[Siggy]

1989, 16V 900, with automatic transmission; 83,000 Miles

The behavior: Pulsey, rough, but even, idle especially when placed in reverse. In reverse the idle causes vibration. In forward gear, doesn't shift to third at the appropriate speed -- seems to delay shifting up.

I changed the transmission fluid and filter (Type F was used and I changed it twice (second time after a test drive) to get as much of the fluid in the converter out.

I found 4 vacumm leaks and fixed those.

I'd appreciate any ideas as to what would cause these symptoms.

Siggy

 

[Zelandeth]

As for the vibration, not sure, possibly an ignition problem, or just the idle speed being too low (that's why mine seems to rough at idle, it's idling at about 400rpm in gear - I set the idle speed when there were a bunch of vacuum leaks). Increasing idle to ~800rpm stops any shake. You might want to check plugs and such though, make sure you don't have a misfire or anything like that causing problem at tickover.

Could also be a dodgy engine mount I guess.

As for the delay in shifting to 3rd gear, I have that too - in my case I'm sure it's a problem with the adjustment of the kick-down cable, as it worked just fine before I fiddled with the plate the throttle and kickdown cables attatch to (one of the bolts holding it on had fallen out of mine), and lifting off the throttle slightly will make it kick into third fine. Could also be a problem with the front brake band adjustment. I'm going to investigate this once the car's road legal again. MOT, hence handbrake and CV boot have priority I'm afraid though!

 

[Siggy]

As for the vibration, not sure, possibly an ignition problem, or just the idle speed being too low (that's why mine seems to rough at idle, it's idling at about 400rpm in gear - I set the idle speed when there were a bunch of vacuum leaks). Increasing idle to ~800rpm stops any shake. You might want to check plugs and such though, make sure you don't have a misfire or anything like that causing problem at tickover.

Could also be a dodgy engine mount I guess.

As for the delay in shifting to 3rd gear, I have that too - in my case I'm sure it's a problem with the adjustment of the kick-down cable, as it worked just fine before I fiddled with the plate the throttle and kickdown cables attatch to (one of the bolts holding it on had fallen out of mine), and lifting off the throttle slightly will make it kick into third fine. Could also be a problem with the front brake band adjustment. I'm going to investigate this once the car's road legal again. MOT, hence handbrake and CV boot have priority I'm afraid though!

This problem is perplexing because I changed the spark plugs and rotor and the car was running fine. The idle is at 800, and there was no change in the kickdown adjustment before the problem occured (literally right after the transmission oil change). The motor mounts are good also. I thought that I got the transmission oil level wrong and that that caused the problem. The oil level appears to be perfect -- just above the cold-engine maximum mark after driving the car for 5 minutes.

Siggy

 

[Zelandeth]

Hmm, okay then, I don't know what to suggest! Only thought would be that your AT has decided that now is the time to be awkward, whether caused by the oil change or not I don't know.

Good luck with getting it sorted!

 

[Siggy]

Thanks for the reply anyway -- it's a tough problem. I'm going to try draining some transmission fluid.

Siggy

 

[ProfZ]

Had the same idle problem in our 1990 900 auto. When you load the engine by shifting trans into D or R, the AIC valve is not responding immediately to the ECU's call for more air to raise idle--which sets up an oscillation.

Most likely, you just need to remove the AIC and flush it with WD-40. If this doesn't help, or helps only temporarily, try another AIC.

As for the delayed upshift--is this a delay into second or third? It's easy to confuse the two.

 

[Siggy]

Had the same idle problem in our 1990 900 auto. When you load the engine by shifting trans into D or R, the AIC valve is not responding immediately to the ECU's call for more air to raise idle--which sets up an oscillation.

Most likely, you just need to remove the AIC and flush it with WD-40. If this doesn't help, or helps only temporarily, try another AIC.

As for the delayed upshift--is this a delay into second or third? It's easy to confuse the two.

Thanks so much! And, the shift delay is from 2nd to 3rd. It seems to just hand there in the 3000 RPM range just a few seconds too long.

Siggy

 

[Zelandeth]

Hmm, that's an idea I guess. The Oscillation-type symptom. The same sort of thing could be caused by the flow meter in the CIS system not responding as quickly as it should, couldn't it? Not in any way trying to hijack the thread, just that I do have a similar symptom, albeit not very pronounced and I never thought of that as a cause. Still feeling my way around this injection system, it's a clever one though, that's for sure.