High idle

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HellaFlushHonda

New Member
I just got a '95 civic with a gsr swap & I am having trouble with a high idle. (2000-2500rpm) I have done all the obvious stuff, idle screw all the way in, no apparent vacume leaks, check thermastat on the iacv, check that the plastic ring is screwed all the way in on the iacv. Also, if it matters the car has a msd distibutor & coil. Any one got any suggestions? I am new to Hondas having just come over from the world of big carbd V8s.
 
I just got a '95 civic with a gsr swap & I am having trouble with a high idle. (2000-2500rpm) I have done all the obvious stuff, idle screw all the way in, no apparent vacume leaks, check thermastat on the iacv, check that the plastic ring is screwed all the way in on the iacv. Also, if it matters the car has a msd distibutor & coil. Any one got any suggestions? I am new to Hondas having just come over from the world of big carbd V8s.

That's the FITV. IACV is on the back or the intake manifold(it has coolant lines running to it; it does not have a plastic ring or thermostat in it). Try cleaning the IACV; also try unplugging it while the motor is running to see if there's a difference.
 
You are supposed to unplug the iacv when you adjust the idle screw. If you did not then it would not change the idle correctly.
 
Thanks for the help, I took the iacv off & sprayed it out with carb cleaner, but there is still no change. Is there any way to test the iacv? I tried unplugging the sensor while the car was running & all I got was a cel. It acts like there is a massive vacume leak, but I just can't find one.
 
while its running spray some brake cleaner around the intake.. If the rpms jump up real quick then you found the leak.. Just look for where the cleaner bubbles up and sucks in..
 
You are supposed to unplug the iacv when you adjust the idle screw. If you did not then it would not change the idle correctly.

This is true.....Helm's Manual for that motor says to get car to running temp....shut car off and unplug IACV wiring.....restart and the car should idle 450 rpm +/-50rpm (this is hard to tell on a stock tach.....digital like a smog shop is best). Then you can adjust the idler screw and get it to the desired rpm. Shut car off....plug IACV back in and unplug the Back Up fuse (in the fuse panel under the hood by Battery) for 15-20 seconds and plug it back in.

I tried unplugging the sensor while the car was running & all I got was a cel.

Helm's also states how to check if the IACV is bad. You need to get car to running temp and unplug the IACV electrical. If the idle drops (you will hear/feel it) then the IACV is working properly. If it doesn't drop rpm.....it needs to be replaced (per Helm's).

You have a 95 so OBD1....is the motor OBD1? Or OBD2 and made to work in your shell? I guess I want to know if you have an OBD1 or OBD2 Throttle Body? The OBD1 will have a FITV mounted to the bottom of the TB. Take the intake piping off the TB and start the car. You check the FITV (per Helms) by getting car to running temp. There is a breather hole on the bottom of the throttle body (inside the TB....you'll see it). Put your finger or thumb on it and feel for suction. If there is suction, Helm's says replace (but there are threads on how to tighten the plug/clean it). If there's no suction.....then its working properly.

Try those things......they are free.....just follow the steps.
 
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is the high idle fluctuating? sometimes IAC valves get stuck and they usually cause an idle surge. Also check the throttle cable adjustment, and throttle stop screw if it has one. you may have allready checked this but no one has mentioned it yet.
 
Thanks for the help, the carb cleaner did the trick. I had a chunk of intake manifold gasket missing, I replaced it & the idle dropped right down to 800rpm.
 
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