Hey,
The check engine light in my stock 92 SC300 has come on a few times. It usually comes on while Im driving and stays on until I stop and park the car. The next time I get in the car the check engine light is off and stays off. I've driven the car for about 8,000 miles since the purchase and the light has come on maybe 10 times.

So I take the car over to a friend who works as service manager at a Honda dealership (also very skilled DSM modifier) and he hooks up their Snap-On code reader. No codes are pulled. The check engine light was off at the time but there still should have been a log in the ECU of codes that had been thrown from before right? It did show that the idle switch was never turning on so I have to replace that. The next thing we did was try to induce a code by unplugging the throttle position sensor while the car was running. The car bogged a bit but no check engine light came on. Next we unplug the right O2 sensor, turn on the car and still no code is thrown. My question is, is the ECU bad? Has anyone else had this kind of experience with the ECU and sensors? My friend suggested purchasing a data logger so that I could catch the check engine light code when it comes on.

Looking forward to any advice.
Thanks,
Rasa

 

Pull the clip off the MAF while the car is off.
Try to start the car (it might start but will stall quickly).
An unplugged MAF causes an immediate persistent code.
If it doesn't catch that, somethings definitely wrong.

~Alan