Update: I went to start the car yesterday (about 39 degrees) and it won’t start 🥲 looks like we didn’t end up making much progress in this video (perhaps the title was a bit of foreshadowing with that…) Any suggestions are welcome!
@@MB-qe9wh A bad canister purge valve will cause the engine to be hard to start and run rough at startup after opening and closing the fuel cap. I could imagine that if the seal on the cap would be bad that it would always run rough and be hard to start.
Rough idle is usually dirty injectors, iac, or bad fpr. If there is a small crack in the dist.cap you might get moisture in it when it is colder outside.
The 88 Turbo LH control is pretty primitive and has very little adaptive capabilities. Check for vacuum leaks. Make sure the turbo bypass valve diaphragm is not torn, evaporative vacuum hose and valve, brake booster. Check fuel pressure. You can increase the fuel pressure by moving the top of the fuel pressure regulator where the vacuum hose connects with a socket and hammer. Also I have had bad MAF sensors create a hard start and idle surge when cold. Ignition wise make sure the plugs are gapped correctly and are good quality NGK in the correct heat range. Check for strong spark on cold crank.
The electronics in this fuel system ECU is old tech and programming. There's nothing wrong with that, it just takes a *long* time for it to settle in. Different than what we're used to with newer models. Great job Jacob.
The 'swinging' RPM:s during cold start might be the Jetronic fuel system attempting to adapt the fuel injection to the fuel. Shouldn't normally be an issue once the adaptation has set. This used to be an 'issue' when I was converting my and a friend's 900 to run on E85 - each time we disconnected the battery, the Jetronic system lost its adapted values for fuel trim, resulting in the car being hard to start when cold before the system had fully re-adapted to E85 fuel wise. You might get similar issues if the fuel/air mixture is not at all what the ECU expects. I'd also check the functionality of the O2 sensor to make sure that the Jetronic can do its job with respect to long-term fuel trim.
Yes. The one-lead connector on the O2 is the DC voltage signal from the sensor. The two-lead connector is the pre-heater -- this is not going to affect running. As shown in the service manual page 240-16 at warmed up idle this value should oscillate between 0.4 and 1 VDC. Make sure this connector is unplugged, this voltage will come right from the O2 sensor (when measured against chassis ground). On my 1993 900 I can connect the Tech2 to the ECU (under the rear seat) and graph the O2 sensor to see the oscillating value.
Did you check that the regulator valve in the iac rotates freely? I had trouble with cold start and it turned out that valve was stuck because of a jagged edge. Don't ask me how that happened but they are of aluminium. I took the iac from the donor car and the problem was gone. You can check the valve by giving it 12 volts.
It may be harder to check with that 90 degrees angle; on a 9000 it is straight through which makes it easier. The valve is closed when it is not in operation. The regulator is round. Hopefully the outside is visible from the connection on the side. If so, when you take a small flathead and press it gently to the valve you should be able to move it. It shouldn't take much force to move the valve. Another way to test is to put 12 volts on the terminals, that should turn the valve wide open.
IAC valve can be disassembled (at least on lucas injection models), only by spraying carb cleaner on the openings probably won't clean it deeply. Also check for vacuum leaks, distributor ignition advance and the pcv hose under the intake manifold that connects the turbo suction pipe to the valve cover
I have pretty much the same idle issues with mine too (LPT)! But it does not completely disappear when the engine is warm - the idling behaviour sounds pretty much identical.
Unfortunately the Classic 900's were not equiped with the same ECU /ignition system. So no DI to swap out. But on the 9-3/9-5 OG they where a failure point, and if so replace with OEM if possible Also, I just LOVE the sound of a classic 900T Makes me miss mine
I have the same issue with the surging idle when cold. It goes away after driving but then I have a high idle like 1500 rpm. My idle screw bolt is adjusted all the way out. 88 SPG. What I'm hoping you can do is a video on the surging issue as so many of us are having the same issues
Very interested to see if you can resolve the hunting idle issue. I’ve been chasing the exact same issue on my ‘88 SPG for the past 8 years. Early on, I had two separate SAAB certified mechanics look into it and both gave up. Basically told me these engines often had this issue even when new. In the meantime, I’ve replaced so many things to no avail; AIC, MAF, FPR, O2, coolant sensor, vacuum lines, distributor cap & rotor, plugs & wires, and the list goes on. I haven’t touched my fuel injectors yet, but I’m heading in that direction, next. Also, my issue is definitely worse in the winter than in the heat of the summer (I live in Iowa).
