m20 idle issue:) again

[2002jm]

Last Fall I noticed my e21 with a m20 engine would start and then not idle until it was warmed up; temp needle over 1/4. I thought I had it fixed when I replaced the temp sensor.
Went out today and started the car after a long cold winter. Car started right up but will not idle at all until it is warmed up. Once it warms up; perfect 850rpm idle.
So I am thinking there is a vac. leak. Could the icv leak at the front of the throttle intake and cause this problem? It did seem a bit lose. I tried some carb cleaner, but idle did not change.
However, when I moved the icv around the idle changed. So I am thinking vac. leak at the boot intake, or somewhere related to the icv.
Also, the brake booster connection to the front of the throttle does not seem all that tight...
Any ideas???
Car runs so good when it is warm.....and not at all when cold:(
thanks for any help,
jm

[tomstin]

will not idle at all until it is warmed up.

Explain that statement a bit more. Idles fast? Have to keep your foot on the pedal?

ICV leaks will be a problem but I would guess if it was leaking you wouldn't get the idle you have once warm. But these engines are notoriously sensitive to vacuum leaks.

[2002jm]

thanks for the reply

When it is maybe 50 degrees outside, I start the car and it just runs for maybe 5-10 seconds and slowly dies. If I put my hand on the throttle and hold it open it will stay running but as soon as I let go it dies. Once it warms up, it runs fine, 850 rpm pretty smooth; not prefect of course:).
I did change the temp sensor; the blue one. of course I could have been sent a bad one???
I do know the coolant pipe was sucking air, but not sure that would make any difference. I sprayed carb cleaner on the hose and I could see it bubbling and pulling the cleaner in.
thanks for any input.
john

[tomstin]

I do know the coolant pipe was sucking air, but not sure that would make any difference. I sprayed carb cleaner on the hose and I could see it bubbling and pulling the cleaner in john

Fix that first, again, these engines are notoriously sensitive to vacuum leaks.

[2002jm]

idle still bad

So the car has been in storage and now I went out to start it and it will not idle at all unless it is warm. Once the temp needle moves to the middle it idles but has a 500 rpm surge. If the car is cold it will not idle at all. Took the icv out and cleaned it, no change; wondering if the wiring could be the problem, or the brake booster line? Got to get this car running; summer is here!!:)
thanks for any help,
jm

[Jaxx_]

An engine meds more fuel when it's cold. The fact that your warm idle hunts also suggests the motor is lean. Look at fuel pressure and fuel delivery

[2002jm]

running rich???

An engine meds more fuel when it's cold. The fact that your warm idle hunts also suggests the motor is lean. Look at fuel pressure and fuel delivery

Seems like it is running rich, but I will check it out,
thanks for the input,
jm

[2002jm]

think I fixed it

So I was messing around with the m20 engine tonight and thought; why not unplug the afm.
So I did this and it starts and runs great. No idle problems, very smooth idle....how can this be true. I thought it would not start with the afm unplugged??
Any ideas?
jm

[2002jm]

spoke too soon:)

Well, the car starts and idles great now with a different afm, but if I rev the engine, it dies; so something else is wrong:)
jm

[2002jm]

vent hose for valve cover

The idle is high; assuming vac leak; found a major hole in the valve cover vent hose and the hose was also leaking at the throttle body...maybe that is the problem:)
Ordered a new one; mine fell apart when I tried to take it off:)
jm

[e30davie]

m20 and air leak = disaster. (well any engine on air flow meter)

I have had a hose clamp that seem tight but 1/4 more of a turn fixes an idle misfire.

[2002jm]

yes

m20 and air leak = disaster. (well any engine on air flow meter)

I have had a hose clamp that seem tight but 1/4 more of a turn fixes an idle misfire.

I can't believe how vac leaks mess up these cars:)!!
jm

[2002jm]

think it is fixed

So after replacing the vent hose on the valve cover to throttle body, and replacing the valve cover gasket, the car starts and runs good:)
The hole in the vent hose was under the intake where I could not see it and the hose was like rock!
So, vac leaks are a problem whit these engines:)
thanks for all the input,
john