Hello all, the past couple of weeks my 2002 Civic EX has been having problems, the problem only occur in the evenings, after its been parked outdoors in 70+ degrees temperature days, when I driving home. Mornings the car runs perfect (Garaged).

The car starts up fine, once the engine temp get to normal, the RPM will suddenly start to drop, fast and only for a sec, the CEL will pop up during that time, but goes away. It can occur during acceleration, cruise, or deceleration. At stop lights the car will sometimes will nearly stall, or completely stall. The car has gone into "limp home mode" 3 times, slow acceleration, tach and temp gauge stops working, with CEL on. But if i pull over and restart the car it works perfectly normal.

If I shut the car off and scan it when I get home, it shows no code. Once with it was in "limp home mode" and I drove the car home and scanned it the scanner says it cannot connect to ECU (using snap-on blue point scanner). I've tried changing the alternator, thinking that there is a voltage spike causing it to go in to limp mode. But that didn't work.

Lucky when driving home one day I caught the RPM drop and limp mode on camera. The car doesn't stall when it goes into limp mode. You can hear the pitch change in the engine. Any help would be nice. I don't want to spend a fortune trying change things that aren't broke.

 

Check grounds and diagnose for a bad ECM/PCM.