My car has been somewhat jerky during part throttle accel in 2500-4000 rpm range for the last several weeks. I had been ignoring it because WOT runs were smooth, and hey, its E85, but then I did a few logs this evening, and to my surprise (or shock), AFRs at part throttle and WOT at high loads are about 13:1 (gasoline AFR) when I had tuned 12:1 (gasoline AFR) several months ago. There was an occasional 1-2 knock count during the runs, but I'm still a bit worried that I may have done some damage. Need to do a compression check tomorrow.

 

That is wierd, they should be transitioning to the winter blends (or have been the past few months), I would think you would become slightly richer do to that lower ethanol content.

 

oof, I got a surprise like that one time when my FPR hose blew off at 30psi on 93 octane...luckily I noticed it on the WB02 gauge and let out.

 

The E85 supplier in town blends their own E85, and the keep the same ethanol/gasoline ratio year-round.

 

13.1 is not all that terrible..I'm sure the car is just fine man..But I would look into what it causing it to go so lean..I don't have an afr gauge either, but it is situations like this that make me want to get off of my keister and install the one sitting in the basement..Mabye check your sock/filter, I know Bryan had some trouble with his and his car leaned out a bit..

 

well thats nice. I wish I knew what the ethanol content is of the fuel in my tank.

 

I think there's an ethanol content gauge you can buy just for that purpose

 

Yes zietronix makes it, then you have to buy the GM flex fuel sensor..

 

seems to me like it would be a wise investment to get a wb02 gauge and the zietronix gauge + sensor if you're going to run e-85 and deal with potential winter blend differences from station to station.

 

I think it's a great idea but that little sensor is ike 350 dollars..

 

pricey but way cheaper than a rebuild

 

Time to check your fuel filter (in the white plastic fuel pump assembly)

If you remember mine clogged and leaned the car the hell out.

Could be that, could be your ethanol % change, but I would imagine you would go richer but knock more if that was the case.

My afr has been rock solid going into winter (after getting a new filter) here in California.

 

too bad there isn't a cheaper alternative. It's well worth the price IMO.

 

Mabye one day when I'm ballin like you I keed I keed

 

Mrfred, I'm sure your engine is fine. I've done worse and my friends have done worse. My one friend was going mid 13's for a couple days on regular gas with a hole in a FPR line. The same friend was going mid 13's again after bringing his car out one spring on the old stale pump gas. I've personally went 13 flat for half a season of drag racing (30-40 passes). It was a couple years ago and widebands were still expensive and I was relying on a dyno tune. When I finally put the wideband in I said heck it, car was fast, and kept it "lean".

My suggestion would be to pull a plug. If all looks normal, it is, and don't even worry about a compression test.

Razorlab, how did you end up fixing your fuel filter? Did you remove the OEM one and run an inline or replace the whole $$$$ housing?