PeteL

As you all know, my car is running horribly when cold. It idles extremely rough (although at the correct RPM). As cold as it has been lately, it sounds awful and is down on power most of the way to/from work (35 miles). Sounds like a Harley Davidson.
It will occasionally "pop" and idle smooth and the power returns.
When it is warmer, it pops and smoothes out after running for a few minutes.
Could my ISV be sticking?
Thanks
Pete

Luis de Prat

If it goes away eventually as the car warms up, I'd say yes.

If not, your AFM may be malfunctioning.

Red1

I'll second that.

PeteL

It goes away once car and the air entering the car is warm. When it is really cold outside it doesn't.
Although last night, I stopped on the way home. When I re-started the car, it was smooth. I am leaning towards, the ISV.

Red1

Mine was running very poorly when cold. It would nearly stall when shifting while still cold, but ran pretty well once warmed up. New ISV, and that took care of it.

pikey7

Could be the ISV, but I doubt it. If it was the ISV you would have a very low idle when cold aswell as the bad running issues. I'd be more inclined to suspect it's the thermoswitch in the head sending the wrong signals to the DME.

But, the free and relatively easy fix is the ISV, so give it a swill out with carb cleaner first.

Techno Duck

You might want to check the blue topped sensor with a connector that is similar to the fuel injector harness. Its located at the front, top of the block under throttle body. The sensor sends a signal based on watertemperature to the DME. I have a feeling this sensor is related to my problems with a rough idle on WARM startups. I am also changing the ISV for good measure. Also note, to change the ISV, you will need to take the intake manifold off.

The part # for this sensor is...

944-606-125-00

cas951

Could the ISV effect my idle not able to adjust? No matter how many turns on the idle screw my idle doesn't change. Even if I follow clarks garage procedures. The car runs great. Maybe for a few seconds after it starts when cold it sort of runs rough for about 3 seconds but idles fine after that.

H2Opumpr

Pete-

I feel your pain, but your problem seems like it's getting worse compared to previous posts.

I won't suggest all the normal changes, as they have been suggested before. "search function"

Are your grounds good? I mean really good.. My similar problems have been getting better with many ground fixes. One thing that helped me was getting the DME resoldered. Poor grounding caused heat build up in the DME and eventually small cracks appeared in the joints. Fixing this has cleared many drivability problems related to cold. Cold is a relative term of course.
Cars still like to operate at a given temp and the DME may work best at 80 and above temp if it is comprimised. Remember the DME is in the footwell,... if you park your car outside in the sun on a colder day does it run better? Mine did... also the cruise control operates correctly when the heat is on during a cold day. The CC brain is in the drivers footwell.... and those solder joints expand.

May seem like a stretch but I believe most of us have some similar problems and this cold drivability issue is for real....and the regular checks and replacements have seem to run out. Just food for thought.

Add grounds. I was lucky to pick up one of Icesharks (Dan) kits just when he passed, and it helped tremendously ...and has fixed problems that seems like it shouldnt have. Maybe its a stretch but check all that stuff.

Shawn

PeteL

I will go through the grounds. I really think this is an air issue. Perhaps even a headgasket, although I don't have any other symptoms. I am pulling the intake this weekend to take a look at the ISV. Will clean it up and put it back together. If it runs better, fine. If not, I am going to look at the HG. I want to clean/paint the Intake and the cam cover anyway, this just gives me an excuse. Luckily, I have another car, so I can take my time. Just no fun driving a Porsche that sounds like a Harley.