I have a 1994 pointiac firebird formula 5.7 litter V-8 automatic I'm not having this issue. But what i did like about your post. Is how your reading up on the information. Available to you. On air. Out loud. On air. I like this. It shows me that your doing your very best to find the problem. And then fixing it. And the fact. That your doing it . Right in front of us. And hands on. So we can understand why you did what your doing.and why your doing. That is such a wonderfull thing. Cause a lkt of people learn by reading. Whyile other leople learn hands on.so to make a long story shorter. I reall like your chanel. ❤❤❤❤
Might also want to check your harmonic balancer orientation as I recall they are weighted a certain way from the factory and the crank hub needs to be oriented correctly on the crank snout. Did also find a scenario in which the oil from a cheaper air filter kept coating the MAF sensor causing it to read wrong. Hope these help.
I have a 95 firebird, and after describing what the battery gauge did my mechanic told me “old cars are just like that”. It behaves exactly like yours does jumping up and down at idle, I’m so glad I found this video.
I work at Firestone and found this the other day on Mitchell... "Technical Service Bulletin Reference Number(s)02-06-05-004b Date of Issue: February 14 2006 Service Information General Motors Engineering, in an effort to determine the root cause of catalytic converter damage, has determined that aftermarket alarm systems incorrectly installed in vehicles have the potential to cause misfires codes and damage to the converter. These alarm systems use a circuit interrupt which utilizes the ignition circuit on the vehicles. These alarms systems utilize mechanical relays and normal vehicle movement can trigger these relays to engage and disengage the ignition circuit while the vehicle is in motion. These disruptions of the ignition circuit, which occur in milliseconds, may cause more fuel to be commanded. Over time, this dumping of fuel on and off again can cause misfire codes and ultimately damage the converter assembly............." May be applicable, may not.
Hi Biff, So first kudos on your patience/stubbornness;-) in continuing to pursue this misfire troubleshooting which you have been doing. I know I would’ve run out of patience a long time ago. So I had one experience that gave me a fit a few years ago On a V-8 suburban. I took it to the dealer since I really expected it to be something electrical since it had such low mileage, at the time I think it was at about 88,000 Miles. So they had it for several days and checked into all the electrics and also did a compression check and they said they couldn’t find anything wrong with it and gave me back the vehicle. I’m not really sure why I took it upon myself to do an additional compression test, but this could be helpful to you if your problem was like mine. It was much easier for me to pull the plugs on that suburban. Anyway, I first did the compression test in the same way you did, which was pulling one plug at a time. Again I’m not sure why I decided to try this, but while I was there I went ahead and pulled all the plugs out at the same time and then redid the compression test. What I found was that when the plugs were in I had adequate compression in two adjacent cylinders, but zero compression when the plugs were out In those two adjacent cylinders. I can’t remember for certain I feel like the two cylinders we’re in the middle of the right bank, of course next to each other. The head gasket was blown between the two cylinders that came up on top dead center of compression at the same time. I was getting significant misfires under load, but around town driving I didn’t really notice the issue. If you ever have the plugs out again maybe you’d want to try that? Also I have an LT1 in my 96 Corvette and as soon as I start having trouble with that I plan on securing the service manual for it from Chevrolet. I would hope there would be some good guidance in there as I just sort of expect that my ECM or my opti spark will eventually give me trouble or who knows what else with all those old sensors and connectors :-). It’s been a minute since you posted a video on here Trans Am, have you sold it? Best wishes and happy holiday merry Christmas and happy new year
Pat, thank you for the amount of detail! That is ABSOLUTELY interesting. If my Open/Closed loop doesn't fix the problem, I may very well have to go down that path, though I certainly would not be looking forward to pulling those plugs again! Yes, I still have the car and now that the Stinger is wrapping up (for now), I will likely be back to trying to sort out the Trans Am. Thanks again!!
Been having similair issues with my 94 ta. Scanned it and came up with almost identical codes as yours. Im gunna be changing the pcm in mine soon. Go to oriellys theyll have to order it but its only $130ish. Then youll have to flash it. Best of luck!!! hopefully it helps the both of us.
I bought an innova 5512 to see if it would do the abs bleed procedure, and upon scanning a 94 Z28 got all but 1 of the codes you did. I have no misfire, no service light, and I verified fuel pressure is fine too. I'm not really sure I trust the innova scanner at this point. I think I'll go back to my laptop and scan 9495. Just saw your video and thought I'd share.
