Carrera won't idle in cold weather

[IlMostro]

Now that it is getting colder here I'm having a problem keeping my car (86 Targa) running when I stop.

Although I do have a bit of an stumble all the time (a gentle foot while pulling away seems to take care of it), the problem I'm having now is that when I stop. It's noticable when temps get below 50-60F. When I stop, no foot on the gas, the engine will idle normally for a period, then the revs dip. Sometimes the engine will keep running, sometime it'll die. The colder it is, it seems like it has a greater tendency to die. If it's not too cold out, say 50F, when the engine is warm it idles ok. But if its in the 30s I need to heel/toe to keep the revs up.

Idle sensor seems to be working ok, I can hear it click off/on when moving the throttle.

When it's warm out, or during normal driving everything is pretty good. Sometimes I do get a "hiccup", again more pronounced when the engine or air is cold if I don't ease on the throttle.

I have done A LOT of searches to try and figure this out. Unfortunately there are a lot of others who have had various "cold idle" problems that come up in my searches, the results I get are dozens of pages long.

Best Regards,
Daryl
Milw, WI

[kqw]

Here's something you can do fairly quickly:

Check the torque on you manifold bolts, all 12 of them (18ft/lbs)

[scottb]

Take it to your wrench and have him adjust the mixture.

[nhromyak]

Originally posted by scottb
Take it to your wrench and have him adjust the mixture.

I second that.

IIRC - the mixture will need to be checked cold. As when the O2 heats up, it leans (or richens) the mixture and the car (probably) idles good.

Intake manifold gaskets, DME relay, Head Temp sensor was it updated?...

Grounds on the manifold intake #1 runner.

Good luck.

[IlMostro]

Thanks guys, will check manifold bolts, relay sensor, etc and take it in for the mixture check.

Regards,
Daryl

Milw, WI

[scottb]

Even if it tests good now, you should replace the DME relay if it hasn't been replaced in awhile. It's inevitable that it will go bad. You might consider buying two...one to install now, and other other to leave in the glove box for emergencies. Our host sells them.

Let us know how your troubleshooting goes.

Scott

[jbrinkley]

this is what I did after reading all the carrera idle issues from th epast, I just made a big list and went to town

remove air box, mass air, throttle boot, ICV valve
remove and label all vac lines, oil tank line with inside restrictor on tank valve. CC servo lines, a couple from the back of the throttle boot, also the pipeline (copper tube)

Test all sensors recommended in bentley guide, replace anything that fails.

replace DME, distributor cap and rotor, plugs, fuel filter, air filter.

put it all back and adjust idle like in previous threads with bypass wire in plug.
My idle problem was fixed after all this, hot or cold.
one comment about idle setting, it took more than a couple days to get it right, where it wouldn't bounce when cold. There's a perfect spot and it took me a while to find. now it starts up and idles perfectly everytime, I'm not buying a gas analyzer.
There are cheaper and better ways to do this but I wanted it done more or less in a day, with no computer time in the middle to ask questions or do more searches.

I would be lost without pelican and that bentley book

[stlrj]

If too rich at idle, my 86 would stumble and tend to stall when taking off when cold.

Leaning usually takes care of it.

I hope your problem is as easy to fix.

Cheers,

Joe

[IlMostro]

Update

ICV valve is ok
Replaced ref and speed sensor
Replaced DME relay
Manifold bolts are ok
Vac lines ok
Mixture is ok

I was incorrect about when the problem happens. Although it is more likely for the engine to die when the engine is cold and/or it is cold outside, it still will dip when the engine is warm, even when in a heated garage.

It seems to be spark related. With a timing light hooked up, it's as though the spark cuts out when it stumbles/dips.

I have a Steve W chip on the way, and had hoped to have everything working right before installing. From what I've read the chip could fix the problem though too.

Will update if/when there's more to report.

Open to suggestions!

Regards,
Daryl

[geof33]

Check all of your grounds. Check your wiring to the coil... replace your coil. Make sure your coil wire is fully seated... What wires are you using? Sometimes the wire feels like it all the way in, but it's not...