans draw 12v power and it will reduce fuel economy some amount. Every little bit counts when you're trying to meet targets. Regarding aged electronics, there are many possibilities, but the most critical parts are usually electrolytic capacitors. They can age just sitting on the shelf. I was concerned about mine that didn't run for 25+ years, yet so far it has been ok.
@@bitsofwisdom460 Yeah 220° is good but my fan would not kick on till 240+. As far as your idea why they ran it at 220, I myself guessed it was to help the catalytic converter burn off unburnt fuel for emissions, so Your theory is good
Thank you sir for sharing your OBD1 knowledge with us. I've got 5 GM vehicles 1988 - 1994. I have the service manuals and parts books for them. Those have been helpful through out the years. However, some of it I do not fully understand. I'm trying to learn on my own. I've been able to fix things. I've use Tunerpro RT to trace down a couple problems in the passed. A couple days ago one of my cars (1992 Cavalier Z24) had a crank no start, no MIL, no prime with key on RUN , ACC and starter works. (Thank God the failure was in the driveway) I'm trying to correctly understand the information to diagnose the problem. I'm not going to throw parts at it in 'hopes' I hit on the correct issue. I do have a new ignition switch and will try it. I'm hoping it isn't the ECM.
If you have the book, I would start with the engine emission section. Should be section 6E2 and Chart A3 "Engine Cranks but won't run". Make sure it flashes a code 12, that means ECM is up and running. If you can't hear fuel pump prime on initial key up, that's a problem. You can check fuel pressure. May need to check for spark. If you have Tuner Pro RT, you can do a check of sensors with the engine off to see if something looks off. The trouble trees should walk you through the basics.
@@bitsofwisdom460 Thank you for the suggestions. I have looked over the trouble shooting section. With the key ON, nothing happens. No lights on the panel. No fuel prime. No pressure at the rail. I'm going to install the new ignition switch I have this afternoon when I get home from work. I don't think I'll be able to get any data from Tuner pro if the ignition switch isn't turning on the SEL or priming the pump. Paper clip trick won't work either, if there is no power to the switch.
Yes, I understand and you're correct. If the issue is that you have no power coming up with ignition, then that is a different path. If you can crank, then you have battery power to the solenoid and to the start contacts in the ignition switch. I would go back to section 8 in wiring to look at the power distribution. Most of those power feeds either have a fuse or a fusible link wire. May need to check those with a voltmeter to be sure you have power to all the right switch contacts.
Yes, it is quite possible that the module is the cause, but it could be a number of other things. I am working on a follow-up video on diagnostics with a focus on no start / hard to start. It will probably be a few days before I am done, but it can provide some additional assistance.
I have a 1992 Buick Regal it was my granma car was hardly ever drove but now I drive it all the time so it's always haveing issues I need a scanner for it .
