Hi, I have a 2000 Civic DX with 137k miles that has an idling problem after it runs for about 10 min. The engine just keeps revving up and down. The idle also seems a little high before it starts up. The temperature gauge is also not working at all. It doesn't register at anything even though coolant is getting hot.

I bought the car after it was in a very light front end collision. The cover and bottom of the radiator where all that were damaged. I don't know any of the cars history other than that. The car currently is repaired and has a new radiator in it.

It originally would come up with a check engine code, I forgot the number but it was a tps malfunction. I tried changing the tps sensor but that didn't do anything. I've also tried the thermostat. When I first put the radiator in I left it running without the cap for about 30 min and filled it as it went down. I noticed there wasn't a bleeder screw and another site showed that is the correct way to bleed it.

A day later, I got a p0108 code which is a map sensor. I tried changing that and that didn't help at all either. There aren't any bad grounds or vacuum leaks that I could find.

Does anyone have any idea on what this could be? I am desperate for help and need it as soon as possible. If anyone could help out, I would greatly appreciate it.

Thanks

Do a propane enrichment test to check for leaks in the intake system. What happens is, when the car is warmed up (that would be about 10 min for you), if the throttle is closed and the rpms are above some threshold like 3k rpm or so, the ecu will cut fuel to the injectors. Generally this is desirable, like when you are coasting to a stop. When you are actually just trying to idle, and have a leak in the intake system, the map sensor will sense this extra air and supply more fuel, which makes the engine revs rise until the fuel cutoff threshold is reached.

This propane enrichment system is a test I haven't heard about. It sounds perfect for testing for leaks. Do you go to the garage to get this propane test? So the extra air is found on this test. Then hopefully you can get the leak fixed. The idle should go back to normal after this.

Sounds like a vacuum leak or your cold start injector. Cold start injectors fire only when the motor is cold, and sometimes can drive the idle up and down erratically and then drop to normal after heat up. You can disconnect the cold start injector for simple eliminations to remedy the problem and if not re-connect it. The cold start injector really is for cars/people who live where it is very cold and could use a little fuel enrichment for start up. Sometimes in old cars the cold start injector itself leaks more than what is supposed to, causing funny idle(more fuel).

Could it be water in your fuel, that would produce a TPS code... also with the afore mentioned front end damage... you may need to have the timing belt replaced.

This post has been edited by NV 05: Apr 23 2008, 05:06 PM