Idle issue.

[ak-]

Alright, I'm out of ideas.

I have a slight idling issue on my m20b25.
It goes up and down smoothly from around 600 to 900rpm on its own when at a stand still. If I get the engine warmed up, and drive it out for a while, the idle will go back to normal, but you can still see the tiny tiny idle revving up and down by 100rpm's or so..



Mentionables:
:: M30 afm.
:: Tuner Motorsport chip.

Solutions that didn't work:
:: Cleaned ICV with carb-cleaner. (worked for the time being, turned off
the car, turned it back on and same problem.)

What I think?
:: Need 19lb injectors to match M30?
:: Need new ICV?
:: Chip? Is anyone else running this combo?
:: Is the Computer trying to relearn the ratio every time I turn off the car? Considering it will idle out smoothly after a 30min drive.

Disconnecting the ICV makes the idle go back to normal, but yea.. I don't want to do that.


Thanks in advance.

-abby

[jlevie]

It sounds to me like you need to (1) have a smoke test run and fix the intake leaks found, (2) re-install the M20 AFM.

[blocke]

I had somewhat similiar issues. Check for vacuum leaks. Then spend 20 bucks from Pelican and buy a new coolant temp sensor, and thermostat switch. The DME runs off the coolant temp untill the 02 sensor warms up and it switches to closed loop. If the coolant temp is bogus, (as mine was), your car will run all kinds of shitty till it warms up. As soon as I put new one in, all my cold issues went away.

[Kershaw]

ooohhhh ffuccckkk, really?

thank you so much for that knowledge blocke.

i've had the coolant temp sensor disconnected since i did the engine swap and always wondered why the fuck it wouldnt start properly until i had cranked it/started it enough times so that the engine was a bit warm. i thought it was a cam issue. im going to go extend it tomorrow morning and see if it fixes anything. if it doesnt, i still eliminated one potential problem.

(reason: 86, but the engine is a 89+. coolant reservoir is on the other side. wiring was not long enough.)

[ak-]

It sounds to me like you need to (1) have a smoke test run and fix the intake leaks found, (2) re-install the M20 AFM.

I sprayed carb-cleaner everywhere today and didn't get anything.
I guess a smoke test is next.
My M20 AFM is long gone. Gahh.

Thank you!

I had somewhat similiar issues. Check for vacuum leaks. Then spend 20 bucks from Pelican and buy a new coolant temp sensor, and thermostat switch. The DME runs off the coolant temp untill the 02 sensor warms up and it switches to closed loop. If the coolant temp is bogus, (as mine was), your car will run all kinds of shitty till it warms up. As soon as I put new one in, all my cold issues went away.

Well, my car doesn't run "like shit till it warms up". It pulls hard and well at any given moment. It's just the buggy idle in the beginning, but I think that's what you might of been referring to.
Thank you for the info.



I'll post results when I get the test done.