Hey any idea on what to check if a 1989 Chevrolet Camaro tbi oxygen sensor signal wire got cut while driving , been tryint to figure out if it shorted something out , did a resistance and continuity test with a volt and it beeped as working
Damage to the wire for the oxygen sensor can be a problem. Some of them actually use the wire as a sort of vent to atmosphere for reference. Also, its operating voltage and current are very low, so it is sensitive to wiring issues. The challenge with testing an O2 sensor is that it doesn't work when it is cold, so standard tests with a voltmeter / ohmmeter aren't accurate. When it is hot, it produces a voltage based on the oxygen content around the element in the exhaust. The PCM / ECM will supply a reference voltage around 0.45 Volts for when the system is cold. In short, the OBD1 diagnostic ought to pick up a problem and give you a MIL light if the sensor is malfunctioning, but the diagnostic may take a lot of driving before it picks it up. A scan tool is the best to see if the system goes into closed loop and you can read cross counts and live O2 voltage. You can also put a voltmeter on the computer terminals for the sensor and read the voltage live with the engine running. I had a bad sensor early on with my Camaro and had to find a bench test method to test a sensor. See this video: th-cam.com/video/lG7knaBmu0s/w-d-xo.html
@@bitsofwisdom460 thx my my dmv reads about .396 when back proing the O2 sensor signal wire, can the voltage be off that much? I believe replacing the whole wire would fix my problem
Definitely will invest in a scan tool I checked the voltage while the car was running and it stayed in between like 7-8 millivolts only went down when I put my foot on the gas, not sure if it should stay at 7-8 like that also I was getting a reading of the same voltage when I first started the car on a cold engine which is weird being that it takes few minutes for the ecm to use the oxygen sensor
Since the O2 sensor wire was cut while driving would that have shorted something out like the ecm or O2 signal wire , had already replaced the oxygen sensor and crimped the new connector back on the oxygen sensor connector after the problem occured, really only thing I haven't fully replaced is the full wire itself , replaced the ecm also and still getting same problem where the car stalls intermittently
@@The1972Cutlass With a standard non-heated (single wire) sensor, the ECM should provide about .400 to .500 V engine off. With the engine running and sensor hot (5 minutes) voltage will oscillate between 0.100 and 0.900 as the engine runs in closed loop. Lower than roughly 0.450 is lean and higher than that is rich. Not sure which wire is is damaged- sensor or engine harness side. Engine harness should be repairable. If the connector is damaged, I would buy a pre-made pigtail and splice to the harness. O2 sensor wire, if operation is abnormal, I would be inclined to replace the sensor.
@@bitsofwisdom460 Bought me a obd1 Ford Taurus Shop Manual today! We have a 94 Ford Taurus - with no youtube support on that model I had to go to the manual
O ok i tested the map sensor disconnected, had same readings and didnt notice a change how do i test the tps to see if working properly, isn't there a ground circuit on the back of one of the cylinder heads, i heard its hard to get too
TPS normally takes either a scan tool or a set of jumper wires that match the pins. My '85 has weatherpack and I have a set of three wires that I assembled and can put between the TPS and the harness connector that the meter can clip to. There are normally ground connections on the back of both cylinder heads. I'm not sure where your distributor harness grounds, I would track it back from the cap.
@@bitsofwisdom460 o ok I was reading my service manual and it says ecm supplies voltage of about .45 between d7 and d6 I tested the signal wire came up to about .40 the d6 wire says o2 ground circuit should that read about .45 as stated in the manual?
@@The1972Cutlass 0.40 is within range for a check with ignition on and engine stopped. I would also check from each of those pins to good chassis ground as double check. Main thing is to be sure ground side is zero to chassis ground.
@@The1972Cutlass A scanner is a great help. I have done considerable diagnosis with a digital meter, but a scanner lets you see multiple parameters at one time and many times that makes it easier to find the problem
O ok I purchased the Delphi oxygen sensor connector before says fits 88-92 Camaro tbi, for some reason I suspect it's the oxygen sensor connector not being crimped and sealed right because the car was running great until the wire was severed so u believe even tho it was cut while driving it wouldn't have not shorted anything else out like maf or tps sensor
A good crimp is critical, sealing is for longer term protection so it doesn't get wet and corroded. My suggestion for a pigtail is to be sure you have a good crimp. You could try soldering the current crimp to see if it helps. Flowing solder into the joint will improve the connection. It is also possible that you have a bad or damaged sensor. I had a bad Delphi sensor with only a few miles on it. That's why I tested it with a torch in that video. They are sensitive and can be easily damaged.
@@bitsofwisdom460 o ok appreciate that I'll return the sensor since. I have a warranty, do u recommend heat shrink tube I already have those, kinda worried about soldering since I never have before
@@The1972Cutlass If the wires and connector are clean with no corrosion, a solid crimp should work without solder. Shrink tubing is good, but in the short term, if the wiring connection is dry and clean, it should work. The shrink tubing is to keep it that way. What to think about with o2 sensor connections is that because the voltage and current are so low, there isn't much power to "jump" a loose or contaminated connection. A 12v connection with an amp of current will arc very nicely across a marginal connection. An O2 sensor at 0.1 volt and microamps can't do that. By the way, you mentioned running at 700 mv earlier. If the system is holding consistently there, it indicates a rich condition, as in closed loop it ought to switch back and forth low to high.
