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420A Building boost at idle?

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Inkdlyfe

Inkdlyfe

Proven Member
438
7
Feb 23, 2016
Summer feild, Florida
So recently my car been building less and less boost and now im building about 7 psi of boost not even reving or even idling high ... just at a normal stand still im building boost. I have my wg set at 28 lbs which i was running fine but now. Its like im running a boosted car with out the ic pipe connected to the TB or some thing. My wide band im sure went out only reads --- now so I can't even get a reading off that. But im building 7 psi at idle and only hitting maybe 11 psi at wot. Unlike before 0 psi at idle and 28 some time over boosting to 32 psi.. i can't find any boost leaks my wg is tight no leaks or exhaust leaks... my boost gauge is T from the fpr also. And I have no visible leaks. Another thing I noticed I think im dumping way too much gas too :/ i have new spark plugs and they are all evenly gapped at .028.
 
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Check Your vacuum line to the bov hat. Your bov should lift at idle due being under vacuum at idle speeds. Maybe the bov isn't opening at idle. But ive also never experienced your condition before. As for low boost numbers check to see if the manifold to turbo gasket isn't damaged or leaking it will hiss really bad when you hit the peak boost.
 
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Ill look into all the gaskets next but I did recently adjust the bov imma adjust that back
 
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Sounds like a plan. Let me know what you find out. Look for black carbon blow out around the manifold to motor gasket and the manifold to turbo gasket. It will be very easy to see.
 
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jed344 said:
You are not making boost at idle I assure you. Your gauge is not reading accurately. I cant think of any turbo motor ever created that will make positive pressure at idle.
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Me neither I've fixed tons of turbo cars clients and friends, and never ran into this but i didn't want to label it impossible. I have to side you about the gauge.
****does the motor feel slower than usual or does it read lower and feel the same as usual?
 
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I believe I stated this in a prior thread of yours where something similar was questioned...but you cannot build boost at idle where there is no load on the engine and the throttle plate is 100% closed. Any time the throttle plate is closed there is a vacuum condition inside the intake manifold, so building boost is impossible.
 
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It's possible to have boost at low RPM with space-age wizardry, but the average car absolutely cannot build boost at idle, unless the turbocharger is hilariously undersized for the application (think 454 with a 14B or something). You're doing something wrong.

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I would say that you have 7 inches of vacuum, not boost, which would mean that you have a vacuum leak somewhere or your timing is off either of which would make it run poorly
 
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Ok changes so much stuff around and yeah still got boost at idle as the gauge says :/.. imma order a new gauge. Where is a good place to tap into ? Mine is from the back of the intake then T off to the bov and then into the boost gauge. Is that a good place or ?
 
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GM flow sensor ?
And so that means I should just run my boost gauge by its self to the intake ?
What about that single vacc port right on the throttle body ? I currently have that just capped off nothing goes to it .
 
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