Hey biff love the Chanel, but I have A 94 formula with the 5.7 lt1 and I have the same identical codes all 8 what I was wondering is did you find the problem that was causing the problem. Thanks Ron
You know Ron, I don’t think I ever did fully resolve them all, but once I found the problem with the exhaust it has been running good enough that I haven’t gone back and checked!
Check your electrical fuel tank vent solenoid. If the valve is stuck open, for one it would be a constant vacuum leak, but the hitch to that is that at first it would be sucking fuel rich vapor from the tank that would cause an overly rich condition. BUT, after the vapor in the lines and tank are depleted, it would just be a basic vacuum leak causing a lean condition.
Hey biff.. Keith here.. I had the exact same problem with my 96 TA.. however it was nothing to do with the sensors or fuses or fuse blocks.. it was a defect inside the LT1 engine where the piston rod connector sleeve came undone and was literally digging into the cylinder wall of the engine. At the time my 96 TA was under warranty so the Pontiac dealership removed the old LT1 and installed a brand new LT1..
@@keilylmm6377 yeah, now that it’s running I just need to move on to restoration. If you’ve seen any of my truck videos, you know that painting in my current location can be problematic…
@@FearlessMods yes sir... Keep me posted on your restoration on your 94 25th anniversary TA.. I'm still building mine from the ground up in the past 4yrs.. just between life work and family just now enough hrs in the day.....
I'm also in the process of chasing down my misfire issue I just changed my Opti and nothing changed so the next thing I'm going to do is replace my catalytic converters but before I replace them I want to hollow them out and make sure that is the issue
I have the exact car. 94 25th anniversary. 122k miles.. engine was rebuilt and punched out to a 383. Having the exact codes. Bought a new ecm but need it flashed. The tune on this car was written by Ron Zimmer, and would like to keep this tune. How would I go about doing that?
Anthony I have a video in works that I just haven’t been able to complete yet where I use CATS Winflash software with an ALDL cable to download and save the base tune. I would think it should work on yours. In the meantime, this video will step you through it: th-cam.com/video/y3OMK_CLgYo/w-d-xo.html
LOL...Just everything in all the videos! It runs fine cold (Open loop operation) and then stumbles and dies when idling or under acceleration when warm (Closed loop operation)
I have a 98 trans am ls1 , my car battery died after I left on my lights so the next day I tried jumping it off. ...no start , I finally got a code p0601 which is saying PCM problem. I have no control over my injectors or fuel pump and all relays and fuses are good... I'm needing serious help/ advice
Your O2 sensors won't be doing much in open loop mode because the pcm goes off of certain parameters until it warms up. Then in closed loop the O2s come into play and is read by the pcm. If you haven't changed your O2s yet and decide to I would get the Denso O2s because they last longer and work great. I have had a few of the LT1 cars and that's all I would run. Also a tidbit of info about your engine temp and how the pcm works. The temp for the pcm is read off of the water pump sensor not the sensor that is in the driver side head. That sensor is for your instrument gauge only, and if you haven't replaced the sensor in the water pump you might look into doing that as well. I know it seems strange but if that sensor starts to fail it will cause the car to stumble in closed loop. Does your scan tool show any temps or the mv of the O2s?
Interesting and thanks for the comment. I did put bushings in it, but that was in 2008 and before the car vids. Can’t go back and check the footage but I’ll check the service manual.
I wish! Too busy on other projects and this is on the back burner for me. I was looking for an ALDL cable the other day and that'll likely be my next step...to get better diagnosis from the PCM!
@@FearlessMods I am still on your LT1 page. I'm having the same random stutter issue. I didn't know the original owner ( he pasted on, before giving up his knowledge on the car), and was sold on auction to the person I purchased it from. Any further information you or I can give/get, I'm sure, would be interested.
Have you tried looking at the catalytic converters with them being bad or clogged it could cause your car to run rich and also cause a misfire from too much back pressure
@@FearlessMods im having a lt1 tech take a look first to see if its anything else that is causing my issue. Ill keep you updated on it. Ill be having him look this saturday.
,@fearlessmods. Any new updates on the trans am.. been looking for direction before I shoot the parts canon at it. 94 z28 lt1. Idles fine, wide open throttle fine low rpm cruising speed " fish bite " type of miss.
