E85 - 13:1 (gasoline AFR) - ACK!
Nov 30, 2008, 07:46 AM
#16
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 $$$$ housing?
My suggestion would be to pull a plug. If all looks normal, it is, and don't even worry about a compression test.
Razorlab, how did you end up fixing your fuel filter? Did you remove the OEM one and run an inline or replace the whole $$$$ housing?
Nov 30, 2008, 12:20 PM
#18
Nobody else running E85 locally has had this issue yet (knock on wood)
Filter assembly part #MR571545
Do yourself a favor and get a new rubber grommet (from fuel pump to assembly) as well. Mine was torn and I still need to get a new one. #MR431121
Last edited by razorlab; Nov 30, 2008 at 12:23 PM.
Nov 30, 2008, 02:54 PM
#20
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.
Nov 30, 2008, 06:15 PM
#25
I richened up the AFR in the fuel table by 1 full AFR point at loads > 140 and took the car out for a drive. The two WOT logs now show AFRs going to about 11.4:1 AFR at ~4000 rpm and leaning out to 12:1 at 7000 rpm. Much better, but there is obviously something going on. Hopefully its just the filter.
The part throttle bucking at moderate boost is gone too. I'm very curious about what is happening in the engine when the bucking occurs. Is it detonation or really fast burn causing the effective timing to go way past MBT? Or is it some sort of lack of full combustion at lean AFRs. Hopefully, its the latter, but it would be good to understand this kind of thing for future tuning expertise with E85.
The part throttle bucking at moderate boost is gone too. I'm very curious about what is happening in the engine when the bucking occurs. Is it detonation or really fast burn causing the effective timing to go way past MBT? Or is it some sort of lack of full combustion at lean AFRs. Hopefully, its the latter, but it would be good to understand this kind of thing for future tuning expertise with E85.
Last edited by mrfred; Nov 30, 2008 at 08:27 PM.
Nov 30, 2008, 10:19 PM
#27
plugs
Here's a picture of the plugs. All except #4 are a very light color, almost white. There is a speckle texture on the ground strap and on the exposed areas of the insulator. It doesn't appear to be erosion but instead a thin buildup of something. The texture almost exactly matches an earlier picture of my plugs when I was running gasoline. I also peaked into the cylinders. What little I could see of the top of the pistons looked perfect. I could easily see the machining marks on the top of the pistons. No erosion of any sharp edged surfaces on the pistons. I think I may buy a cheap fiber optic for this sort of thing in the future.
plugs after many (~20) WOT 13:1 AFR runs
plugs after ~10k miles on gasoline with typical WOT 11:1 AFR
plugs after many (~20) WOT 13:1 AFR runs
plugs after ~10k miles on gasoline with typical WOT 11:1 AFR
Last edited by mrfred; Nov 30, 2008 at 10:24 PM.
Dec 4, 2008, 08:43 PM
#29
According to Autocenter.net MITSU does sell the fuel filter separately for $4.93. It is item #20 on the attached diagram. Has anyone actually bought this filter and proven that it can't be replaced?
I think $107.04 for a new fuel filter by buying the entire assembly seems pretty extreme.
MrFred did you change your fuel filter yet? If so, did it affect your AFRs?
I think $107.04 for a new fuel filter by buying the entire assembly seems pretty extreme.
MrFred did you change your fuel filter yet? If so, did it affect your AFRs?