LT1 fuel split
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From: LT1 land...the "409" of the 90s!
The individual cylinder fuel adjustment table is there '94 thru '97. If your software lists the cylinders as 1,2,3,4,etc, they follow the firing order, I re-numbered mine as 1,8,4,3,6,5,7,2 so I could stop counting on my fingers.
If everything is mechanically sound, the needed adjustments should not have to be very big. I don't remember seeing your fuel trims.
If you have an infrared temp gun (most auto techs have them) you might shoot the headers near the heads to look for a problem cylinder. On the lean/high fuel trim side you want to add more fuel to the hottest cylinders instead same to all four. If you find a cold header tube on the high fuel trim side, suspect incomplete combustion. That puts more oxygen out the exhaust port. The O2 then sees more oxygen and the dumb-assed PCM thinks that always means lean, so trims go up and it throws more fuel at it.
If you pulled plugs and looked for dark plugs on the high trims side I must have missed it.
Good luck.
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From: Little Rock, Ar
Have you re-checked to make sure the new gasket sealed it up? If you open the throttle to something like 1500 RPM, is the fuel trim split the same?
The individual cylinder fuel adjustment table is there '94 thru '97. If your software lists the cylinders as 1,2,3,4,etc, they follow the firing order, I re-numbered mine as 1,8,4,3,6,5,7,2 so I could stop counting on my fingers.
If everything is mechanically sound, the needed adjustments should not have to be very big. I don't remember seeing your fuel trims.
If you have an infrared temp gun (most auto techs have them) you might shoot the headers near the heads to look for a problem cylinder. On the lean/high fuel trim side you want to add more fuel to the hottest cylinders instead same to all four. If you find a cold header tube on the high fuel trim side, suspect incomplete combustion. That puts more oxygen out the exhaust port. The O2 then sees more oxygen and the dumb-assed PCM thinks that always means lean, so trims go up and it throws more fuel at it.
If you pulled plugs and looked for dark plugs on the high trims side I must have missed it.
Good luck.
The individual cylinder fuel adjustment table is there '94 thru '97. If your software lists the cylinders as 1,2,3,4,etc, they follow the firing order, I re-numbered mine as 1,8,4,3,6,5,7,2 so I could stop counting on my fingers.
If everything is mechanically sound, the needed adjustments should not have to be very big. I don't remember seeing your fuel trims.
If you have an infrared temp gun (most auto techs have them) you might shoot the headers near the heads to look for a problem cylinder. On the lean/high fuel trim side you want to add more fuel to the hottest cylinders instead same to all four. If you find a cold header tube on the high fuel trim side, suspect incomplete combustion. That puts more oxygen out the exhaust port. The O2 then sees more oxygen and the dumb-assed PCM thinks that always means lean, so trims go up and it throws more fuel at it.
If you pulled plugs and looked for dark plugs on the high trims side I must have missed it.
Good luck.
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From: Little Rock, Ar
I've done the IAC passage BS and it didnt change a bit. It does however idle on its own with the TB almost completely close
I would check for cold header tubes, extremely hot header tubes, also swap sides with the injectors.
What kind of headers, and which side appears lean?
And, why won't you post your fuel trims?
What kind of headers, and which side appears lean?
And, why won't you post your fuel trims?
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From: Little Rock, Ar
I don't have fuel trims on a laptop. My tuner explained my problem and so I've been resorting to my Interceptor gauge. It's a simple gauge but clearly explains weather B1 & B2 are close or split.
0.0 is even.
B1 reads +49.9(max)
B2 reads -17.x to -24.x
I've been trying to get ahold of an infrared gun but no luck.
A few mins ago I was monitoring my garage, and took some carb cleaner to each indivual Header primary, and while I was spraying on the primary, B1's +49.9 would start to drop drastically, then back up as soon as I stopped. I moved on the the next primary & and the next, with the same results.
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From: Little Rock, Ar
Update:
I installed my facotory TB on it and the fuel split went from:
B1 +49.9(max on gauage)
B2 -17.x to -24.x
After stock TB:
B1 +49.9
B2 +32.x(cold) +5.x to +15.x(warm)
So I've still got a split, but it isn't a lean/rich split. Just Lean/not as lean lol
That split could very well lessen when your tuner adds some fuel. The rear cylinders had the black plugs. Those holes are way rich if there are no ignition problems. What kind of spark plugs? What brand injectors?
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From: Little Rock, Ar
Delhi/MSD 55lbs injectors.
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From: Little Rock, Ar
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iTrader: (7)
Joined: Oct 2007
Posts: 1,177
Likes: 1
From: Little Rock, Ar