KB vacuum
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Elder User
Joined: May 2007
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KB vacuum
When my truck is at a stop in drive it only pulls 18in hg but in park it pulls 20ingh
Also it runs lean 16afr right when i press the gas under normal driveing for a second then goes to 14.7(normal) dono if i have a vacuum leak or what. Could it be the cold weather?
Also think it could be my PVC valve, there is oil around the gormit and top of the hose. Any help would be great (my AFR gauge is a wide band auto meter and my vacume is a mecanical auto meter so i know that the are right on if not perfect)
Also it runs lean 16afr right when i press the gas under normal driveing for a second then goes to 14.7(normal) dono if i have a vacuum leak or what. Could it be the cold weather?
Also think it could be my PVC valve, there is oil around the gormit and top of the hose. Any help would be great (my AFR gauge is a wide band auto meter and my vacume is a mecanical auto meter so i know that the are right on if not perfect)
Laughing Gas
Joined: Dec 2007
Posts: 959
Likes: 8
From: Imperial, MO
The vacuum sounds about right. You will see a little less vacuum in gear at idle than you will in park at idle due to the difference in rpm.
The A/F ratio deal sounds like it's probably an issue in the tune. What happens at WOT?
-Rod
The A/F ratio deal sounds like it's probably an issue in the tune. What happens at WOT?
-Rod
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03 F350 v10 Kb supercharger, 36lb injectors, Kb boost a pump,Kb switch chip, heat range cooler ngk plugs gaped to 35, no cats, one of those y pipes off ebay, flow master 40 series muffler, and i think that's about it. at wide open it goes right to 10.2 afr at 6 psi and fuel pressure is like 44 to 45 psi, so it fricken rich, when i look out my mirror i can seen a wight cloud of smoke. thanks for the input
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From: Calhoun GA
It sounds like you're experiencing a tip-in-lean condition, when the A/F ratios go lean after the throttle is pressed.
11.5 is a good number to shoot for for a boosted application. A tuning change can correct both issues.
11.5 is a good number to shoot for for a boosted application. A tuning change can correct both issues.
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From: Calhoun GA
I agree with Fred.
I build my programs off a 11.6 A/F ratio with 93 octane and then raise the timing a degree or two at a time (on a dyno). The power gains will keep increasing until you hit a "buffer zone". This is where the motor wont make any more power with added timing. At that point, backing the timing off a degree or two will keep things safe.
Another variable to consider is air charge temps (ACT). The ECU can be programmed to pull timing and/or add fuel when the ACT's get too excessive.
I build my programs off a 11.6 A/F ratio with 93 octane and then raise the timing a degree or two at a time (on a dyno). The power gains will keep increasing until you hit a "buffer zone". This is where the motor wont make any more power with added timing. At that point, backing the timing off a degree or two will keep things safe.
Another variable to consider is air charge temps (ACT). The ECU can be programmed to pull timing and/or add fuel when the ACT's get too excessive.