My factory manuals (a total of five) all say to do the adjustment with the air cleaner off. Period.
3.8 dualjet part throttle hitch
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My factory manuals (a total of five) all say to do the adjustment with the air cleaner off. Period.
Its impossible to adjust the IAB valve with the lid on so it has to be temporary removed. However, when the lid is off the engine is running slightly lean which makes the computer run rich, throwing the adjustment off. So once you adjust it at 30 degrees with the lid off, and put the lid back on it will be slightly rich. Not to mention all the air turbulence and reduced pressure differential caused by a missing lid. Read about checking the dwell adjustment after replacing the lid and letting the computer to settle down in a 1986 GM service manual that covers G and B bodies. Most instructions neglect this step.
It's impossible to adjust the idle mixture screws with ANY part of the air cleaner installed. This is what I and the OP are supposed to do.
But which '86 service manual are you referring to? I'm never averse to new info. If you can, please post a scan or snapshot of the relevant page(s).
I certainly agree with the gist of what you're saying, I think about it every time I adjust the mixture. I've always just assumed that things were designed and calibrated taking that into account, so the adjustment would come out right with the air cleaner on after doing it with the air cleaner off. There's nothing says the dwell needs to be exactly centered with the air cleaner on. But I've also wondered if it wasn't a f-up on somebody's part. Lord knows the whole "feedback carburetor" idea was a f-up from beginning to end.
EDIT: Er, forgive me. I don't know what got into me.
But which '86 service manual are you referring to? I'm never averse to new info. If you can, please post a scan or snapshot of the relevant page(s).
I certainly agree with the gist of what you're saying, I think about it every time I adjust the mixture. I've always just assumed that things were designed and calibrated taking that into account, so the adjustment would come out right with the air cleaner on after doing it with the air cleaner off. There's nothing says the dwell needs to be exactly centered with the air cleaner on. But I've also wondered if it wasn't a f-up on somebody's part. Lord knows the whole "feedback carburetor" idea was a f-up from beginning to end.
EDIT: Er, forgive me. I don't know what got into me.
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I used to do transmission work. Often, a "hitch" like you describe can result from a leaky/sticking EGR valve, which could either be the valve itself, or something wrong with the EGR controls (solenoid, vacuum lines, etc.). Customers would bring their car in with this complaint, thinking transmission, when it would be something else. Another possibility is that the torque converter is staying locked up when it should unlock under those conditions. Might also check the MAP sensor vacuum hoses and sensor operation.
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