Running too Rich
Thread Starter
Junior Member
Joined: Sep 2000
Posts: 37
Likes: 0
From: Gibsonia, PA U.S.A.
Running too Rich
How do you adjust the mixture on a q-jet?
iafter i installed the K&N air dropbase air cleaner, a 1" spacer, and replaced my cat with a peice of pipe, my mpg dropped from about 12-13 to about 3-4. is the mixture screw in the front, bottom right?
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1987 Trans Am
Black & Gold
Light Mods
iafter i installed the K&N air dropbase air cleaner, a 1" spacer, and replaced my cat with a peice of pipe, my mpg dropped from about 12-13 to about 3-4. is the mixture screw in the front, bottom right?
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1987 Trans Am
Black & Gold
Light Mods
Supreme Member
Joined: Sep 1999
Posts: 7,072
Likes: 13
From: Philly, PA
It's not adjustable. The ECM contolls the idle, part throttle and mid-range mixtures. Only WOT is changable by normal means (swapping jets/rods). The idle screws you are looking at only affect curb idle and have limiter caps on them so they don't have hardly any adjustment range to them at all. THe one on the front bottom right is the curb idle speed screw, not a mixture screw.
Somewhere in your upgrades you hosed something up. That's a MASSIVE decrease in mileage. Did you disconnect the M/C solenoid plug accidentally (the big blue two-wore plug on the top of the carb)? Did you take off or oytherwise molest anything else while you were doing the mods? There is NO WAY that these mild mods threw your tuning off that much. SOMETHING else is screwy here.
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94 Firebird Formula M6- No options but Z rated tires. No mods over $10. 13.5@105.
79 Malibu "beater" w/junkyard 400 SBC, tweaked QJet 4bbl, finally a decent set of heads, a few other tricks. A maddening 13.000001 @ 108 on the motor with little traction. No nitrous runs with the new heads yet.
Grandma's old 78 Malibu (33K miles!) soon to have the powertrain from the 79 put in it.
"One of the last remaining QJet tuners on Planet Earth!"
Somewhere in your upgrades you hosed something up. That's a MASSIVE decrease in mileage. Did you disconnect the M/C solenoid plug accidentally (the big blue two-wore plug on the top of the carb)? Did you take off or oytherwise molest anything else while you were doing the mods? There is NO WAY that these mild mods threw your tuning off that much. SOMETHING else is screwy here.
------------------
94 Firebird Formula M6- No options but Z rated tires. No mods over $10. 13.5@105.
79 Malibu "beater" w/junkyard 400 SBC, tweaked QJet 4bbl, finally a decent set of heads, a few other tricks. A maddening 13.000001 @ 108 on the motor with little traction. No nitrous runs with the new heads yet.
Grandma's old 78 Malibu (33K miles!) soon to have the powertrain from the 79 put in it.
"One of the last remaining QJet tuners on Planet Earth!"
Thread Starter
Junior Member
Joined: Sep 2000
Posts: 37
Likes: 0
From: Gibsonia, PA U.S.A.
I checked all the ele. connectors, and checked all of the other things attached to the carb. the only thing that id disconnected it the vacuum hose for the hot air stove(i don't have one), but i have that capped off. i don't know what it is.
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1987 Trans Am
Black & Gold
Light Mods
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1987 Trans Am
Black & Gold
Light Mods
Thread Starter
Junior Member
Joined: Sep 2000
Posts: 37
Likes: 0
From: Gibsonia, PA U.S.A.
should i maybe plug the pipe that comes from the AIR pump? i'm going to pull the plug on the computer power to reset the codes, too. maybe it will fix it's self?!?
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1987 Trans Am
Black & Gold
Light Mods
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1987 Trans Am
Black & Gold
Light Mods
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