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Discussion Starter · #1 ·
1987 Grande National, having trouble with power. When full throttle, engine loads up and loses performance, and badly hesitates. When throttle is at 7 pounds boost it is okay. Anything above that there is the problems. It feels like loss of fuel pressure, but have checked it out and there is lots of fuel pressure there. Please advise if you have had any similar issues.
 

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Fuhgeddaboudit
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Sounds like severe knock and the chip is pulling out timing. How much boost at WOT?

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ED BAKER
87-T-TYPE, PT54,MSD50's,Crane Billet Roller,JE forged20over,P&P Heads,Manley valves,Hemco 65mm& Acu65TB,V2 FM, P.I.9.5 -7disc,Jimmys Trans, new times soon.
93 PARK AVE"SUPERCHARGED"
67RS/SS350 CAMARO
mailto:[email protected][email protected]</A>
http://www.modernmusclecar.net
 

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How much is lotsa fuel pressure? Are you getting increased FP at WOT? Do you still have the cat on it?
 

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SCONE WIZARD...
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Is this 15 PSI boost on an aftermarket guage?

The stock one is not 100% accurate and pegs out at 15 PSI.. If you were using the stock one, and its pegged when you floor it, I would check the little Y shaped vacuum lines that go from the turbos compressor to the wastegate diaphram.. Chances are, if you have never done them, they are rotted, and leaking or broke.. in which case the 15 PSI you are seeing on the stock boost guage might be ALOT more, and the car is laying down due to severe over boost...b/c the boost press is not getting into the wastegate diaphram [bad hoses]to open it up and control boost..

Just throwing this out there incase


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DTA... don't trust anybody...
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1987 Turbo Limited--> Sold Nov 2001
 

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Discussion Starter · #8 ·
Originally posted by Schlodes:
Is this 15 PSI boost on an aftermarket guage?

The stock one is not 100% accurate and pegs out at 15 PSI.. If you were using the stock one, and its pegged when you floor it, I would check the little Y shaped vacuum lines that go from the turbos compressor to the wastegate diaphram.. Chances are, if you have never done them, they are rotted, and leaking or broke.. in which case the 15 PSI you are seeing on the stock boost guage might be ALOT more, and the car is laying down due to severe over boost...b/c the boost press is not getting into the wastegate diaphram [bad hoses]to open it up and control boost..

Just throwing this out there incase


y shaped lines are new, using ariginal boost gauge. While its acting up it is surging also
 

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Fuhgeddaboudit
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Time for a new aftermarket boost gauge. Also there has been some defective "Y" hose setups going around. Turn the boost down until the factory gauge has space space on the end 10-12 lbs boost. Do this so your head gasket stays in one piece.

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ED BAKER
87-T-TYPE, PT54,MSD50's,Crane Billet Roller,JE forged20over,P&P Heads,Manley valves,Hemco 65mm& Acu65TB,V2 FM, P.I.9.5 -7disc,Jimmys Trans, new times soon.
93 PARK AVE"SUPERCHARGED"
67RS/SS350 CAMARO
mailto:[email protected][email protected]</A>
http://www.modernmusclecar.net
 
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