- This topic has 14 replies, 5 voices, and was last updated 7 years, 10 months ago by
.
-
Topic
-
I am stumped on an issue with my 2002 1.7L civic and I am hoping someone has some suggestions. I recently had a coolant leak and replaced the head gasket after getting the head machined. I also replaced the timing belt and water pump while I was at it and replaced the exhaust manifold. Everything is working fine and I am not throwing any codes since the repair job but the car vibrates at idle and if I hold the gas pedal to maintain 40 miles per hour (while driving) I notice an rpm hunt of about 100 rpm. So far I have cleaned the idle control valve, tested for vacuum leaks and replaced the O2 sensor and spark plugs. Still no change. I have double checked the valve lash but the timing is perfect and the adjustment is good. Any suggestions on where to go next would be appreciated.
-
Replies
-
You could have a misfire going on.
https://www.ericthecarguy.com/faq/solving-automotive-performance-issues
Thanks, I thought of that but it runs too perfectly at high speeds and runs “smooth” at idle even though there is a vibration (it’s not rough like a misfire). I suspect it is something I disturbed while doing the head gasket/timing and exh manifold but I can’t seem to isolate it. I have over 330,000 on it now so I suspect I will live with the speed hunt until it gets worse and throws me a code! I replaced the exhaust manifold with an aftermarket part but I don’t know if that could be the culprit (the cat looked smaller than the original)…
I used propane. Flex hose attached to a typical torch nozzle and introduced it around all my hoses – no change in idle.
Thanks, I really believed the problem was a vacuum leak and was dismayed when the propane test turned up nothing. I will try the smoke test to see if I can find a leak. All the symptoms sure point in that direction.
I have the same issue 60kmh cursing RPM fluctuate 100 RPM. Only 60 KMH. I notice this just after I replace the Tranny on this.
Very frustrating. I have done a smoke test and can’t find any vacuum leaks. I am considering changing the fuel injectors but hate the idea of spending $300 and still have the same problem. I still think it is something small that I am overlooking. Life would be simple if it would just throw a code.
Ideas:
Dirty MAF
Slightly dirty injectors – run an injector cleaning kit through them
Weak spark – distributor or coil on plugs? Check for misfires under threshold to throw a codeWell, I removed my MAP sensor to test it and when I tested the connection to the sensor I found that I only have 6V instead of 12 when testing my center ground connector (negative to center pin, red to positive terminal on battery) with car in on position. This leads me to believe I have a ground issue in my wiring harness which sucks because I hate chasing grounds! Chances are I disturbed something in the wiring harness when I removed the head to change the head gasket.
PROBLEM SOLVED:
After finding the bad ground on my MAP sensor connector I chased the wiring harness and found nothing wrong. Checked the ECU and all connections, still nothing. Then while staring at the engine and contemplating I noticed that a wire, which as far as I know is run out to the engine compartment for an accessory that is not on my car, had become jammed between my side engine mount and the chassis (the wire must have fell down while I was doing the timing belt) and I didn’t notice it there when I put the mount back on. This wire was obviously carrying a voltage since it played havoc on my emissions control system. Once I removed the mount and wrapped the end of the wire the problem was solved. Thanks to everyone who reponded.
- You must be logged in to reply to this topic.