@@bitsofwisdom460 o ok yea I thought it was abnormal to stay around that voltage without going back and forth from 100 to 999 mv, yea I kinda hate that it had to be the O2 sensor as opposed to other sensors that aren't so critical on the voltage being so low that it isn't to much room for error
Also forgot to ask is it normal to get a reading from the O2 sensor soon as the car is stated, I decided to use the voltmeter to it soon as it started and that's when I got the 700 mv all the way through closed loop
I would consider it depending on the distance. Sometimes we're talking 1000 or 2000 miles. I do welcome questions and comments and if I can answer / video for the channel, that is my first choice.
The purpose of the ground wires and pins is to take the voltage to zero. If there is a lot of current on a long wire, there can be a very low voltage due to resistance losses. If there is no / low current it should be zero. Even if the ECM is not programmed, zero would be zero If it is not, there is a problem with the ground connections. The ECM could try really hard to put power on that pin, but a good ground will still take it to zero. If you transferred the PROM to this ECM from the previous one, it should work.
Nice to see another video,sadly no time to watch whole thing this morning, will finish it tonight. Have an update Im downloading on this winters work on our Formula, I do a little each year. Once I get this back together I have a question about plug gapping. I changed them during summer and gapped to manufaturer specs, cant rmember what it was, the plugs I took out burned lean. Recently saw someone mention gap should be .45 with the hypertech chip setup, mine has had this chip previously installed. Car runs and idles great except the sticking idle we discussed before and I believe I nipped that in the bud, total cleanup of throttle body. It of course needs valve guides so she does a little puffing on startup but doesnt seem to be running to rich or lean other then plugs. If you dont miind will share a link later to where I am on rig.
My 1985 has a label indicating there was a service campaign that changed the plug gap to 0.035. I looked up the number (85-C-22) and it indicated that in 1984 and 1985 several V8 engines (L69, LB9, L98) in Camaro, Corvette and Monte Carlo had performance degradation over time due to misfire. The campaign was to replace the coil, ignition module, and then regap plugs to 0.035. I don't know if that carried over into other model years. HEI ignition usually ran higher gaps, but that will lead to higher voltages required to jump the gap and apparently it was too much. I haven't read the plugs yet in my 305, but other GM engines that I had with closed loop systems tended to have the plugs running to the white side.
If you go to the "about" link on my channel home page, there is a place where you can select "email for business inquiries". I'm not a business at this point, but I do have an email posted there and you can send me a message. No promise that I can help, but I will take a look.
Witaj! To był pierwszy z Twoich filmów, który przypadkiem dziś znalazłem (uważnie obejrzałem kilka). "Problem jest taki, że nikt już nie wie jak pracować przy tych samochodach. Dzisiejsi mechanicy nie mają szkoleń z naprawiania samochodów z lat 80-tych i trudno znaleźć kogoś, kto by sobie z tym poradził, trzeba porzucić samochód bo nikt się na tym nie zna a jeśli już, to jest 1000 mil stąd"... 1000 ?! :)) Bardzo ciekawy, przystępny i edukacyjny kanał, gratuluję! - pomimo niemal 30-tu lat w zawodzie (diagnostyka silników i systemów sterowania) nie raz jeszcze tutaj zajrzę, wszak człowiek uczy się całe życie... dziękuję, łączę serdeczne pozdrowienia z Polski !! :)
Thank you for your kind remarks, it is much appreciated. Also, I thank the Google translator...
Good information and advice. One of the first purchases I made when I acquired my 1991 Firebird Formula was a GM Service Manual off of Ebay and it has been incredibly valuable when trying to figure a number of problems, as well as getting the correct torque values for various fasteners and bolts. I've even sat down in some evenings just thumbing through various procedures in the manual, just to get myself more familiar with the car.
