Think I Found out what my Lean Problem was...
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Joined: Sep 2002
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From: All over the US
Originally posted by Nasty Wendy
If the vacuum line is pulled off or came off of the regulator the truck would run rich up until the motor was operating at 0 vacuum. At 0 vacuum it would run stoich and under boost it would run lean. The vacuum line reduces the back pressure the regulator gives when the motor is running under vacuum. And it incrreases the backpressure the regulator gives when the motor is running under boost. This keeps the fuel pressure in the rails at a constant margin above the intake manifold pressure.
If the vacuum line is pulled off or came off of the regulator the truck would run rich up until the motor was operating at 0 vacuum. At 0 vacuum it would run stoich and under boost it would run lean. The vacuum line reduces the back pressure the regulator gives when the motor is running under vacuum. And it incrreases the backpressure the regulator gives when the motor is running under boost. This keeps the fuel pressure in the rails at a constant margin above the intake manifold pressure.
When you put your foot down on the accelerator and open the throttle blades, vacumm in the motor is decreased and the diaphram in the regulator allows less fuel to return to the tank so that the rail has plenty of fuel for tip in acceleration or WOT. The computer commands IPW (injector pulse width) and will do so to reach its A/F goals, but if a vacuum line comes off or is broken, the computer can still maintain fuel control even though fuel rail pressure has increased somewhat. you wont go RICH just because the line came off, but your computer will have to adjust fuel trim.
If the regulator goes bad, meaning the diaphram pops, it can leak fuel into the vacuum line directly into the engine and hydralic the engine, Ive seen this many times on older Ford vans. Sometimes the diaphram spring breaks and the regulator doesnt allow any fuel to go back to the tank and rail pressures are increased by as much as 1 1/2 the normal fuel pressure. Its called "deadheading".
Hope this helps.
****, whoooops, I mean
ROCK ON
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Joined: Jun 2002
Posts: 745
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From: Waggaman Louisiana
Originally posted by Grey03
I think I know what your trying to say, but I dont think you understand how it works.
When you put your foot down on the accelerator and open the throttle blades, vacumm in the motor is decreased and the diaphram in the regulator allows less fuel to return to the tank so that the rail has plenty of fuel for tip in acceleration or WOT. The computer commands IPW (injector pulse width) and will do so to reach its A/F goals, but if a vacuum line comes off or is broken, the computer can still maintain fuel control even though fuel rail pressure has increased somewhat. you wont go RICH just because the line came off, but your computer will have to adjust fuel trim.
If the regulator goes bad, meaning the diaphram pops, it can leak fuel into the vacuum line directly into the engine and hydralic the engine, Ive seen this many times on older Ford vans. Sometimes the diaphram spring breaks and the regulator doesnt allow any fuel to go back to the tank and rail pressures are increased by as much as 1 1/2 the normal fuel pressure. Its called "deadheading".
Hope this helps.
****, whoooops, I mean
ROCK ON
I think I know what your trying to say, but I dont think you understand how it works.
When you put your foot down on the accelerator and open the throttle blades, vacumm in the motor is decreased and the diaphram in the regulator allows less fuel to return to the tank so that the rail has plenty of fuel for tip in acceleration or WOT. The computer commands IPW (injector pulse width) and will do so to reach its A/F goals, but if a vacuum line comes off or is broken, the computer can still maintain fuel control even though fuel rail pressure has increased somewhat. you wont go RICH just because the line came off, but your computer will have to adjust fuel trim.
If the regulator goes bad, meaning the diaphram pops, it can leak fuel into the vacuum line directly into the engine and hydralic the engine, Ive seen this many times on older Ford vans. Sometimes the diaphram spring breaks and the regulator doesnt allow any fuel to go back to the tank and rail pressures are increased by as much as 1 1/2 the normal fuel pressure. Its called "deadheading".
Hope this helps.
****, whoooops, I mean
ROCK ON
If you've ever tuned a GN you'd have a better understanding of FPRs and IPWs in boosted engines than most.
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Joined: Sep 2002
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From: All over the US
Just giving you different ways the FPR can go bad, I'm not saying this is his problem.
Your talking about going way lean with a small vacuum leak, that is where this was going, but your not going to go way lean with just a tiny vacuum leak nor is a disconnected FPR going to cause a lean condition, thats what this is about.
Have you ever looked into adjustable FPR's for Lightnings? I know of someone claiming actual HP gains by just adjusting the FP up 2lbs from stock.
his theory is sound, but he is way off base.
GOT MILK
Your talking about going way lean with a small vacuum leak, that is where this was going, but your not going to go way lean with just a tiny vacuum leak nor is a disconnected FPR going to cause a lean condition, thats what this is about.
Have you ever looked into adjustable FPR's for Lightnings? I know of someone claiming actual HP gains by just adjusting the FP up 2lbs from stock.
his theory is sound, but he is way off base.GOT MILK
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Joined: Sep 2002
Posts: 803
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From: Belleville, MI
well, i still cant get ahold of anyone over at livernois to see what the hell is going on, i spoke w/ someone yesterday (thurs) and he said it should be done afternoon, but nobody ever called me, so im trying to get ahold of someone today, because lean or not, i dont want them to have my truck for the weekend....