Can i send You my pcm camaro z28 1995 lt1 they have trouble problen can You make work hi perfonce and delete the problem work direc? How much you charge?
Sorry David, I don’t do outside work. More importantly, this PCM is a huge mystery to me and I am not a tuner by any stretch of the imagination! I wish you good luck fixing your issues!
Throttle body gasket usually leaks, messing with the idle control. Even where the pvc hose connects to the throttle body leaks easy. Rear driver side intake manifold gasket has 2 vacuum holes that can easily develop a leak. Rocker valves are prone to sticking. Make sure the valve cover gaskets seat correct. The small stuff... need to be a perfect Autist.
I'm less inclined to think that given what I learned in this video. Open loop (cold) vs. Closed loop (warm) operation... Why would opti work fine in open loop and have a problem in closed loop? Sounds like something else (PCM?) to me...
@@FearlessMods Because that’s what shitty aftermarket Optis do. Ask me how I know. Get yourself a Petris opti or one off Optisparksolutions1 on EBay. That Spectre one you installed is garbage. Installed one of those on mine and it was DOA. Ohm out the coil and have the ICM checked at Autozone. If those check out it’s 100% your Opti.
th-cam.com/video/c3o7RCq94-g/w-d-xo.html That was my car back in the day, 383 with a little laughing gas lol. I have been around the block a time or two with the ol LT1 motor, and my wife now has a 94 Z28 that we did the Torqhead 24x conversion on to do away with any chance of Opti issues.
I would love to give you a hand in setting up you laptop so that you can scan the car for real. My time and the software for free, but you need to get a 4 $ cable from eb ay , let me know if you are interested, i think it would really help you out knowing excatly what the PCM see and the decisions it is making..
@@FearlessMods Great! yeah you need a PC, nothing fancy though! Anything newer than Windows XP that has a USB port is just fine :) I'm not in MO, would have been great though! I'm across the pond in Denmark just outside Copenhagen :)
@@FearlessMods You need the tunerpro *RT* software and the XDF, ADX files for your car. Both software and definitions are free on the tunerpro website. You also need an ALDL cable. I've only ever used the 4$ chinesium cable from ebay but if you dont't want to wait for shipping or just want a professional grade cable you can go with the ALDU1_CABL1 from Moates it is more expensive though!.
I have a 1994 pointiac firebird formula 5.7 litter V-8 automatic I'm not having this issue. But what i did like about your post. Is how your reading up on the information. Available to you. On air. Out loud. On air. I like this. It shows me that your doing your very best to find the problem. And then fixing it. And the fact. That your doing it . Right in front of us. And hands on. So we can understand why you did what your doing.and why your doing. That is such a wonderfull thing. Cause a lkt of people learn by reading. Whyile other leople learn hands on.so to make a long story shorter. I reall like your chanel. ❤❤❤❤
Filimon Gomez, thank you sir! I really like having you as a subscriber!!
Might also want to check your harmonic balancer orientation as I recall they are weighted a certain way from the factory and the crank hub needs to be oriented correctly on the crank snout. Did also find a scenario in which the oil from a cheaper air filter kept coating the MAF sensor causing it to read wrong. Hope these help.
@@roguereductionist8147 thank you for the inputs! If you fast-forward, which I don’t want you to do, lol, it ended up being the catalytic converter!
I have a 95 firebird, and after describing what the battery gauge did my mechanic told me “old cars are just like that”. It behaves exactly like yours does jumping up and down at idle, I’m so glad I found this video.
I’m getting a fire bird and it has electrical problems u think it will b expensive to fix ?
I work at Firestone and found this the other day on Mitchell...
"Technical Service Bulletin
Reference Number(s)02-06-05-004b
Date of Issue: February 14 2006
Service Information
General Motors Engineering, in an effort to determine the root cause of catalytic converter damage, has determined that aftermarket alarm systems incorrectly installed in vehicles have the potential to cause misfires codes and damage to the converter. These alarm systems use a circuit interrupt which utilizes the ignition circuit on the vehicles.
These alarms systems utilize mechanical relays and normal vehicle movement can trigger these relays to engage and disengage the ignition circuit while the vehicle is in motion. These disruptions of the ignition circuit, which occur in milliseconds, may cause more fuel to be commanded. Over time, this dumping of fuel on and off again can cause misfire codes and ultimately damage the converter assembly............."
