I have posted some of this before but have not solved problem yet.

1990 CRX DX 5 speed with MPFI swap(after the swap is when this started) getting CEL code 1, oxygen sensor, after driving for 5-10 minutes at 3000 or more rpms. No CEL if I keep under 3K, but I commute on the interstate 42 miles one way to work everyday and 3400-3500 is where I would like to run. I live in Louisiana and it's been hot lately and my A/C does work so when I ran it last week(and this week also) around 3500 rpms I noticed that the CEL did not come on my entire drive home. I have also driven below 3K(without A/C) the entire trip with no CEL.

So, what does running the A/C or staying below 3000 rpms do that would change the conditions related to the o2 sensor?

I have changed the o2 sensor, checked my grounds, tested my wiring, checked the timing, used injector cleaner, changed plugs, and I have a brand new distributor.

 

is your fuel pressure regulator in working order? if your fuel pressure is too high, you can run rich and foul the o2 sensor quickly.. which may or may not be your problem. i would check that, since it isnt on your list.

did you clear the code 1 after you got a new o2 sensor?

also, what ecu are you running?

 

I did clear the code after each attempt to fix this problem. I'm running a stock pm6 and everything from a 90 CRX Si that I used for the swap, except for the Distributor King dizzy.
I don't have a fuel pressure gauge to check the pressure with. Is there some other way to check the regulator?


Modified by rustbucketrex at 9:13 PM 6/19/2007

 

TTT

 

you can buy a fuel pressure guage in the for sale forum for like $35 or $40.. that would be the route i would go, or take it to an auto shop and have them just give you a reading. i doubt it would cost more than like $10 to have them find out your fuel pressure.