@@AutoAutopsyGOOD NEWS!!! I fixed it!!! A few days ago I was fiddling under the hood and I decided to take the MAF sensor off and clean it. As I recall, this is the 2nd or 3rd one I’ve installed. I had some defective units that were rebuilds. When I put it back on I forgot to plug it back in. Went to started the engine and the CEL came on, it immediately reminded me that I had left it unplugged. Instead of turning it off, I let it run. To my surprise, it didn’t start the usual surging that its done for the past 8 years. It was running a bit rough, but it wasn’t surging. So, i decided to buy another MAF and see what happens. New (rebuilt) Bosch unit shows up a few days later. I adjust the ohms to factory spec, install it, and Viola! She starts right up, holds the idle around 1100-1200 for a minute or two then slowly idles down to 900. Doesn’t surge or stall and runs really smooth. I’ve been driving it for a few days now and it’s running better than ever! Sooo, I would highly recommend you start by checking the ohm setting on your current MAF and see if it’s set correctly. Bentley manual shows how to adjust it or I can send you details. This may fix your issue. Or, you might want to get another unit.
I had idle problems check for leaks. Be nice to the idle valve i use WD-40 i used aceton on one and it was NOT happy, stalled the car on the road, not fun. I got some "bug" in my ECU. the idle just disappears some times only happened twice. "reboot" it by taking of the battery pole for a couple of minutes.
sorry, I am having a bit of trouble understanding what you are suggesting! are you saying to check for vacuum leaks and disconnecting the battery to reset the ecu?
@@AutoAutopsy yes vacuum leaks and "reboot" ECU by making the car powerless for a couple of minutes. Saw now that it does not start anymore. Does it got spark, you got a spare spark coil to try? Fuel pressure, is it ok? Does the fuel pump even run? Check the fuses, they can start to go when for example the fuel pump starts to go bad.
Yeah. That's so annoying. Rough idle. My guess is a fuel pressure problem. You need more pressure when the engine is cold. You start with the injectors. To test them use a large syringe with a piece of hose that fits over the end of the injector fuel nipple. Then apply pressure to the injector ( removed) with the syringe filled with water. Then apply 12 Volts to the injector and see if the spray patten is good an even across all 4 injectors. You can soak your injectors in a fuel system cleaner additive over night. Pour some into a shallow tray and place the injectors so the terminals are face up and clear of the fluid and dry. You could put the cleaner directly into the tank but this is much slower. If all is good then the fuel pressure regulator may be suspect. If ok then the filter maybe clogged with dirt. It maybe just be old and need replacing. Then last, and I hope not, the fuel pump. Can be costly. Cheers from downunder.
@@AutoAutopsy I looked it up some apparently did long shot but it's worth a check, I know My 98 Jeep had one and when it got cold wouldn't start frustrated thinking I have a Jeep its 4wd and I can't even start it then by chance I saw the round button and wires on the battery try bottom read what it did didn't even check it just replaced it, your may not work but it's worth looking at
Update: I went to start the car yesterday (about 39 degrees) and it won’t start 🥲 looks like we didn’t end up making much progress in this video (perhaps the title was a bit of foreshadowing with that…) Any suggestions are welcome!
Does the idle change anything if you open the gas tank? Does your gas tank cap have a good tight seal?
@@dankuspanku4650I also have a rough idle when cold in my 88 SPG. How would opening the gas cap potentially affect the idle?
@@MB-qe9wh A bad canister purge valve will cause the engine to be hard to start and run rough at startup after opening and closing the fuel cap. I could imagine that if the seal on the cap would be bad that it would always run rough and be hard to start.
I didn't have time to watch the video entirely, and maybe you have already checked it, but could it be crankshaft position sensor?
have you considered converting to trionic 5 to get better diagnostics?
Rough idle is usually dirty injectors, iac, or bad fpr. If there is a small crack in the dist.cap you might get moisture in it when it is colder outside.
thanks for those suggestions, Tom!