I think people shy away from these TPI cars because they don't fully understand the TPI system itself, and the OBD1 controls. But, once you get your mind wrapped around it, they are incredibly simplistic compared to today's cars, but as you highlighted, you still have to have a good mechanical knowledge of how the engine works.
Thanks for taking the time to put this video together.
Thank you for your comments. I agree that the TPI isn't as complex as it seems at first look, and yes the factory manual is really essential.
Great video! For my ‘82 Corvette I use a free tool called WinALDL, runs on my laptop. Needs a cable that if you’re handy you can make one but I just bought one from OBD Diagnostics for about $60. Allows me to see in real time what the ECM is seeing. Was key to helping me find a bad IAC. Thanks for sharing your experience and knowledge.
Thank you! I appreciate your comment and suggestion. I do know about the cables and laptop software. It's on my list of future things to do. For most people the self contained scan tool is probably easier, but I haven't gone through the process with laptop system yet to compare.
Just a question for you. Which interface are you using on your laptop? Are you using an older style serial port or a USB? As I was looking at cables, there is a choice, and I saw a suggestion that it might be better to use an older operating system and the old serial port rather than USB and Windows 10 when using WINALDL.
@@bitsofwisdom460 I use a usb cable, windows 10 and WinALDL. The only hiccup was I had to give WinALDL permission to write to the hard drive to record data.
@@steveo170 Thank you! That's excellent. When I was working with the factory calibration teams, they often used older operating systems for long after everyone else upgraded due to the special needs of the controller tools.
Thanks for this video - I have my GM shop manual - it has bern great. Fixed a spun crank bearing with it!
You're welcome! The GM service engineers work very hard on those manuals to be sure they are thorough and correct.
@@bitsofwisdom460 Bought it on ebay like you said - wanted it to approach a complete restore to original camaro specs
Just ordered the service-manual and electrical diagnostics-supplement from your buddy at Books4Cars as well as an obd1 to Usb-connector so that I can record and datalog what's going on with my 87 iroc. Perhaps this is what I need to fix my random missing and sputtering at idle and around 1800-2000 rpm at part-throttle cruising. Runs like a champ when "beans are given".
Looking forward to not just rely on TH-cam and old forum-posts haha.
Awesome video, best in-depth description I've seen. Thank you so much, looking forward to future videos man!
Thanks very much! It sounds like you have what you need to dig in and investigate. One of the challenges is that at WOT, the mixture is fairly rich--"power enrichment". That mixture is easier to ignite with a spark. When you're at part or closed throttle and leaner, it can be harder to get good combustion. And the challenge in that is it can be either ignition or inconsistent fuel / air mixture that makes it harder to diagnose. I may have said this before, but long ago I was told: "If you think it is fuel, look at ignition and if you think it is ignition, look at fuel". That was on carbureted engines, but the thought still holds true today. A weak spark can imitate a bad fuel mixture and vice versa. I've lived that one several times in my life. In the extreme: "Wow, the plugs are wet fouled, is there too much fuel or are they just not firing".
@@bitsofwisdom460 Ah yes, I remember you said so in the video; about WOT compared to partially closed/open throttle.
Ordered a cheap fuel-pressure tester-kit from Ebay some time ago because I've been thinking about fuel-pressure and such. All ignition-parts are new/fairly new. Coil, plugs, plug-wires, entire distributor, ICM and so forth. Ac delco r43ts - plugs, Iac, tps. Car hasn't been running long enough to get a good reading on the plugs. I've changed the plugs thrice. The ones I got out now was in for about a season or two. Haven't been driven too much
Looking forward to seeing what's going on. If Tunerpro can't see what some of the sensors are doing, then it might just be a bad plug or connector that I've missed out on. I know the iac-connector is not looking too good, for one.