May be applicable, may not.
Wow! The first thing I did when I bought this thing in 1994 was having aftermarket alarm system installed on it!
Hi Biff, So first kudos on your patience/stubbornness;-) in continuing to pursue this misfire troubleshooting which you have been doing. I know I would’ve run out of patience a long time ago. So I had one experience that gave me a fit a few years ago On a V-8 suburban. I took it to the dealer since I really expected it to be something electrical since it had such low mileage, at the time I think it was at about 88,000 Miles. So they had it for several days and checked into all the electrics and also did a compression check and they said they couldn’t find anything wrong with it and gave me back the vehicle. I’m not really sure why I took it upon myself to do an additional compression test, but this could be helpful to you if your problem was like mine. It was much easier for me to pull the plugs on that suburban. Anyway, I first did the compression test in the same way you did, which was pulling one plug at a time. Again I’m not sure why I decided to try this, but while I was there I went ahead and pulled all the plugs out at the same time and then redid the compression test. What I found was that when the plugs were in I had adequate compression in two adjacent cylinders, but zero compression when the plugs were out In those two adjacent cylinders. I can’t remember for certain I feel like the two cylinders we’re in the middle of the right bank, of course next to each other. The head gasket was blown between the two cylinders that came up on top dead center of compression at the same time. I was getting significant misfires under load, but around town driving I didn’t really notice the issue. If you ever have the plugs out again maybe you’d want to try that? Also I have an LT1 in my 96 Corvette and as soon as I start having trouble with that I plan on securing the service manual for it from Chevrolet. I would hope there would be some good guidance in there as I just sort of expect that my ECM or my opti spark will eventually give me trouble or who knows what else with all those old sensors and connectors :-). It’s been a minute since you posted a video on here Trans Am, have you sold it? Best wishes and happy holiday merry Christmas and happy new year
Pat, thank you for the amount of detail! That is ABSOLUTELY interesting. If my Open/Closed loop doesn't fix the problem, I may very well have to go down that path, though I certainly would not be looking forward to pulling those plugs again! Yes, I still have the car and now that the Stinger is wrapping up (for now), I will likely be back to trying to sort out the Trans Am. Thanks again!!
Been having similair issues with my 94 ta. Scanned it and came up with almost identical codes as yours. Im gunna be changing the pcm in mine soon. Go to oriellys theyll have to order it but its only $130ish. Then youll have to flash it. Best of luck!!! hopefully it helps the both of us.
I bought an innova 5512 to see if it would do the abs bleed procedure, and upon scanning a 94 Z28 got all but 1 of the codes you did. I have no misfire, no service light, and I verified fuel pressure is fine too. I'm not really sure I trust the innova scanner at this point. I think I'll go back to my laptop and scan 9495. Just saw your video and thought I'd share.
Hey biff love the Chanel, but I have A 94 formula with the 5.7 lt1 and I have the same identical codes all 8 what I was wondering is did you find the problem that was causing the problem. Thanks Ron
You know Ron, I don’t think I ever did fully resolve them all, but once I found the problem with the exhaust it has been running good enough that I haven’t gone back and checked!
Check your electrical fuel tank vent solenoid. If the valve is stuck open, for one it would be a constant vacuum leak, but the hitch to that is that at first it would be sucking fuel rich vapor from the tank that would cause an overly rich condition. BUT, after the vapor in the lines and tank are depleted, it would just be a basic vacuum leak causing a lean condition.
Hey biff.. Keith here.. I had the exact same problem with my 96 TA.. however it was nothing to do with the sensors or fuses or fuse blocks.. it was a defect inside the LT1 engine where the piston rod connector sleeve came undone and was literally digging into the cylinder wall of the engine. At the time my 96 TA was under warranty so the Pontiac dealership removed the old LT1 and installed a brand new LT1..
Keith, sorry I’m just seeing this. New LT1 for my ‘94? Yes please!! 😂
@@FearlessMods no problem buddy.. it's been awhile since you posted a video on your 94 TA..
@@keilylmm6377 yeah, now that it’s running I just need to move on to restoration. If you’ve seen any of my truck videos, you know that painting in my current location can be problematic…
@@FearlessMods yes sir... Keep me posted on your restoration on your 94 25th anniversary TA.. I'm still building mine from the ground up in the past 4yrs.. just between life work and family just now enough hrs in the day.....