The 88 Turbo LH control is pretty primitive and has very little adaptive capabilities. Check for vacuum leaks. Make sure the turbo bypass valve diaphragm is not torn, evaporative vacuum hose and valve, brake booster. Check fuel pressure. You can increase the fuel pressure by moving the top of the fuel pressure regulator where the vacuum hose connects with a socket and hammer. Also I have had bad MAF sensors create a hard start and idle surge when cold. Ignition wise make sure the plugs are gapped correctly and are good quality NGK in the correct heat range. Check for strong spark on cold crank.
thanks for those suggestions! really appreciated
The electronics in this fuel system ECU is old tech and programming. There's nothing wrong with that, it just takes a *long* time for it to settle in. Different than what we're used to with newer models. Great job Jacob.
thanks!
It's a cool car and worth the effort
it sure is!
The 'swinging' RPM:s during cold start might be the Jetronic fuel system attempting to adapt the fuel injection to the fuel. Shouldn't normally be an issue once the adaptation has set. This used to be an 'issue' when I was converting my and a friend's 900 to run on E85 - each time we disconnected the battery, the Jetronic system lost its adapted values for fuel trim, resulting in the car being hard to start when cold before the system had fully re-adapted to E85 fuel wise. You might get similar issues if the fuel/air mixture is not at all what the ECU expects. I'd also check the functionality of the O2 sensor to make sure that the Jetronic can do its job with respect to long-term fuel trim.
Yes. The one-lead connector on the O2 is the DC voltage signal from the sensor. The two-lead connector is the pre-heater -- this is not going to affect running. As shown in the service manual page 240-16 at warmed up idle this value should oscillate between 0.4 and 1 VDC. Make sure this connector is unplugged, this voltage will come right from the O2 sensor (when measured against chassis ground). On my 1993 900 I can connect the Tech2 to the ECU (under the rear seat) and graph the O2 sensor to see the oscillating value.
thanks you both!
The joys of classic car ownership. Hope you figure out the starting issue.
:') I do too! thanks lol
Did you check that the regulator valve in the iac rotates freely? I had trouble with cold start and it turned out that valve was stuck because of a jagged edge. Don't ask me how that happened but they are of aluminium. I took the iac from the donor car and the problem was gone. You can check the valve by giving it 12 volts.
I'm not sure how to verify if it's moving freely; do you have any info on how to check that?
It may be harder to check with that 90 degrees angle; on a 9000 it is straight through which makes it easier. The valve is closed when it is not in operation. The regulator is round. Hopefully the outside is visible from the connection on the side. If so, when you take a small flathead and press it gently to the valve you should be able to move it. It shouldn't take much force to move the valve. Another way to test is to put 12 volts on the terminals, that should turn the valve wide open.
IAC valve can be disassembled (at least on lucas injection models), only by spraying carb cleaner on the openings probably won't clean it deeply. Also check for vacuum leaks, distributor ignition advance and the pcv hose under the intake manifold that connects the turbo suction pipe to the valve cover
how can you dissemble it? I asked some 900 folks and they didn't have any pointers on dissembling it further/at all
@@AutoAutopsy i am pretty sure you got bosch system, lucas valves you can disassemble, bosch i sadly do not know about.
I have pretty much the same idle issues with mine too (LPT)! But it does not completely disappear when the engine is warm - the idling behaviour sounds pretty much identical.
bummer - hope you get it solved
Looks great!
thanks!
Hey, my 1999 93 Se had the same issue, my mechanic replaced the ignition Cassette ( that red thing ) and that seemed to work. its kind of expensive
Unfortunately the Classic 900's were not equiped with the same ECU /ignition system. So no DI to swap out. But on the 9-3/9-5 OG they where a failure point, and if so replace with OEM if possible
Also, I just LOVE the sound of a classic 900T Makes me miss mine
thanks for the suggestion! but unfortunately completely different car :(
I have almost the same car, and in the now-22 yrs I've had it, it's had 4-5 DICs. So many, the part almost seems less-expensive and NBD now.😂
I have the same issue with the surging idle when cold. It goes away after driving but then I have a high idle like 1500 rpm. My idle screw bolt is adjusted all the way out. 88 SPG.
What I'm hoping you can do is a video on the surging issue as so many of us are having the same issues
it sucks :( your throttle cable might need adjustment if your idle is high. I previously had that issue on mine
@AutoAutopsy thank you I will check that next.
Very interested to see if you can resolve the hunting idle issue. I’ve been chasing the exact same issue on my ‘88 SPG for the past 8 years.
Early on, I had two separate SAAB certified mechanics look into it and both gave up. Basically told me these engines often had this issue even when new.
