My 92 civic with 225,000 miles has just started to idle bad. It doesn't die but it sputters badly, sounds almost like the car is not hitting on all cylinders. There is no check engine light. I am also getting horrible fuel mileage compared to before. The car seems to run pretty good when I am giving it gas or after it warms up. I am not sure if its an injector or the distributor. I recently had the distributor, plugs, plug wires and water pump replaced (about 6 months ago) and the Valve cover gasket was replaced 2 months ago.

 

oK, There are a few possibilities. First the easy. There could be some air in the coolant system which will cause the car to idle rough. Most likely you have the same problem i do. Its most likely got to do with the timing belt. My car idled rough, and once she warmed up. it was all good. Then the timing belt snapped the other day. When is the last time the timing belt was changed? I would most lilkey take the car in to get that done, because if it snaps on you like it did on me, you are going to be in the need for a new top (head) part of your motor. Definetly get thise checked out, this way if it IS the timing belt you can get it fixed before it snaps.

 

The horrible gas milage and the fact that it runs Ok on the throttle makes me think it's a bad injector.

Do you have a Helms or a Haynes manual? Check the voltage across the injectors. Unplug them one at a time while it running and see if the idle changes.

 

Bad injectors scare the crap out of you--it'll feel like the car is sputtering even when you're coasting at freeway speeds.

If the timing belt hasn't been replaced, that'd be something to certainly do seeing that the car has so many miles on it (I'm hitting 170k within the next week and scared to death of 200k!).

 

check the iac valve. When a car has bad Idle it can be injecters, timing belt, coolant, iacv, and distributer but if runs fine when you push the gas you could have a bad iac valve. alot of ek civics have the same problem after doing motor swaps. The iac valve is the idle air controle valve and I controles your idle. Try one of those and also check you vacuum lines for small holes or cracks.

 

pcupo12- As far as know the timing belt has never been replaced. If it was changed it was before I bought it. (150,000 miles ago)

I checked the coolant levels and it was about 1/4 gallon low in the radiator and the overflow tank was completely empty. When I started it this morning it still idled a little rough but not as bad as before. Is there anyway to get the air out of the system? (if there is any in it)


Street Sniper- I am not very familer with the Civic engines, if I get the Haynes manual will it explain how to check the voltage at the injector? Should I unplug the injector when it is idleing bad or when it is idleing correctly?


shellebelle- I have notice that I have a slight power decrease when I am accelerating uphill in 4th gear. My car didn't come equiped with a tach but it happens in the mid to upper RPM range right before I shift to 5th. Could that be another indication of a bad injector.


94zchatch- Where do I find the IAC valve and how should I check it? I visually checked the vacuum lines and didn't see any cracks or holes. Is there a more effective way to check them?

 

there is a bleeder valve. Get a haynes, it shoes details how to do it. Its easy, u just start the engine and twist a screw.

 

the iacv is mounted on the back of the intake manifold right by the throttle body. The only way to check it is to get a new one and try it. Or if you just want the bad idle to stop get some gasket maker sheets (paper ones) and slide it between the iacv and theintake manifold covering the two holes.

 

just take off the radiator cap and let it idle the air should be pushed out. as far as the bad idle, you might have some water in the gas tank i had a car that idled rough so i put some of that gas dry stuff in the tank and it really helped.

 

UPDATE: After talking with a local mechanic, he informed me that the head gasket was blown and letting one cylinder fill up with coolant while the car was turned off. Then after the car was run for a little while the coolant would be expelled from the cylinder and the car would then start running fine. He advised me that it would cost more than the car was worth to replace the head gasket. He said that a cheap temporary solution would be to put some Bars stop leak in it and it might seal the head gasket.

Saturday I went and bought a can of stop leak and put it in the radiator and I also let the car idle for about 30 min with the radiator cap off. As someone here told me there was indeed some air in the system, as I had to keep refilling the radiator. After I was done I let the car set overnight and started it Sunday morning. To my surprise the car ran fine with no idling problems.

I know this is no permanent solution but it may get me by for a while, at least until I can afford to buy another form of transportation. I would like to thank everyone for his or her help. This is truly an informative forum.