So the Hoe is having more problems. Running super rich with a very rough idle.
| Question of the day. What causes an 8 cylinder misfire under heavyload | ONLY at high rpm and mph?
V

VVVVVVVV Backstory VVVVVVVV
************** Called a guy I know with a laptop and he came out and ran some diagnostics. Turns out it was a failed O2 and he happened to have one in his garage sitting in a set of headers. fixed the problem or so we thought. a few days later on my way home from work, I got on it hard to get around a guy and it felt like I hit the governer. Except I have the governer tuned out. tahoe wouldnt gain any speed and would lose about 10 mph before it would try to get back in it. This happened a few more times before I saw him again. Only under heavy load / high speed. When I told him about it he ran back to his house grabbed his laptop and we hooking it up to the truck and hopped on the interstate. Truck runs a tad rich but all in all fine. Until WOT after a few seconds of being in it the truck goes nuts, misfire on all cylinders, gas petal does nothing but the motors still running... I think. After about a minute the petal came back. ***************


Fast forword to today. Did it again but this time the battery light is flashing, battery is not charging, no oil pressure. Im freaking out, turn off the radio..... Tahoe is stalled. coasted off the interstate. thankfully it stalled a 1/2 mile from my exit. fired right back up when I turned the key.
Oil and trans fluid levels are fine. new plugs, wires, fuel filter, and pcv valve.

 

Sounds like your tuner didn't set your tune correctly. Either throwing too much fuel at it or not enough.

Oh, check fuel pressure too, just because the filter is new doesn't mean it's not restricted somehow (or the pump is dying).

 

When i was looking at the tune i saw that the commanded a/f was 14.1 instead of 14.7. Enough to be too much?

 

I'll check the fuel pressure on my next day off

 

14.1 would account for ethanol in the fuel.

 

Almost sounds like a map or maf issue, hard to tell without seeing the data though..