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Originally Posted by SinCityFX4
Ok, this is hard to expalin but here we go. The tranny does like these new tunes. The 1-2 shift rarely feels smooth and almost seems to bind up sometimes. Sometimes under light throttle it almost feels like the engine is bogging down but the RPM's are not altered. It is very wierd. THe other day it did it on the highway so bad I thought I had a flat tire and I had to pull out of traffic. Thats how rough it was. But the RPM's were fine staying around 1800.
I flashed it back to stock and drove 2 tanks through it and no problems. I flashed the 87 perf tune back in and 2 days later it started again. THe tranny issues are always there for some reason, but the engine/tranny stutter is not cool.
No DTC's, safe mode, or any form of error signals.....
At a loss here....
A side note the other am when I was leaving the house 1st thing it backfired up front. Sounded like it came from the intake but I was half awake and could not really tell.
Need some help on this one guys...gonna flash back to my VMP tune until I can get this resolved...
Perf wise my Mods are AFE CAI, SIDO Super 40's, Livewire (VMP-Troyer/Gryphon (PHP) depending on whose tune I am running.
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I'm probably not going to be a huge help on this, but I will throw in my $.02.
The backfire you describe can be one of two things.
1. Lean condition. The mixture is lean enough that it's burning slowly and still "on fire" when the intake valve opens again. It's common in a carbureted vehicle to exhibit this same condition when overly rich as well since the extra fuel will pool up (become a liquid again) and cause a lean condition. Since it's hard to get THAT rich with an EFI vehicle unless the ECT sensor is open and giving a reading of -40 degrees...........
2. Exhaust valve not opening. I doubt this is the case since you don't have any other engine related problems.
Your transmission issue really sounds like a shift timing problem, but it's difficult to get the PCM to command 2 gears at once without it knowing about it.