80s Honda giving PGM-FI constantly red

Maintenance/Repairs
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21

@shadowfax - are you saying that if I reset the ECU after the warmup and the code 1 already thrown, I can verify if it “remains in open loop rather than switching over to closed loop”?

@GeorgeSanJose - thanks and you rock

22

No. I guess my verbiage was a little misfumbleful there. :wink:

If the CEL is coming on right after you start the car when it’s cold, and it’s throwing the oxygen code, then it’s weird because the computer doesn’t even look at the oxygen readings until the engine is warm.

If on the other hand you start the car when it’s cold, and then go do something else (like verify the fuel leak was fixed) and by the time you get back to the driver seat the engine has warmed up and you see the CEL on, THEN it would make more sense. In that case, the light probably came on after the car was warm. The computer went to poll the oxygen sensors and detected a problem with the circuit, so it threw the code.

23

OK - CEL comes on 9 mins to 20 mins into the driving
Earliest had been 9mins into the driving

But subsequent drive in the day never throw the code at all on the dash - but of course ECU keep flashing. I have also reset the ECU.

24

My Test Report:

  1. Had ECU reset lastnight
    Took the car for test ride around 1pm w/ outside temp around 64F
  2. 10mins into the drive the CEL came on - solid red (always)
  3. Turned off the engine and turned it on to make the dash light to go away - drove about the same distance and CEL did not come back.
  4. Reset the ECU and drove about 30mins - CEL never came back on.

Another test report at 6am:

  1. Had ECU reset previous night
  2. 10mins into the drive the CEL came on at about 6am
  3. Turned off the engine and turned on and drove (ECU wsa not reset)
  4. CEL came back on
  5. Turned off the engine and turned on and drove (ECU wsa not reset)
  6. CEL came back on (total of 3 times it came back on) - reached the destination (did not reset the ECU) - drove again at 2pm - CEL never came back
25

The problem has stopped - I used the Red Line Complete SI-1 Fuel System Cleaner below - CEL stopped for a day and then it came back and remained for about 70 miles - now it had stopped for a week - hoping it will last:
https://www.amazon.com/Red-Line-Complete-System-Cleaner/dp/B000CPI5Z0

Unsure if the heavy rain has anything to do with the issue

26

Update:
It is doing fine so far - no issues whatsoever since I used a bottle of Red Line Complete SI-1 Fuel System Cleaner.

I plan on using it every 10k on my cars that have over 100k mileage.