Hello!! What scanner tool are you using? I’m having the same issue with my 94 Chevy Impala SS LT1
A few. Check out 1994 F-body LT1 Pontiac Firebird Trans Am OBD1 OBD2 code readers
th-cam.com/video/oMFFv9RylOg/w-d-xo.html.
Yay another T/A video!
LOL!
I'm also in the process of chasing down my misfire issue I just changed my Opti and nothing changed so the next thing I'm going to do is replace my catalytic converters but before I replace them I want to hollow them out and make sure that is the issue
I have the exact car. 94 25th anniversary. 122k miles.. engine was rebuilt and punched out to a 383. Having the exact codes. Bought a new ecm but need it flashed. The tune on this car was written by Ron Zimmer, and would like to keep this tune. How would I go about doing that?
Anthony I have a video in works that I just haven’t been able to complete yet where I use CATS Winflash software with an ALDL cable to download and save the base tune. I would think it should work on yours. In the meantime, this video will step you through it: th-cam.com/video/y3OMK_CLgYo/w-d-xo.html
Hey, great video ! What are the symptoms of your misfire ?
LOL...Just everything in all the videos! It runs fine cold (Open loop operation) and then stumbles and dies when idling or under acceleration when warm (Closed loop operation)
I have a 98 trans am ls1 , my car battery died after I left on my lights so the next day I tried jumping it off. ...no start , I finally got a code p0601 which is saying PCM problem. I have no control over my injectors or fuel pump and all relays and fuses are good... I'm needing serious help/ advice
Your O2 sensors won't be doing much in open loop mode because the pcm goes off of certain parameters until it warms up. Then in closed loop the O2s come into play and is read by the pcm. If you haven't changed your O2s yet and decide to I would get the Denso O2s because they last longer and work great. I have had a few of the LT1 cars and that's all I would run. Also a tidbit of info about your engine temp and how the pcm works. The temp for the pcm is read off of the water pump sensor not the sensor that is in the driver side head. That sensor is for your instrument gauge only, and if you haven't replaced the sensor in the water pump you might look into doing that as well. I know it seems strange but if that sensor starts to fail it will cause the car to stumble in closed loop. Does your scan tool show any temps or the mv of the O2s?
Have a 94 firebird 5.7 fuel pump come on but wont stay on any advice getting fuel to the engine but pump wont stay on
Hello friendo, im have a trans am 1994 automatic , and my code obd1 is a 18 what problem is??
Heads up, I'm pretty sure your rear lower control arm was upside down too
Interesting and thanks for the comment. I did put bushings in it, but that was in 2008 and before the car vids. Can’t go back and check the footage but I’ll check the service manual.
Just checked and yup…you’re right! Add to the list of next things I need to do!
I literally have the same codes on my z28 , did you ever find out what it was? Ecu?
Still searching, but getting smarter and closer all the time. Keep watching!
Will do!
Just watched ur newer videos , and going to keep up with them ,subscribed!
Sometimes due to the opti spark cap design you get carbon tracing the traces inside come close to each other and will jump fire to the next cylinder.
did you ever find a sollution to your firing problem?
I wish! Too busy on other projects and this is on the back burner for me. I was looking for an ALDL cable the other day and that'll likely be my next step...to get better diagnosis from the PCM!
@@FearlessMods I am still on your LT1 page. I'm having the same random stutter issue. I didn't know the original owner ( he pasted on, before giving up his knowledge on the car), and was sold on auction to the person I purchased it from.
Any further information you or I can give/get, I'm sure, would be interested.
Have you tried looking at the catalytic converters with them being bad or clogged it could cause your car to run rich and also cause a misfire from too much back pressure
That’s a new one! No, I haven’t even considered that. Everyone automatically defaults to the OPTi. Let me know how your investigation goes!
@@FearlessMods im having a lt1 tech take a look first to see if its anything else that is causing my issue. Ill keep you updated on it. Ill be having him look this saturday.
Biff: Idle is very low= should be 800 RPM !
Hi, for the 93' firebird 3.4 engine L32 - how to check codes?
Guessing you’re gonna need an OBD 1 scanner. Check out my vid th-cam.com/video/oMFFv9RylOg/w-d-xo.html
Had 6 firebird's....My least favorite engine is the LT1....can't beat a 400.