Great information. Wish I was your neighbor a few years back. I do have the GM manual and it is definitely a must as you mentioned. My only problem is it has a problem passing California smog do to high NOx. The parameters [ goal posts] seem to be pushed back every year and the car was not designed for the limits now enforced. I've done all the system checks that have to do with high NOx and all is functioning. Extreamly aggravating. I even played with the timing all the way to zero and still no luck.
Mike, I'm not familiar with the specifics of what California requires these days, but I am certainly familiar with the strictness of their approach. I presume that for NOx, they must have you running a dyno test of some sort to get it under load. I don't know what all you have done, and all of your vehicle's details, but I believe you have been thorough and I understand the frustration. I'll try to give you some thought starters, but you may have already been through these and they may or may not help. First, I think you're on the right track with timing retard, but you may not be seeing as much benefit as you would think. I believe that NOx should come down with retard, but our engines have electronic spark control. I don't know the algorithm that they are using, but it might have some regions where it is advancing spark until the knock sensor limits you. Or conversely, the curve is just designed to be aggressive up to the knock limit. IF that is the case, you could retard the initial and and not get as much benefit as you might think. And if that's the case, I'm not sure how to compensate (low octane fuel?? greater retard?). NOx control is two parts, first is engine out (mostly EGR) and second is catalyst. I know that even though the EGR passes all tests, you could still have an issue. The OBD1 tests are fairly coarse and might not pick up reduced flow due to EGR valve calibration or restriction in manifold passages or even something in the valve. A small leak in the diaphragm could also reduce flow. Also, most EGR valves do have a feature that makes them sensitive to backpressure, and they adjust their regulation based on that exhaust pressure. Finally, the catalysts do reduce efficiency with age; it is possible that your cat could be reduced beyond that.
Thanks so much for your time! I have lastly replaced the original 02 sensor. I did put a new exhaust system from stock. It's a GMMG chambered exhaust. Possibly affecting the back pressure? It's just a cat back system. Car runs cool while moving but does climb up a bit at idle until fan kicks on at 180° If I remove the belt on the air pump, the NOx is well within limit but then the other perameters exceed.... Wish I could find the balance. Even thought of partially blocking the air pump flow lines somehow to adjust NOx with CO and HC in limits.
Ah, Dan, now you've touched on something I've had to work the most on - with my 3rd gen camaro. The ECM and the PROM chip. When I bought my car, the guy I bought it from had run a wire from the cooling fan into the dashboard with a switch so he could manually switch on and off the cooling fan (due to overheating when stationary). I quickly took to youtube to find if others were having similar issues. Turns out, the cooling fan not coming on often enough in these older 3rd gens is a common problem - since the cars were meant to run at 240 degrees instead of 180 anyway. When these ecm's age, my guess is that the ecm board and capacitors and resistors don't resist and capacitate and amp as they used to -- causing the fan to turn on way later than it did when the car was new. (Yes, before this Hypothesis, I DID change every temp sensor in the car with NOS ACDelco replacement sensors - first!) Well to most of us, we want to cars running in the 180 - 200 range instead of the high 240 anyway, so with the help of this site: www.thirdgen.org/technical-articles, I was able to learn how the factory proms are programmable once you find the right decoder to decode the particular chip you have and interpret it with a some free or cheap downloadable support sites. To make a long story short, it was awesome, I was able to copy my original prom with a usb chip burner (generic one off of ebay not a gm thing) and I can take a copy of my original chip program, modify the copy, change the "Fan ON" temp and "Fan OFF" temp, and as of last summer I did all that and used the original chip reprogrammed to turn the fan on and off inline with keeping the car at 190 degrees to 200, instead of the factory wild high 240. It was an engineering technology major's dream! I loved it. My car runs just fine at 180 - 200 instead of the ridiculous factory 240, and its all done the right way, instead of a wire hanging from the dash!
That sounds great! It's good that you were able to navigate the PROM burning process. I may get there at some point, I have just been working through the other areas first. Mine seems to be working to about the 220 mark yet, but I wouldn't mind bringing it down a little. Given my previous experience in the business, I suspect that the motivation for the higher fan point may have been related to regulatory needs. The emissions and fuel economy team may have wanted to be sure that the fans stayed off during the certification process on the chassis dyno. The electric fans draw 12v power and it will reduce fuel economy some amount. Every little bit counts when you're trying to meet targets.
