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Old 12-01-2005, 09:45 PM   #11
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nah, I'm chasing a different monkey I was hoping was related to the map. Discussing it got me in this thread so I figured I'd post the book info to see if it was any help.

Appears the problem couldn't be lean/rich related because not only does the PCM not listen to the o2 sensor at WOT, thus it has no idea if it'* rich or lean, but that'* not used in determining load anyway, which by the book is the reason it would be dumping boost.

As funny as our throttle position sensors can be (and as much as people like tinkering with them), that'* probably the first place I'd look. A high TPS reading with low RPM may make the PCM think it'* under a heavy load. That situation seems to have the makings of a boost dump.

If you use your imagination a little that could also explain a bit of why changing the fuel changed the boost dump. If you were adding too much or too little fuel then you may not have been making peak power. Correcting it may have given you a few extra ponies that helped keep the RPMs more inline with the TPS sensor which would change the load reading and maybe just enough to keep it from dumping boost.

There are a few problems on the surface of that thought, but maybe something to look into. Those of you with that problem might try adjusting the TPS down a little to see if it has any effect.
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Old 12-01-2005, 10:36 PM   #12
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DrJay you might be onto something their... I have had problems with the TPS and a high voltage code. I didn't think much of it since it wouldn't light up all the time and just figured that I'd fix it over the winter. Maybe that will kill two birds with one stone.
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Old 12-01-2005, 10:55 PM   #13
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Hang on, I've optimized my TPS just like the article posted in Techinfo, and I have no overboost, but then again, the Jet is supposed to delete that protection.

But then again, Doc, aren't you still running the Jet?
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Old 12-02-2005, 12:10 AM   #14
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Yeah I'm still using the jet chip but jet would have to be pretty in tune with the 3800 to know to disable boost control. Plus that would be a HUGE liability on their end. I doubt a giant like Jet would like lawsuits because they disabled some factory engine protection especially since it'* mainly used in reverse. I would see that inline with something like disabling the knock sensor. I have no idea though, maybe they did.

It doesn't seem like a wildly widespread problem so it may just be with a few people that overadjusted their TPS and/or chock it up to differences in engines. Plus, as was used in the example above, you have a bit more power than many. That may be helping you keep your RPM up along with the TPS so when the total load is worked out, you're on a different playing field and within the limits.

The thought there is if you could make your RPM'* climb at the exact same rate as your TPS your engine is basically under no real load (like revving in neutral) and according to the manual that would stop boost dump.

Like I said there'* a few problems with the thought we can certainly come up with but the quick way to check would just be to lower the tps readings a bit and see if it has any effect. Probably take like 10min to change and check anyway.

just a thought...
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Old 12-02-2005, 12:13 AM   #15
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Okay, you're putting down more power than I am. What issues are you having?
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Old 12-02-2005, 12:19 AM   #16
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Tearing my transmission to pieces, trouble driving in the rain, pesky ricers, a goofy PCM and maybe something funny with my new MAP...other than that not much.
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