my cars idle goes up and down constantly from 2k rpm down to like 700..
what should icheck for
car = 1991 crx si
motor = d16z6 with d16z6 intake manifold...
ecu = pm6 ecu.

 

02 sensor, vac lines, TPS voltage, and your iacv(or whatever the ---- it is). Those are the only things I could think of.
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also...if you got a coolant leak or low coolant, it jumps it too.

 

so when warm the idle jumps from 700 (normal) to 2k.

what about cold?

is it a constant jump, does it happen all the time 700 to 2k to 700 to 2k just constantly goes.??

 

constantly when warm

 

FALLLLLLLLLLLLLL DICKHEADZ!!!!

hahahhahh

 

so cold idle is rock steady.

try burping and checking the coolant.

 

how do you burp your coolant?

 

first of all we need to know what burping is and why. Burping the coolant removes air pockets in the fluid so that the Fast Idle air control valve doesn't see these air pockets and interrpret them as a cooler substance and then raise the idle thinking the car is cold. There should be a procedure in your service manual explaining how. But if I remember correctly you would open your rad cap and then start the car and then give the upper rad hose a squeeze. keep doing this until it just raises the fluid and no bubbles come out.

But dont do it so long that the car warms up completely.