virgilr

Back again- this one is strange.

1996 EX-R (Candian EX) F22B1, A/T, 4 door.

I've set the base idle properly as per threads and FSM, etc. The IACV holds idle properly when accessories come off/on, A/C off/on, etc. FITV seems to working nicely- winds down from around 1500 rpm to base idle of around 700 (best guess by the dash tach!) when engine reaches temperature.

However, when the air temperature becomes hot (more than 30c/85f), the base idle drops to around 500 rpm once the engine reaches temperature. This doesn't seem to bump up after driving it for a bit. THE IACV again holds that idle under the various load conditions, but it's just a bit low for my liking.

Any ideas? Maybe the FITV is leaking around the wax ring when it's warmer outside? I know this should cause fluctuation/or rough idle, but it seems to be smooth still.

Got me confused, this one- maybe some other sensor?

YeuEmMaiMai

have you verified that the car is not running warmer than it should?

virgilr

Temperature seems to be holding nice and steady- I did buy this car used, but it's only about 1/4 the way on the temp. gauge- it can move up to about the 50% mark when idling for a while in park with the A/C on, but it doesn't seem to be running hot at all.

This happens right after it's come up to temperature after first starting the car, and stays that way while I'm running it.

Schmitey

The temperature issue makes me think its a stuck relay...a common problem on this gen. Is there a relay on this car that controls idle? I'm pretty sure there's a fan relay...

just a thought...I don't make any claims on knowing what I'm talking about come this one.

virgilr

I have replaced the IACV on the car with a wrecking yard part- had some surging idle problems before. That all cleared up when I put in the replacement part. I also checked the FITV, made sure the wax ring was tight.

The fan does cycle off and on properly. I assumed that the electrical load sensor would provide signalling when the fan cycles- the IACV seems to be holding the idle when the fan cycles, although I do see a slight dip.

Is there another signal that comes off this relay to the ECM when the fan fires?

jabontke

This is interesting and well posted information, virgilr. I am stumped myself, but it sounds like when the car goes from open loop to closed loop your problem occurs. In closed loop, the ECU ctarts a more dynamic control of the engine and stops uysing a preset warm up cycle. It might be beneficial to look through an emissions guide and see what changes as the car enters closed loop.

For those confused: Open loop is when the ECU uses a preset fuelk/timing map to warm the car (also does not use some emission devices) and Close loop is when the ECU uses the O2 sensor to adjust the AF ratio and uses most emission devices.

virgilr

jabontke-

Thank you so much for pointing me in a particular direction. I do have a PDF of the FSM, but I'm not sure if there is a detailed testing/troubleshooting chart on the emissions systems.

I am the third owner, and given the high mileage (175k plus), I'm not sure when any service was done to the 02 sensors or other emissions points. I'll try and test the sensors, and see if they're within spec. Given the age of the car, this could be at issue.

Great community- I do appreciate that you've taken the time, each and everyone, to actually write a response!