My 88 760 turbo is seems to be over busting then it buck when the turbo needle goes all the way to the bottom of the gage and cut back/shut off. If I put the car in neutral and rev the engine the turbo works fine. If I am driving and the RPM exceed 3K the turbo starts acting up. If I don’t let the turbo needle goes all the way to the bottom the car runs fine.
What could be the problem?

Please explain: Over Busting, turbo needle goes all the way to the bottom of the gage and cut back/shut off?


Which Bottom, the right hand side in the red? If so, check your wastegate contol valve hose, from the compressor to the WG. diaphram. It sounds like an overboost situation and the overboost sw is cutting the engine out. Replace the hose. Sever overboost can cause the engine to self destruct! (IE conn rods through the block!)

the far right bottom where the gage is all white. Where and what is the Wastegate control valve and compressor.I will try to find it and check it tonight when I get home.

I will let you know what I found.

On the front of the turbo is a hose barb with a black hose leading down and into the diaphram. If it's off, get a new piece of hose, 1/4", and replace it. Regular fuel line is fine. You do not want to over boost the engine due to the aforementioned engine self destruction.
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Warren Bain - '86 744Ti M46 >290Kmi, '99 V70Glt > 45K mi, '96 965 >100Kmi Wifemobile near Manassas Va.. Check the 700/900 FAQ via the 'features' pull down menu.

YOU ARE THE MAN! What you said was the exact problem. I fix it last night and everything is working fine now.


Thanks a million

OK, good. I'm glad it's working OK now.
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Warren Bain - '86 744Ti M46 >290Kmi, '99 V70Glt > 45K mi, '96 965 >100Kmi Wifemobile near Manassas Va.. Check the 700/900 FAQ via the 'features' pull down menu.

the little one that's hooked onto the main turbo air inlet pipe/hose in front of teh turbo via a small 90 degree coupling? vacuum hose that controls waste gate operation, right?

I never knew its name, but that tore once and eliminated the waste gate stop on my turbo... damned thing would fly into the red and the whole engine would cut out.

-rt

Hell be realy happy, mine was overboosting to a point i didnt notice and while on vacation one day i went to pass someone and sent her into passing gear and sent my Headgasket the other direction least i say i think it ended up on his windshield at least the thonking behind me lead me to believe that.

Sure is, any you're lucky.
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Warren Bain - '86 744Ti M46 >290Kmi, '99 V70Glt > 45K mi, '96 965 >100Kmi Wifemobile near Manassas Va.. Check the 700/900 FAQ via the 'features' pull down menu.