I have a gsr swap in a crx. I've been using cheap 91 costco gas for a while and just recently put in a full tank (from close to E) of chevron 91 pump gas. Somewhere around a day later, I get a check engine light for code 43, but it drives completely normal. Vtec still hits hard. Actually runs better.

Any reason to this? Is it possible the fuel could have been contaminated? What even triggers the code? The o2 sensor? Is it possible that the chevron fuel is just cleaning up the all the old deposits which tricks the ecu or o2 into thinking there is a fuel problem?

 

https://honda-tech.com/forums/acura-integra-6/throwing-code-43-1990-integra-2798228/ and google around that's a hard one to diagnose the cause in my experience.

 

If you clear the code does it come back?

 

Thanks man. That thread gave me a few ideas. I'll keep filling with chevron for a few more tanks, see if the cel keeps coming up. It's pretty random right now.

 

I just cleared it right now, i'll let you know if it comes back on.

 

Alright, a little update here. The code 43 came back last night but i wasn't able to drive with it on for that long to check the symptoms. I felt like it lost some power, but it was really hard to tell. After two hours of sitting, turned it on and the cel was hidden. Drove home normal.

I just decided to do a valve lash adjustment this morning just cause it has been a while. Also checked the spark plug gaps and they were at 1.1. I read that Gsr's gap was 1.2-1.3 so i gapped to 1.2. Turned her on and sounded much healthier. Drove around a couple blocks and it seems fine. I'll be doing some more driving though and see if it comes back.