Regarding aged electronics, there are many possibilities, but the most critical parts are usually electrolytic capacitors. They can age just sitting on the shelf. I was concerned about mine that didn't run for 25+ years, yet so far it has been ok.
@@bitsofwisdom460 Yeah 220° is good but my fan would not kick on till 240+. As far as your idea why they ran it at 220, I myself guessed it was to help the catalytic converter burn off unburnt fuel for emissions, so Your theory is good
Thank you sir for sharing your OBD1 knowledge with us. I've got 5 GM vehicles 1988 - 1994. I have the service manuals and parts books for them. Those have been helpful through out the years. However, some of it I do not fully understand. I'm trying to learn on my own. I've been able to fix things. I've use Tunerpro RT to trace down a couple problems in the passed. A couple days ago one of my cars (1992 Cavalier Z24) had a crank no start, no MIL, no prime with key on RUN , ACC and starter works. (Thank God the failure was in the driveway) I'm trying to correctly understand the information to diagnose the problem. I'm not going to throw parts at it in 'hopes' I hit on the correct issue. I do have a new ignition switch and will try it. I'm hoping it isn't the ECM.
If you have the book, I would start with the engine emission section. Should be section 6E2 and Chart A3 "Engine Cranks but won't run". Make sure it flashes a code 12, that means ECM is up and running. If you can't hear fuel pump prime on initial key up, that's a problem. You can check fuel pressure. May need to check for spark. If you have Tuner Pro RT, you can do a check of sensors with the engine off to see if something looks off.
The trouble trees should walk you through the basics.
@@bitsofwisdom460 Thank you for the suggestions. I have looked over the trouble shooting section. With the key ON, nothing happens. No lights on the panel. No fuel prime. No pressure at the rail. I'm going to install the new ignition switch I have this afternoon when I get home from work. I don't think I'll be able to get any data from Tuner pro if the ignition switch isn't turning on the SEL or priming the pump. Paper clip trick won't work either, if there is no power to the switch.
Yes, I understand and you're correct. If the issue is that you have no power coming up with ignition, then that is a different path. If you can crank, then you have battery power to the solenoid and to the start contacts in the ignition switch. I would go back to section 8 in wiring to look at the power distribution. Most of those power feeds either have a fuse or a fusible link wire. May need to check those with a voltmeter to be sure you have power to all the right switch contacts.
I’d love to see a comprehensive diagnostic on cruise control on these cars.
Let me think about that one, might be a possibility.
@@bitsofwisdom460 I've been looking for 3 years, there's very little - if at all on the third gen f body.
What model of Actron scanner are you using? Very good info. Thanks!
It's a CP9690.
Could the Icm inside the distributor of my 305 tpi motor be going bad making it run one day and not the next day?
Yes, it is quite possible that the module is the cause, but it could be a number of other things.
I am working on a follow-up video on diagnostics with a focus on no start / hard to start. It will probably be a few days before I am done, but it can provide some additional assistance.
I have a 1992 Buick Regal it was my granma car was hardly ever drove but now I drive it all the time so it's always haveing issues I need a scanner for it .
Wow ob1 data is more rare than chicken lips. Good job
Thank you
Hey any idea on what to check if a 1989 Chevrolet Camaro tbi oxygen sensor signal wire got cut while driving , been tryint to figure out if it shorted something out , did a resistance and continuity test with a volt and it beeped as working
Damage to the wire for the oxygen sensor can be a problem. Some of them actually use the wire as a sort of vent to atmosphere for reference. Also, its operating voltage and current are very low, so it is sensitive to wiring issues. The challenge with testing an O2 sensor is that it doesn't work when it is cold, so standard tests with a voltmeter / ohmmeter aren't accurate. When it is hot, it produces a voltage based on the oxygen content around the element in the exhaust. The PCM / ECM will supply a reference voltage around 0.45 Volts for when the system is cold.
