1990 Civic CEL/ECU Problems?
 

Having some problems on my son's Civic. It's been over a 100 degrees here and the CEL has been coming on. If you check the LED on the ECU it's 1 lond flash and 16 short flashes. If you put a jumper wire in the 2 prong plug to check the stored code it does nothing. Also, it occasionally won't start. It will crank and crank but won't start. When it cools off outside the car starts fine. Please help! matt

Re: 1990 Civic CEL/ECU Problems?
 

On 88-91's the codes are checked via the LED on the ECU. The connector is only for setting ignition timing.

Re: 1990 Civic CEL/ECU Problems?
 

hmmm.. yeah he is right about he blinks try counting again.

I had a ef civic hatch back in high school that wouldnt start if it was hot outside, would just crank and crank

but if it was a cold early morning she fired right up but no codes.....never did figure that one out

Re: 1990 Civic CEL/ECU Problems?
 

sounds like you, if you are counting correctly, have codes 1 for O2 sensor and 16 for fuel injector circuit - OBD0 D-series ECUs do not have long and short flashes, only short - make sure that you are counting correctly - the symptoms you describe would be consistent with a bad ignition control module (igniter) which would be a code 15 - ECU flashing 15 times - could also be a bad main relay - i would start by checking main relay

http://i38.photobucket.com/albums/e1.../ECUcode-1.jpg

Re: 1990 Civic CEL/ECU Problems?
 

Try replacing the PGMFI relay. My 1990 STD did the same thing when it was hot out sometimes I would drive to a store run in grab a soda come out and it wouldn't start, I replaced the relay and haven't had an issue since.