M20 idle woes

[ThatM20Guy]

Didn't really want to start a new thread over this but couldn't really find another scenario quite like mine. The car seems to idle fine when it is up to operating temperature, but on a cold start it seems to run rich on the low end and then die.

Things I've checked so far
- Refurbished ICV installed
- TPS seems to be working correctly
- 95% of vacuum leaks solved
- Cleaned AFM

Only other thing I could think it would be is a dead coolant temp sensor. The car has new plugs with only about 40 miles on em (if that) and injectors seem fine.

The only other intake leaks I know I have are on the metal elbows that attach the vacuum lines from the booster to the throttle body. They have just worn out their press fit and no longer stay in tight. Is it safe to JB weld these back into place or is there a better option?

[e30davie]

yah you wanna fix all vacuum leaks, JB weld seems to be the way to go on those fittings from reading others experience.

AFM engines just can't deal with vacuum leaks. your engine is more susceptible to vacuum leaks when its cold, once its hot it can put up with a slightly leaner mixture at ldle.

[ThatM20Guy]

yah you wanna fix all vacuum leaks, JB weld seems to be the way to go on those fittings from reading others experience.

AFM engines just can't deal with vacuum leaks. your engine is more susceptible to vacuum leaks when its cold, once its hot it can put up with a slightly leaner mixture at ldle.

Thanks for the info. I'll JB weld those fittings this weekend and see if that doesn't fix it.

[zaq123]

Only other thing I could think it would be is a dead coolant temp sensor.

I think this is your issue. Also check connector to it, could be corroded or just bad connection.

[zaq123]

http://www.e30zone.net/e30zonewiki/index.php/Blue_Plug

[ThatM20Guy]

Thanks for the link. Going to try the JB weld first and see if that helps at all and then go ahead and replace the coolant sensor.

[Shock(/\)ave]

Once you get the vacuum sorted out, I would definitely try the coolant temperature sensor next. I keep a known good one on hand along with a clean idle control valve for M20 idle troubleshooting purposes.

I'd then check your fuses, battery terminal connections, C101 connector and grounds. The majority of idle issues I've encountered that weren't simple fixes were related to issues with the electrical system.