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Abnormal? turbo guage reading? 700 1989

posted by sgtsalamander on Fri Sep 3 01:39 CST 2004
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last visit: Sat Nov 21 05:03 CST 2009

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Hi guys,

I've looked through the other threads, and I can't find an exact answer to my question, and I'm sure someone has a good answer but I'm just not looking in the right place.

I recently got my Air Mass Meter replaced, and now the turbo guage will go WAY into the boost area of my guage. The turbo does provide boost, but there is a small black cloud of smoke when I near the end of the turbo guage. I am used to turbos only going halfway and then having the boost kick in. I'm wondering if/what the problem is.

Oh, and also, the boost provided doesn't seem to have the usual delayed "kick" that turbos are noted for.

Any more details needed, please ask, and thanks in advance for all the advice.

--
1991 744T 415 000KM sold Sept 2003, Presently: 1989 744T 160000Km

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Abnormal? turbo guage reading? 700 1989

posted by the kick inside on Tue Sep 7 12:08 CST 2004
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last visit: Thu May 17 09:58 CST 2007

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if the guage is going WAY further than it used too...and thats past about 2am on my factory guage (verified by a calibrated guage) then you have overboost...

verify by fitting a calibrated guage...

overboost (uncontrolled) can severely damage your engine (like replacement time!)

the other possibilty is a guage going U/S..but i doubt that..i mean i really doubt it...

try fitting a calibrated vacume/boost guage (hint u can pick up REALLY cheap ones sold for carb balancing that are generally actually better than the 'boost' guages sold in acessory shops) then u just need to rig a mount for it...t it into the boost guage line in the dash...abotu 10 minute job...

cant say i have ever noticed much of a delay in my boost, its pretty smooth and controlled...though you certainly know when its arrived, but then again i am runnign a mildly moded air intake and exhaust and a manual box...im guessing im up around 200bhp under full boost...

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Abnormal? turbo guage reading? 700 1989

posted by the kick inside on Fri Sep 3 08:43 CST 2004
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last visit: Thu May 17 09:58 CST 2007

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does the car now go like a bat out of hell when in boost ? (guesing it does...)

if so then when replacing the AMM someone either disconected the vacume tube to the waste gate, or the waste gat actuator...meaning the wastee gate doesnt now open so you are running overboost...

in theory eventualy (up around 15psi i believe) the engine will stumble as the fuel shut off switch kicks in to save the engine going BANG!...

the black smoke will probably be an overfuelling situation...

if this sounds correct to you i suggest its sorted ASAP as its not good for the engine....

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Abnormal? turbo guage reading? 700 1989

posted by sgtsalamander on Sat Sep 4 03:26 CST 2004
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last visit: Sat Nov 21 05:03 CST 2009

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Unfortunately, it doesn't really seem to overboost. Everything was great after the AMM replacement for about a week, but then I started having these problems.
--
1991 744T 415 000KM sold Sept 2003, Presently: 1989 744T 160000Km

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Abnormal? turbo guage reading? 700 1989

posted by KLR142 on Tue Sep 7 18:17 CST 2004
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last visit: Mon May 9 12:44 CST 2011

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Yeah, if it were overboosting, you'd be running lean most likely because of all the extra air being forced into the motor... There's got to be something up with your gauge, or something on the way to the gauge. Well, that's my guess anyway. So, for throttle feel, lets say you're around 2000 or 2500 rpms, and then you floor it, do you still feel a pause for a bit, and then a smooth and fast rush of power? If not, then you're having more problems... I wonder if a vacuum leak of some sort could cause this problem? Might not hurt checking, but anyway, good luck! Peace,
--
Kyle - attending Ore. State, while my lil '68 142 (256k, 74 b20, m40, iPd bars, other misc... =D) waits for its next outing...

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Abnormal? turbo guage reading? 700 1989

posted by sgtsalamander on Sat Sep 11 15:55 CST 2004
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last visit: Sat Nov 21 05:03 CST 2009

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Thanks so much for the advice. There is however, no pause before the boost.

Surprisingly enough, some hose checking (duh) fixed the problem. I don't have one of the manuals in front of me, but there is a small hose about the width of your little finger that runs vertically, near the turbo. It had snapped off at the connection. I got the old piece off, snugged the rest of the hose up, and clipped it back on. Turbo now "pins" as it should and the car is responding as normal.

Thanks again everyone.
--
1991 744T 415 000KM sold Sept 2003, Presently: 1989 744T 160000Km

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