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Old 09-17-2012, 09:55 AM   #13
miker92
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Join Date: Mar 2009
Location: Saratoga Springs, NY
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Quote:
Originally Posted by Cm452 View Post
How do you know it is lean? I'd check if the wastegate is getting jammed. Sometimes when they get really hot they get sticky, that is, the actual flapper has binding points in the housing. Perhaps the the duty cycle of the BPC is too high? Do you have a BOV? I know T7 should NOT have one, but some people have 'em.
I call BS on lean, and if instruments tell you otherwise they are prolly wrong. Ya see, a tiny turbo moving tons of air outside its pressure-flow efficiency realm is going to be pumping heat--massively. Yes, the ETS is good, but, for all that back pressure on the choked Td04 #5, you are going to get soaring EGT's as well. If it were *actually* lean you'd have A) The ECU pulling boost, dumping fuel, and killing timing. B) A toasted engine.
You'd notice if the ECU intervened, which means that it is probably not knocking and thus not lean.
I'd wager it is something mechanical or something to do with the software not meeting requests somewhere else and compensating by over-cycling the BPC. Since JZW is a tuning demigod, I'd imagine it is the former.
Experiment: Unplug the BPC and do your pulls.If you notice boost increasing this means that your WG is sticking. If not we'll try something else.
-Cm
When it hits higher boost levels, it stutters and doesn't accelerate smoothly. It's as if the engine is gagging. Sometimes, but not always, boost drops off almost instantly from ~26psi to about 15psi. If it stays at the higher level, the revving of the engine sounds strained. It's hard to describe, but it's sort of higher pitched and quieter, not as throaty sounding. When it boosts really super high, like 28 or so, the entire car bucks in what essentially feels like a violent misfire. This stuff, combined with the idea that my fuel system, which is stock except for the 3.5 bar FPR, can't possibly supply enough fuel to balance out that much air flow, is why I thought it would be running super lean under high boost.
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