Idle pulsing on 91 DX 1.5L DPFI

[gooddog]

I just picked up a DX yesterday and I'm having difficulty diagnosing my idle issues.

The engine is a 1.5L with DPFI and a vertical TP as oppsed to most ive seen on trouble shooting threads. here is a picture of the IM

When the car is running cool everything sounds good. as soon as it gets to temperature the car rapidly pulsates the idle speed. I've cleaned the IACV, Ive cleaned the entire IM and checked all vacuum hoses. and im pretty sure i dont have an FITV.

Im driving up to autozone or someplace close by to read my codes.
I will be checking my laptop while in the garage when I return. I want to fix this today. any help would be phenomenal.

 

[gooddog]

I jsut got back from several repair shops all without the proper tool to read my codes or only read if i agree to pay them to do the maintenance, which i can do myself. on my way home it dawned on me. Its fine until operating temp. then it idles like crazy. would that mean that my IACV is bad? or is there one more thing ive overlooked?

 

[gooddog]

Fixed it! I had air pockets in the coolant.

 

[CivicCowboy]

My 1989 DX 1.5L dpfi (D15b2) is doing the same thing. HOw did you fix the idle pulsing? Or anyone else that has had this problem and knows how to fix it?

 

[Hendo]

My 1989 DX 1.5L dpfi (D15b2) is doing the same thing. HOw did you fix the idle pulsing? Or anyone else that has had this problem and knows how to fix it?

Did you try reading the thread? He had air in his coolant.

 

[gooddog]

My 1989 DX 1.5L dpfi (D15b2) is doing the same thing. HOw did you fix the idle pulsing? Or anyone else that has had this problem and knows how to fix it?

Make sure your coolant has no air bubbles and make sure your throttle cable isn't too tight. These can both cause issues. If those don't help clean the IACV and bleed coolant after. If that doesn't help clean the throttle body.

d-_-b

 

[CivicCowboy]

Did you try reading the thread? He had air in his coolant.

In all the years of workng on cars(hobby not job) This is the first time I have heard of air bubbles causing any problems. My first thought when I read that was "And what does that have to do with the price of tea in China?"
So are you serious about the air bubbles in coolant affecting idle??

 

[gooddog]

Oh yeah air gets inside the idle air control valve and it doesn't know what to do

d-_-b

 

[Hendo]

Yep, had a leak in my GSR motor, screwed with the IACV, the fast idle solenoid and kept the thermostat from opening (from the air expanding and the pressure building up). Would idle all crazy high and sometime overheat a little from the stuck thermostat.