,@fearlessmods. Any new updates on the trans am.. been looking for direction before I shoot the parts canon at it. 94 z28 lt1. Idles fine, wide open throttle fine low rpm cruising speed " fish bite " type of miss.
Not yet. Been very busy with work, but hope to go the PC software route soon. Plus it was damn cold in the garage!
Please tell Me if you figured this issue out yet lol
about to get back at it!
Can i send You my pcm camaro z28 1995 lt1 they have trouble problen can You make work hi perfonce and delete the problem work direc? How much you charge?
Sorry David, I don’t do outside work. More importantly, this PCM is a huge mystery to me and I am not a tuner by any stretch of the imagination! I wish you good luck fixing your issues!
i have a 1994 lt1 motor. can you give me a rear view of the motor? My engine is pouring oil out the back end.
I'd just google it. May be easier to find the specific view you're going for (top rear, bottom rear, uninstalled rear, etc.)
Did you ever figure out what it was
It took a backseat to my newest project. But it’s still on my list!
I have a 95 firebird with the 3.4 and it’s only missing when under a load but no check engine light
22:01 look at your oil pressure... Also more content on this car please!
I'm having the same problem with my 94 cadillac
Vent valve solenoid?
Throttle body gasket usually leaks, messing with the idle control. Even where the pvc hose connects to the throttle body leaks easy. Rear driver side intake manifold gasket has 2 vacuum holes that can easily develop a leak. Rocker valves are prone to sticking. Make sure the valve cover gaskets seat correct. The small stuff... need to be a perfect Autist.
Fuel injector o rings.
Nope. Keep watching!
If your car is still messing up and you havent done it yet try replacing your knock sensor
The mechanic is telling me that is the optispark needs be changed
I'm less inclined to think that given what I learned in this video. Open loop (cold) vs. Closed loop (warm) operation... Why would opti work fine in open loop and have a problem in closed loop? Sounds like something else (PCM?) to me...
Thank you for replying back to me I'm going to change the opti on my car i will let you know what happened thanks again.
@@FearlessMods Because that’s what shitty aftermarket Optis do. Ask me how I know. Get yourself a Petris opti or one off Optisparksolutions1 on EBay. That Spectre one you installed is garbage. Installed one of those on mine and it was DOA. Ohm out the coil and have the ICM checked at Autozone. If those check out it’s 100% your Opti.
Hi. Can I ask you, which diognistic tool you are using? Thanks. Greetings from Spain.
@@franokerman Hello to Spain! For this particular video I was using the Innova 3140. Vid on the readers here: th-cam.com/video/oMFFv9RylOg/w-d-xo.html
th-cam.com/video/c3o7RCq94-g/w-d-xo.html That was my car back in the day, 383 with a little laughing gas lol. I have been around the block a time or two with the ol LT1 motor, and my wife now has a 94 Z28 that we did the Torqhead 24x conversion on to do away with any chance of Opti issues.
I would love to give you a hand in setting up you laptop so that you can scan the car for real.
My time and the software for free, but you need to get a 4 $ cable from eb ay , let me know if you are interested, i think it would really help you out knowing excatly what the PCM see and the decisions it is making..
Daniel I’d love to take you up on that. I’m a Mac guy so let me collect a PC and the cable and let’s do it! You’re not local to St Louis, are you?
@@FearlessMods Great! yeah you need a PC, nothing fancy though! Anything newer than Windows XP that has a USB port is just fine :)
I'm not in MO, would have been great though! I'm across the pond in Denmark just outside Copenhagen :)
@@FearlessMods You need the tunerpro *RT* software and the XDF, ADX files for your car. Both software and definitions are free on the tunerpro website.
You also need an ALDL cable. I've only ever used the 4$ chinesium cable from ebay but if you dont't want to wait for shipping or just want a professional grade cable you can go with the ALDU1_CABL1 from Moates it is more expensive though!.
@@FearlessMods China cable is: Original-6Pin-FTDI-FT232RL-USB-to-TTL-RS232-Serial-Adapter-Cable on ebay
Got the cable and ALDL software finally. Gonna take some first looks tomorrow. First thing I’ll do is look for the software and files from Tunepro.
1994 Pontiac Firebird formula V8 constant Optispark problems replaced it with Petris Enterprises optispark problem solved
Optisparksolutions1 on EBay is another great option. I have one of his and it’s been flawless.