In the meantime, I’ve replaced so many things to no avail; AIC, MAF, FPR, O2, coolant sensor, vacuum lines, distributor cap & rotor, plugs & wires, and the list goes on. I haven’t touched my fuel injectors yet, but I’m heading in that direction, next. Also, my issue is definitely worse in the winter than in the heat of the summer (I live in Iowa).
ugh!! sorry to hear. that's annoying. I am now less confident in solving that lol
@ Don’t let my failures discourage you. I’m still optimistic that one of us will figure this out. Keep going!!!
@@saabstory2 have you checked for air leakage at the intake manifold where the intake mounts to the block?
@ I have not. Guess I’ll be doing that next.
@@AutoAutopsyGOOD NEWS!!!
I fixed it!!!
A few days ago I was fiddling under the hood and I decided to take the MAF sensor off and clean it. As I recall, this is the 2nd or 3rd one I’ve installed. I had some defective units that were rebuilds. When I put it back on I forgot to plug it back in. Went to started the engine and the CEL came on, it immediately reminded me that I had left it unplugged. Instead of turning it off, I let it run. To my surprise, it didn’t start the usual surging that its done for the past 8 years. It was running a bit rough, but it wasn’t surging. So, i decided to buy another MAF and see what happens. New (rebuilt) Bosch unit shows up a few days later. I adjust the ohms to factory spec, install it, and Viola! She starts right up, holds the idle around 1100-1200 for a minute or two then slowly idles down to 900. Doesn’t surge or stall and runs really smooth. I’ve been driving it for a few days now and it’s running better than ever!
Sooo, I would highly recommend you start by checking the ohm setting on your current MAF and see if it’s set correctly. Bentley manual shows how to adjust it or I can send you details. This may fix your issue. Or, you might want to get another unit.
I had idle problems check for leaks. Be nice to the idle valve i use WD-40 i used aceton on one and it was NOT happy, stalled the car on the road, not fun. I got some "bug" in my ECU. the idle just disappears some times only happened twice. "reboot" it by taking of the battery pole for a couple of minutes.
sorry, I am having a bit of trouble understanding what you are suggesting! are you saying to check for vacuum leaks and disconnecting the battery to reset the ecu?
@@AutoAutopsy yes vacuum leaks and "reboot" ECU by making the car powerless for a couple of minutes. Saw now that it does not start anymore.
Does it got spark, you got a spare spark coil to try?
Fuel pressure, is it ok? Does the fuel pump even run?
Check the fuses, they can start to go when for example the fuel pump starts to go bad.
Yeah. That's so annoying. Rough idle. My guess is a fuel pressure problem. You need more pressure when the engine is cold. You start with the injectors. To test them use a large syringe with a piece of hose that fits over the end of the injector fuel nipple. Then apply pressure to the injector ( removed) with the syringe filled with water. Then apply 12 Volts to the injector and see if the spray patten is good an even across all 4 injectors. You can soak your injectors in a fuel system cleaner additive over night. Pour some into a shallow tray and place the injectors so the terminals are face up and clear of the fluid and dry. You could put the cleaner directly into the tank but this is much slower. If all is good then the fuel pressure regulator may be suspect. If ok then the filter maybe clogged with dirt. It maybe just be old and need replacing. Then last, and I hope not, the fuel pump. Can be costly. Cheers from downunder.
thanks for the tip Chris!!! I figure if it's a fuel injector issue, would it not have the issue all of the time, not just when it's cold?
What was the actual size of the gap that you filled with the tape? That is, what would have been the right size?
what gap? and what tape are you referring to? Are you asking about the bumper trim?
Is it possible to get some data from the ECU to help diagnose the problem?
I don't think so given how old the car is :( thanks for the idea
Is the paint damaged on this car on several places?
Yup. Arizona sun.
yes. it will need a respray eventually. I bought it like that
did Saab ever put a battery temp sensor in their vehicles
not that I am aware of
@@AutoAutopsy I looked it up some apparently did long shot but it's worth a check, I know My 98 Jeep had one and when it got cold wouldn't start frustrated thinking I have a Jeep its 4wd and I can't even start it then by chance I saw the round button and wires on the battery try bottom read what it did didn't even check it just replaced it, your may not work but it's worth looking at
Its the little things... 👏👍🙂🇸🇪
:')
Any plans to do a paintjob on this car?
100% once I have a place to store it inside and everything else is fixed. It likely won’t be a good bit of time
🫡👍❤️🇸🇪
:')