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1G fuel cut / detonation? at 5500 rpm and up

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boosthead

10+ Year Contributor
35
0
Dec 13, 2009
greenfield, Wisconsin
Hey everyone im new to the forum, i just picked up my first dsm!
its a 90 tsi awd

anyways, ive been driving it around and in all gears besided 1st, when reaching 5500 rpm under boost, it feels like it all of a sudden looses power/jerks a bit.
otherwise 1st gear feels fine.

it has a 3 inch o2 housing back, test pipe
turbo xs mbc set at lowest setting
and hks ssqv bov, vented(this might be the problem)

thanks in advance
jon
 
First thing I'm going to say is check for boost leaks. If that checks out, take a look at your spark plugs and boot. Do you have a CEL?
 
Well 5500 is the sudden peak in the timing curve of the 1g ECU. Are you running premium gas? Check for boost leaks and try to get that BOV recirced. What boost level are you at? You say the lowest setting.

Are you sure you understand how a MBC works?

The looser the screw the less tension on the spring which will lower the boost. the tighter the screw the more boost.
 
ok guys thanks for the help

No CELs pop up, so idk if that's good thing or bad thing
My MBC is set all the way negative?

I'll check for boost leaks and haven't filled it up since I got it
so I will put premium in it. I'll also look at the spark plugs and boot and wires.

And another thing I just went out and cranked the MBC the opposite way and the car started doing the same thing at 4000 rpm in all gears.

hope that helps
thanks
jon
 
and another thing i just went out and cranked the mbc the opposite way and the car started doing the same thing at 4000 rpm in all gears

Try hooking up the vacuum hose from your wastegate actuator directly to your compressor housing with the MBC out of the car. If your car stops jerking then it could be a faulty MBC. However, I highly doubt it's the MBC that's causing this. You're probably getting multiple misfires. Just check for boost leaks and spark plugs/boots and let us know.

Here's a picture of what I mean by hooking up the hose directly from the wastegate actuator to your compressor housing.
 

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Try hooking up the vacuum hose from your wastegate actuator directly to your compressor housing with the MBC out of the car. If your car stops jerking then it could be a faulty MBC. However, I highly doubt it's the MBC that's causing this. You're probably getting multiple misfires. Just check for boost leaks and spark plugs/boots and let us know.


OK im going to go out and try that

and also it doesn't seem to me that the waste gate is actuating? when u rev in under the hood, should u be able to see the waste gate arm move? because its not

premium fuel didnt seem to help either

oh and another thing, with a mbc hooked up, are you supposed to just let the boost solenoid just sitting there or what?
 
im having the same exact problem with my 91 tsi. and now its left me stuck again driving my 84 blazer mud truck as a dd :/ if you find out the prob let me know. and i have already tried taking my boost controller off and hooking just a vaccume line from waste gate to the compressor housing, and it didnt work.... well atleast for me. but i think i may just be running rich with a walbro 255 and stock injectors and stock fpr? i do have a vented bov if that makes a difference?
 
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