In short, the OBD1 diagnostic ought to pick up a problem and give you a MIL light if the sensor is malfunctioning, but the diagnostic may take a lot of driving before it picks it up. A scan tool is the best to see if the system goes into closed loop and you can read cross counts and live O2 voltage. You can also put a voltmeter on the computer terminals for the sensor and read the voltage live with the engine running.
I had a bad sensor early on with my Camaro and had to find a bench test method to test a sensor. See this video: th-cam.com/video/lG7knaBmu0s/w-d-xo.html
@@bitsofwisdom460 thx my my dmv reads about .396 when back proing the O2 sensor signal wire, can the voltage be off that much? I believe replacing the whole wire would fix my problem
Definitely will invest in a scan tool I checked the voltage while the car was running and it stayed in between like 7-8 millivolts only went down when I put my foot on the gas, not sure if it should stay at 7-8 like that also I was getting a reading of the same voltage when I first started the car on a cold engine which is weird being that it takes few minutes for the ecm to use the oxygen sensor
Since the O2 sensor wire was cut while driving would that have shorted something out like the ecm or O2 signal wire , had already replaced the oxygen sensor and crimped the new connector back on the oxygen sensor connector after the problem occured, really only thing I haven't fully replaced is the full wire itself , replaced the ecm also and still getting same problem where the car stalls intermittently
@@The1972Cutlass With a standard non-heated (single wire) sensor, the ECM should provide about .400 to .500 V engine off. With the engine running and sensor hot (5 minutes) voltage will oscillate between 0.100 and 0.900 as the engine runs in closed loop. Lower than roughly 0.450 is lean and higher than that is rich. Not sure which wire is is damaged- sensor or engine harness side. Engine harness should be repairable. If the connector is damaged, I would buy a pre-made pigtail and splice to the harness. O2 sensor wire, if operation is abnormal, I would be inclined to replace the sensor.
Can you post your friends car manual website?
books4cars.com
@@bitsofwisdom460 Bought me a obd1 Ford Taurus Shop Manual today! We have a 94 Ford Taurus - with no youtube support on that model I had to go to the manual
O ok i tested the map sensor disconnected, had same readings and didnt notice a change how do i test the tps to see if working properly, isn't there a ground circuit on the back of one of the cylinder heads, i heard its hard to get too
TPS normally takes either a scan tool or a set of jumper wires that match the pins. My '85 has weatherpack and I have a set of three wires that I assembled and can put between the TPS and the harness connector that the meter can clip to.
There are normally ground connections on the back of both cylinder heads. I'm not sure where your distributor harness grounds, I would track it back from the cap.
@@bitsofwisdom460 o ok I think I might just buy the scanner I feel it would lead me in a better direction since it shows live data
@@bitsofwisdom460 o ok I was reading my service manual and it says ecm supplies voltage of about .45 between d7 and d6 I tested the signal wire came up to about .40 the d6 wire says o2 ground circuit should that read about .45 as stated in the manual?
@@The1972Cutlass 0.40 is within range for a check with ignition on and engine stopped. I would also check from each of those pins to good chassis ground as double check. Main thing is to be sure ground side is zero to chassis ground.
@@The1972Cutlass A scanner is a great help. I have done considerable diagnosis with a digital meter, but a scanner lets you see multiple parameters at one time and many times that makes it easier to find the problem
O ok I purchased the Delphi oxygen sensor connector before says fits 88-92 Camaro tbi, for some reason I suspect it's the oxygen sensor connector not being crimped and sealed right because the car was running great until the wire was severed so u believe even tho it was cut while driving it wouldn't have not shorted anything else out like maf or tps sensor
A good crimp is critical, sealing is for longer term protection so it doesn't get wet and corroded. My suggestion for a pigtail is to be sure you have a good crimp. You could try soldering the current crimp to see if it helps. Flowing solder into the joint will improve the connection. It is also possible that you have a bad or damaged sensor. I had a bad Delphi sensor with only a few miles on it. That's why I tested it with a torch in that video. They are sensitive and can be easily damaged.
