I have an 89 Civic LX 1.5L fuel injected, 167k, with automatic transmission. When I bought this car the owner had just done a full tune up and replaced the transmission fluid and had all the service records to prove it and all previous maintenance however he would not let me keep the records because they had his credit card info on them.
Anyway, the car ran fine for a while, though it always idled at about 1000-1500 rpm, passed emissions with flying colors a few months ago and then just the past month or so it's been idling erratically when in neutral or park and warmed up. It will jump (actually more like pumping the throttle than a jump, it smoothly accelerates up to 2500rpm then drops to 1000-1500rpm and repeats) from 1000 or 1500 to 2500 rpm up and down as long is it's in neutral or park. When started cold it idles at around 2000 until it warms up then it acts as above.
When cold and in gear it surges when you first start out, it's about the same behavior as when in neutral and hot a smooth acceleration up to 2500 and then a drop and repeat.
Now, when I bought the car I was told that it needed a valve cover gasket and it leaks a little oil, presumably from the valve cover, when hot. I have not fixed this gasket.
I replaced the air filter and the pcv valve as those were the cheapest fixes in the Haynes manual, but they didn't fix the problem.
Could this be a vacuum leak from the valve cover gasket? That's what my dad thinks.
Or could it be related to the transmission somehow, why else would it only do it in neutral and park?
The Haynes manual also mentions the EGR valve causing idle troubles but I can't afford the buy one and try it out if it won't definitely fix the problem.
Can an auto parts store or mechanic pull codes for my car so I could tell if I have a sensor problem? I only know about the little trouble light under the passenger side floor mat because I checked one on my other 89 civic when the check engine light came on.
Thanks for such a wonderful site and thanks in advance for your help.
Friday, October 26th, 2007 AT 5:47 AM