87 CRX SI FI starting/idling trouble

[SteveChism]

First I'd like to apologize for the long winded post, i wanted to give as much detail as possible.

Ok, so i've searched through this forum trying to find similar cases to mine but i can't find one that matches fully. My CRX has had idle trouble since i got it about 8 months ago...idling high on startup, surging randomly, and every once in a while the PGM-FI light will pop on and the engine acts like it's missing a cylinder. I checked the ECU when the PGM light was off and it was showing OXXO...coolant sensor, and when the light was on it was showing XXXO...oxygen sensor.

The fuel pump was whining a bit and from what I read here, I decided to replace it and the filter, but the big problem still persists: without any discernable trigger, the engine will run very rough on startup and die shortly thereafter. Once it dies it tries to start when i crank it only turns over once or twice then goes to a dry crank.

My questions are these:
could the oxygen and coolant sensors be causing such problems with starting/idling and,

I've read here that there are 2 coolant sensors, one on the thermostat housing and one in the block...where is the one in the block located? it isn't in my haynes manual and,

advance tells me there is an upstream and downstream O2 sensor...haynes only details the one on the manifold...is there a second one and if so do i need to worry about it?

Thank you all so much for taking the time to read

Steve

[lxndr]

The surging idle is due to the IACV (idle air control valve) located on the backside of the intake manifold. Some people have had success cleaning it out with carb cleaner, but I've never been so lucky and always end up replacing them. However, since the coolant temp sensor and IACV are part of the same system, try replacing the temp sensor first (especially since this is what you're getting an ECU code for).

The cold/high idle circuit is controlled by the temp sensor, IACV and ECU. The ecu reads the temp sensor then tells the IACV when to close. If the temp sensor or IACV are faulty, then you end up with surging idle.

It's been a while since I've worked on an stock motor, but I believe both coolant sensors are located on the side of the cylinder head. 1 is for the ECU to monitor and 1 is for the temp gauge.

Don't believe the guy at Advance, you already know more about your car than he does. Your car only has one O2 sensor located on the exhaust manifold.

[iristhirteen]

Originally Posted by SteveChism

First I'd like to apologize for the long winded post, i wanted to give as much detail as possible.

Ok, so i've searched through this forum trying to find similar cases to mine but i can't find one that matches fully. My CRX has had idle trouble since i got it about 8 months ago...idling high on startup, surging randomly, and every once in a while the PGM-FI light will pop on and the engine acts like it's missing a cylinder. I checked the ECU when the PGM light was off and it was showing OXXO...coolant sensor, and when the light was on it was showing XXXO...oxygen sensor.

The fuel pump was whining a bit and from what I read here, I decided to replace it and the filter, but the big problem still persists: without any discernable trigger, the engine will run very rough on startup and die shortly thereafter. Once it dies it tries to start when i crank it only turns over once or twice then goes to a dry crank.

My questions are these:
could the oxygen and coolant sensors be causing such problems with starting/idling and,

I've read here that there are 2 coolant sensors, one on the thermostat housing and one in the block...where is the one in the block located? it isn't in my haynes manual and,

advance tells me there is an upstream and downstream O2 sensor...haynes only details the one on the manifold...is there a second one and if so do i need to worry about it?

Thank you all so much for taking the time to read

Steve

I liked the way you were so detailed about what is going on because my 87 crx si is doing the exact thing, one other note the fuel pump whines real loud...did you come to any conclusions on what you fixed or replaced..i would greatly appreciate any help you have to offer. Thanks