@@bitsofwisdom460 o ok appreciate that I'll return the sensor since. I have a warranty, do u recommend heat shrink tube I already have those, kinda worried about soldering since I never have before
@@The1972Cutlass If the wires and connector are clean with no corrosion, a solid crimp should work without solder. Shrink tubing is good, but in the short term, if the wiring connection is dry and clean, it should work. The shrink tubing is to keep it that way.
What to think about with o2 sensor connections is that because the voltage and current are so low, there isn't much power to "jump" a loose or contaminated connection. A 12v connection with an amp of current will arc very nicely across a marginal connection. An O2 sensor at 0.1 volt and microamps can't do that.
By the way, you mentioned running at 700 mv earlier. If the system is holding consistently there, it indicates a rich condition, as in closed loop it ought to switch back and forth low to high.
@@bitsofwisdom460 o ok yea I thought it was abnormal to stay around that voltage without going back and forth from 100 to 999 mv, yea I kinda hate that it had to be the O2 sensor as opposed to other sensors that aren't so critical on the voltage being so low that it isn't to much room for error
Also forgot to ask is it normal to get a reading from the O2 sensor soon as the car is stated, I decided to use the voltmeter to it soon as it started and that's when I got the 700 mv all the way through closed loop
You should go help him and record it for you channel.
I would consider it depending on the distance. Sometimes we're talking 1000 or 2000 miles. I do welcome questions and comments and if I can answer / video for the channel, that is my first choice.
I thought it could possibly give a false reading since it may not be programmed
The purpose of the ground wires and pins is to take the voltage to zero. If there is a lot of current on a long wire, there can be a very low voltage due to resistance losses. If there is no / low current it should be zero. Even if the ECM is not programmed, zero would be zero If it is not, there is a problem with the ground connections. The ECM could try really hard to put power on that pin, but a good ground will still take it to zero.
If you transferred the PROM to this ECM from the previous one, it should work.
@@bitsofwisdom460 o ok to check voltage ground black to negative battery and red to pin ?
@@The1972Cutlass yes, that is fine. If not zero, then need intermediate points to see where it is bad.
@@bitsofwisdom460 o ok do you recommend purchasing the power probe ect3000
Nice to see another video,sadly no time to watch whole thing this morning, will finish it tonight. Have an update Im downloading on this winters work on our Formula, I do a little each year. Once I get this back together I have a question about plug gapping. I changed them during summer and gapped to manufaturer specs, cant rmember what it was, the plugs I took out burned lean. Recently saw someone mention gap should be .45 with the hypertech chip setup, mine has had this chip previously installed. Car runs and idles great except the sticking idle we discussed before and I believe I nipped that in the bud, total cleanup of throttle body. It of course needs valve guides so she does a little puffing on startup but doesnt seem to be running to rich or lean other then plugs. If you dont miind will share a link later to where I am on rig.
My 1985 has a label indicating there was a service campaign that changed the plug gap to 0.035. I looked up the number (85-C-22) and it indicated that in 1984 and 1985 several V8 engines (L69, LB9, L98) in Camaro, Corvette and Monte Carlo had performance degradation over time due to misfire. The campaign was to replace the coil, ignition module, and then regap plugs to 0.035. I don't know if that carried over into other model years. HEI ignition usually ran higher gaps, but that will lead to higher voltages required to jump the gap and apparently it was too much. I haven't read the plugs yet in my 305, but other GM engines that I had with closed loop systems tended to have the plugs running to the white side.
Do you have an email I can contact you at. Wondering if you could give me any tips on a 1986 Cutlass AIR/Smog issue I’m having.
If you go to the "about" link on my channel home page, there is a place where you can select "email for business inquiries". I'm not a business at this point, but I do have an email posted there and you can send me a message. No promise that I can help, but I will take a look.