Hi all, New to the forum but need some help. I have an 04 civic ex, my CEL has been coming on and limiting the car to 4k RPMs. The amount of time after resetting the ECU that the CEL comes on is not consistant, sometimes it will come on after a mile, sometimes i can drive for 15-20 mins. Also the battery idiot light occasionally flashes. Have been looking for a short for this. All electronics in the car appear to be working properly - int and ext lights/signals, radio, windows, ect. No problem starting and runs fine, but is limited to 4k RPMS... I had the codes pulled about a month ago but will get them redone tomorrow as i cant find the results right now. What i am wondering right now is: Could an intermitant elec. problem (i.e. short)cause the CEL to come on and rev limit to 4k. Also what other info would help diag the problem? and where can i find this info. This is my first civic, I've had it for about 18 months. I love my car but it's very frustrating not being able to drive it.

 

Go to an auto parts store to have the codes pulled and the alternator/charge system tested. Post the results.

 

I agree with Ron, But as for you wondering if it can limit your revs, Yes Chances are (im no expert but) Its throwing your car into "Limp-Mode" a fail safe feature that kicks in if the ECU thinks something is wrong, and it does exactly what its called, allows you to limp your car, but thats it, Limiting the chance of a catastrophic failure. Like i said, Im no expert but pretty sure i can say that with confidence.

 

OK here's what i got today. Started this morning by resetting ECU. Drove to work (10 mins) no CEL. ran around at lunch time (30-45 min of driving) no CEL. the whole morning i was babying the car, not going above 3k rpm, accel and braking gently, ect. At the end of lunch my CEL was still off so i went and had my emissions done. Passed E-test. at this point i figured i should quit babying it and drive normally. The first time i hit about 3500 RPM CEL came on. Had the codes pulls and got a P2646. the battery and alternator both tested fine. starter had a low voltage but i havnt had trouble starting even in the cold, so i figure the starter can wait.
I have checked my oil level and its OK. is the oil pressure switch the next thing to check?
Thanks for the quick responses, I am eager to learn more about my car.

 

This all started after my timing belt went out and i had to get my valves replaced. I'm guessing they did something wrong when they put my car back together.

 

Do you still have a VTEC head on your engine? They might have replaced it with a non-VTEC one. Also check that the VTEC solenoid and switch on the end of the head (near the intake and transmission) are plugged in.