[calvindsy]

Hi, guys,

I have a 1992 Saab 900 Non-turbo hatchback manual, and have been experiencing some problems.

A while back, on a trip to Yellowstone from Denver, I was driving down I-80 (totally normally) when the accelerator pedal stopped doing anything. It felt like it normally did on my foot, but when I pushed it down it didn't do jack with regards to performance. Shifting down into 4th produced the engine braking completely normally but the accelerator stopped doing anything.
I pulled over and attempted to start moving again. I was able to, but with violent misfiring and it was in no way drivable. I then turned the car off, waited about 10 seconds, turned it on and it was completely fine. No missing, no problems--it was my Saab all perfect again.

That was in July. I drove the rest of the way to yellowstone and then back again without any problems -- roughly 750 miles -- and since that time have put around 500 more miles on it.

Last week, on a routine drive in town doing about 40 mph, it happened again. I accelerated after a stoplight and then 500 yards later the accelerator wouldn't do anything. (this is anywhere from slight pressure to completely flooring it--not a change in RPM anywhere). Stopped, tried again without turning the car off, and still misfiring. 'Rebooted' the car and it worked fine.

Two days ago, it happened again and it didn't help to reboot for at least 2 times, so it's getting worse. It happened upon startup this afternoon.

I know little about Saabs and cars in general -- I'm new to the self mechanic world -- but it seems like something in the depths of the EFI computer stuff is dying. It truly is all or nothing -- either it's perfectly normal or like the situation I've described.

Please let me know if you have any ideas.
-Calvin

 

[secondsaab]

Does your check engine light come on? You can do something I never do and read what the codes say from archaic computer control system installed in the C900.

I've had some issues that were similar but not exact.

Classic CPS (Crank Position Sensor) failure, which roughly involves car running for a bit but when engine gets warm car dies. That certainly will give you no gas pedal. It will turn on again after the engine cools, then repeat what I said in first sentence cyclically until I fixed. Had a Saab 9-3 and C900 T16 that did the exact things when bad CPS.

More recent I had a issue that was more closely to yours. Note that there was no CEL (Check Engine Light) present. Car would idle poorly up to the point of near stall at times. Then other times it would idle fine. BUT, it would always do the next thing I describe. Engine would start and stop with no issue, But when I went for a drive it would misfire at higher RPM's. During misfire "gas pedal wouldn't work any more" but the engine would not stall, id back off and continue to cruise along until next time I "laid" on it, misfire. Who knows, maybe could have drove like that for 750 miles like yourself, however at higher demand with the pressing of the gas pedal, it would misfire always.

^It ended up being a bad coil.

 

[calvindsy]

Hi, secondsaab,

Thanks for your reply. (Sorry about my late response, I've been camping out of reception for a bit).

I actually did a bad job replacing a crank seal and damaged my reluctor wheel, which in turn scraped up my CPS. That gave me big misfires and, after replacing both, the misfires disappeared (up until this problem). However, for as long as I've had the car (around April 2015) there's been an intermittent high idle.

The idle has been either present or not from ignition, and has varied in how high it is (2600-3200rpm). When I'm in gear, the car accelerates normally, but feels like it's in cruise control--there's no engine braking. When I slow to a stop, the idle stays high until precisely the moment the car stops moving--reliably. Then it goes down to a normal 800-900ish range. I didn't think this was connected and it didn't occur to me to mention it, but with your problem with the idle it seems like it could be a similar problem.

I'll look at the coil--thanks for the tip. The CPS isn't *new*, it was stolen off another Saab by my mechanic, but it seems odd that it would have failed so quickly. At the same time, I'm confident in my install given the milage that I've put on it since this problem occurred.

Until recently there has been no Check Engine light, but one of the last drives I took it did come on. I did not know you could check a code on a Saab, so I'll check that out as well.

Thanks~
Calvin

 

[secondsaab]

may want to check this out. I dunno much about what you have and have not done. This is good orderly direction for healthy idle.

http://www.saabcentral.com/techhelp/c900/idling_problems.php

 

[16saabs]

I had a CPS go on one of my 900i and it started with intermittent misfire (CEL light came on for a fraction of a second too)but very random, and any speed, anytime, till it failed one day, it had travelled about a mile or so then misfire undriveable, and would wait to cool down then go again till I got home. I replaced it with a s/h unit, and it lasted about 8 months, but the next time it went, it just stopped and that was it, no warning just died and CEL light came on, never to start again. Put another S/H unit on, and it lasted till I sold it, and till after the next owner sold it 3 yrs later, so you can never tell with a s/h unit how long it will last it's S/H and how much wear/use has it had?????