Running A/F < 10 . . . Build Boost Or Not?
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TECH Resident
Joined: Jan 2002
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From: Phoenix, AZ
Running A/F < 10 . . . Build Boost Or Not? I had just recently upgraded my fuel system so that it doesn't drop FP above 5Krpm. We had tuned the car to be dumping in LOTS of fuel before the fix. Now of course with my FP fixed, it's running extremely rich until I get it tuned again. What I've now noticed is that it won't build boost past 11psi, before it had no problem. I know my A/F is well below 10. From what I understand running too rich will cause your EGT's to drop, I'm thinking that could cause the turbo to stop building boost. Sound like a reasonable explanation?
I DO think I have a bad seal in the turbo; it blows blue smoke on decel, but only when cold. Once 10 minutes goes by I see no smoke at all. Could a bad seal cause it to stop building boost?
- Dug
I DO think I have a bad seal in the turbo; it blows blue smoke on decel, but only when cold. Once 10 minutes goes by I see no smoke at all. Could a bad seal cause it to stop building boost?
- Dug
Thread Starter
TECH Resident
Joined: Jan 2002
Posts: 956
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From: Phoenix, AZ
Yea, the smoking issue and my not building boost are two separate issues . . . the smoking has been going on for a while, the fuel system I just fixed, which makes me think the richness is causing it to stop @ 11psi.
- Dug
- Dug
My af is at 10.0 atm and i have no issue waht so ever with building boost. Builds full boost at 3k. I know that u are richer then that BUT i dont think it would have the effect u describe. I have a DSM as well and even wen the car is running like absolute *** it builds allt eh boost i want it to. I had the timing belt off 3 teeth which equates to about 30 degrees adn ti built boost fine but it was REALLY slow acceleration.
You say that its blowin smoke on decel. Do u stull have the PCV system hooked up? If not and its the turbo blowing it then maybe the turbo is screwed and it is the reason its not makin more boost. Can u hear the turbo over ur car? If so does it make and noises that dont sound good? GL man
John
You say that its blowin smoke on decel. Do u stull have the PCV system hooked up? If not and its the turbo blowing it then maybe the turbo is screwed and it is the reason its not makin more boost. Can u hear the turbo over ur car? If so does it make and noises that dont sound good? GL man
John
Thread Starter
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Joined: Jan 2002
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From: Phoenix, AZ
Hey thanks John . . . my AF drops below 10 @ 3600rpm and never appears again. I actually threw it on the dyno ( I happened to be there, but no tuner ) and you can see on the dyno the curve starts dipping down as the AF goes richer.
I've got a checkvalve right in front of the TB where the line goes in, and I've got a breather cap on the valve cover . . . can't hear the turbo over the car ( never have ) and it's not making any funny noises. It's just weird because I dynoed about 2 months ago, had no problem hitting 12+psi. Revamped the fuel system and now it stops @ 11.
- Dug
I've got a checkvalve right in front of the TB where the line goes in, and I've got a breather cap on the valve cover . . . can't hear the turbo over the car ( never have ) and it's not making any funny noises. It's just weird because I dynoed about 2 months ago, had no problem hitting 12+psi. Revamped the fuel system and now it stops @ 11.
- Dug
