poor starts when warm

[deniss]

It's kind of a strange problem. When I start the car and the engine is completely cold, it starts perfectly fine and behaves well. But if I start the engine that's warm or hot, it settles to a low and unstable idle... It would idle at around 700 or even dip to 500 and recover... Doesn't seem to matter how the idle screw is adjusted on the throttle body. When I go to drive her a bit, she idles perfect after that... But something about starting her warm or hot that she doesn't quite like...

Any suggestions on where to look? It is likely one of the ignition components again or ignition wires not seated deep enough into the coil or something? I do get occasional misfires, but they are always more likely when the car is cold.

[ProfZ]

First thing I'd check is the throttle body switch.

With engine off, open the throttle about 1/4 by hand. Slowly return it to closed. Do you hear the switch click when throttle is "home" to idle position? If not, try adjusting it so it does (there are postings on this).

Also, look to the AIC valve: Flush it out well with WD-40 or carb cleaner, and see if this helps. Check its resistance following the Bentley manual's instructions.

Basically, if your engine idles without misfiring when the low-idle problems happen, you can ignore ignition issues for now--they're a separate problem. Of course, if misfire causes the low idle, the ignition system is the first thing to investigate

[deniss]

Both the TPS and the AIC are just fine, and I cleaned AIC, throttle body, and adjusted TPS just recently, so those are all in good order.

I think there must be a misfire of some sort there. Because once I let it idle after just turning the ignition on, and a misfire nearly knocked it out, but the car was able to recover and resume idle. Then when you step on the gas for the first time to start driving, it chokes a bit first, and then it's fine... After a little driving - things are perfectly normal. Hm.

If the weather wasn't so bad I'd put dielectric grease on my ignition wires' king lead (at the coil) and see if that helps. It's been very wet out here for the last week or more, and this problem started getting more pronounced during this very wet season.

[deniss]

Well, I put some dielectric grease on the ignition wire leads at the coil and the distributor. I haven't done it at my plugs. Maybe I should do that as well. It seemed to have helped the misfiring while I drive, but it didn't help my low idle... I've adjusted lots of things by now - I'll the obvious things I've read about on here:

Adjusted idle screw
Measured voltage and resistance on AIC - up to specs
Tested the TPS for continuity at idle - fine, although it takes a second or two to establish continuity after returning from open.
Wiggled ignition wires and vacuum lines while idling - no change in idle

What else to try?

[REDTURBO84]

Originally Posted by deniss

It is likely one of the ignition components again or ignition wires not seated deep enough into the coil or something? I do get occasional misfires, but they are always more likely when the car is cold.

The missfiring problem must be addresed first . I would use some injector cleaner in a full tank and get the correct ngk plugs .Test the resistances on the plug and coil wires as per bentley.Pat

[deniss]

Injectors were cleaned just a couple months ago. I put in a brand new set of NGK plugs a couple months ago and gapped each one as per spec.

I think it might be getting fed too much fuel when the car is started. Can that kill the idle down to 700 if it's flooding and running too rich? I checked NTC sensor and O2 sensor to be working correctly at operating temp, but maybe my O2 sensor doesn't immediately come on when I turn the car on and it's warm...

Can these be possibilities to consider?

[deniss]

Ok so the dielectric grease improved matters a LITTLE, but the idle quality isn't the best because she's shaking a little and a popping a bit, as though the timing is off or if it's misfiring. Other times she'd be idling fine. No pinking when I drive. Gotta be electrical... These intermittent things are hard to trace.

[Vermont Saab]

I assume you are working on your 87 SPG, sometimes the cause of a misfire or poor running in a turbo can be traced to the wiring leading up to the hall effect sensor on the dist. You might want to check the quality of the connection of the hall effect sensor of the distributor. The wiring/connection is a common place of grief for those cars, try GENTLY wiggling the wire, and it's connection with the car running and see if any change happens. Oftentimes I cut and splice a pigtail of a newer car, and change the dist. to the updated style, they seem to have a much better connection. IIRC you can still buy a "rebuild" kit for the dists. off of the older cars.

[deniss]

I actually did rebuild my distributor with that rebuild kit in October... But the pigtail plug for the Hall effect sensor is original from the car's harness, so it's pretty crusty. It could be it... I might put some dielectric grease on that plug. Maybe just my distributor is old and needs to be replaced!

[deniss]

Ok, it seems that my ignition wire lead on spark plug 1 was loose. I just pulled very gently on it and it proceeded to slide right off. So I did my best to seat it firmly and deeply, and it seems that it is now. But I wonder why it would come off at all! Should I compress the connector ring on the ignition wire lead so that it sits more snuggly against the spark plug??

[deniss]

Well that didn't do it. The car must be cursed with the demon of bucking and misfiring... Why is it such a problem?!? Why can't I just be able to actually *enjoy* driving my car without having to solve one electrical problem or the other! I think I might try getting rid of my Magnecors and putting my old Boughicords back in and see if it makes any difference. It's a quest for a misfire-free ride that I just can't seem to win....

[Vermont Saab]

Maybe a new set of wires is in order.

[deniss]

Yea, I think I'll buy a set of brand new Boughicords next.... But the trouble is, currently I am using a set of Magnecor ignition wires I bought in October 2004 - so they are pretty much brand new! These wires are supposed to last, but maybe they are arcing like Matthew warned. I'll just have to change them out and see.

[Vermont Saab]

If you can the way to go is to get the Bougicord wires, I have also had pretty good luck with STI wires. Say, where in Jersey are you from?

[deniss]

Princeton vicinity in NJ (central)