Erratic Idle

[jamminn07]

I recently purchased an 86 MR2. The car mechannically is sound however, until it warms up, the engine revs from approx 500-1500 rpm. Any ideas?

[TokyoRacer]

Could be EGR related, if that car has an EGR

[MKI_S/C]

theres air in your coolant system that is what gives the unconstant idle until the thermostat opens and the air is moved through the system

[MR2Jedi]

When you starting the engine cold, it is normal for the idle to be 1200-1500rpms until it reaches a sufficient operating level. Do the RPM's drop after it's warmed up?

[Zz_005_zZ]

I would try MK1/SC 's idea first and foremost, bleed the radiator of all air, which is not an easy task, but at least it won't cost much!!

[tHa kNiGHt FaLL]

Originally Posted by jamminn07

I recently purchased an 86 MR2. The car mechannically is sound however, until it warms up, the engine revs from approx 500-1500 rpm. Any ideas?

it only idle erratic at idle when the car is cold...?

when its warm it doesn't do it at all...?

i'm thinking something along the lines of ISC is stuck or not working at all...


its early in the morning... but i'm having trouble seeing how air in coolant effects idle...
air in coolant would effect the expansion process and cause a heating/cooling issue.

ISC allows air to bypass the throttle plate in cold start situation...
also i dunno the 4age setup but check to see if you have a cold start injector... it will be in the intake manifold. check the resistance across it... i don't own an AW11 so i don't have a manual to check the specs but i'm sure you can find it online

some more info please and maybe we can narrow it down