Honda civic idle problems.
10-08-2017, 12:43 PM
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Honda civic idle problems.
I have a 99 honda civic LX, with an automatic transmission. I have read many posts looking for my problems, and I seem to have some from some posts, and some from others. Also conflicting data per post as to whether or not my vehicle has a FITV has left me feeling confused.
Current symptoms:
1) Idling at 1200 ish, with small fluctuations (1-200 rpm every few seconds), after the car is warmed up and fans kick on.
2) If I cover either of the holes inside the throttle body after the car is warmed up it drops down to the specified 750 +- 50 rpm.
3) If the throttle is used and a certain RPM/ speed is maintained the car begins to jerk, changing rpms very rapidly back and forth, (around 2 change cycles per second up then down). This is while parked and holding the gas pedal steady, if driving the entire car jerks very fast, jittering, but only when maintaining any given speed. Acceleration or deceleration is a smooth transition.
Things i have changed recently (last 6 months):
1) muffler rusted off the exhaust pipe, new muffler
2)Replaced the ignition switch
3)Replaced the distributor for spark plugs + replaced spark plugs and spark plug wires.
4) Replaced the IACV with a brand new version from auto zone.
5)Bled and refilled the entire radiator with 50/50 fluid.
6) Have had a mechanic check for vacuum leaks, before the distributor was replaced.
There is a known problem that I'm not sure how to fix myself yet, nor do I have the funds currently. There is a crack in the exhaust manifold, perhaps a hairs width, and an inch long in the center between the middle 2 exiting pipes. Since its outward flow though I did not think this was the problem, and because it has been there since I bought the car 6 years ago.
I was going to turn the idle screw on the throttle body down for the high idle, when I found out maintaining any rpm with the gas pedal above idle causes the engine to jitter.
I need advice on how to proceed.
**I am new to engine mechanics but I'm learning as I go, and I'm trying to learn, so bear with me if I have questions please.
Current symptoms:
1) Idling at 1200 ish, with small fluctuations (1-200 rpm every few seconds), after the car is warmed up and fans kick on.
2) If I cover either of the holes inside the throttle body after the car is warmed up it drops down to the specified 750 +- 50 rpm.
3) If the throttle is used and a certain RPM/ speed is maintained the car begins to jerk, changing rpms very rapidly back and forth, (around 2 change cycles per second up then down). This is while parked and holding the gas pedal steady, if driving the entire car jerks very fast, jittering, but only when maintaining any given speed. Acceleration or deceleration is a smooth transition.
Things i have changed recently (last 6 months):
1) muffler rusted off the exhaust pipe, new muffler
2)Replaced the ignition switch
3)Replaced the distributor for spark plugs + replaced spark plugs and spark plug wires.
4) Replaced the IACV with a brand new version from auto zone.
5)Bled and refilled the entire radiator with 50/50 fluid.
6) Have had a mechanic check for vacuum leaks, before the distributor was replaced.
There is a known problem that I'm not sure how to fix myself yet, nor do I have the funds currently. There is a crack in the exhaust manifold, perhaps a hairs width, and an inch long in the center between the middle 2 exiting pipes. Since its outward flow though I did not think this was the problem, and because it has been there since I bought the car 6 years ago.
I was going to turn the idle screw on the throttle body down for the high idle, when I found out maintaining any rpm with the gas pedal above idle causes the engine to jitter.
I need advice on how to proceed.
**I am new to engine mechanics but I'm learning as I go, and I'm trying to learn, so bear with me if I have questions please.
Last edited by canthinkofname; 10-08-2017 at 02:22 PM.
10-11-2017, 05:31 PM
#3
Honda-Tech Member
Re: Honda civic idle problems.
Make scertain spark plugs are gapped to oe spec.
check for vacuum leak, preferrably using smoke. It will point out even pin size leak.
Iavc could be bad, even from new. Stay with oem iavc. Used one can be had fir $30..
try cleaning, using carb cleaner, your old iavc. Remove gasket before spraying the iavc down, inside and out.
reinstall cleaned iavc and post back.
check for vacuum leak, preferrably using smoke. It will point out even pin size leak.
Iavc could be bad, even from new. Stay with oem iavc. Used one can be had fir $30..
try cleaning, using carb cleaner, your old iavc. Remove gasket before spraying the iavc down, inside and out.
reinstall cleaned iavc and post back.
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