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I have an 88 supra, and whenever I start to build boost the engine feels like its gonna power down, but as soon as I let off the gas its ok and I can keep driving it. does anyone know what the problem could be? Thanks
 

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I have an 88 supra, and whenever I start to build boost the engine feels like its gonna power down, but as soon as I let off the gas its ok and I can keep driving it. does anyone know what the problem could be? Thanks
Check your intercooler piping.
 

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I'm having a boost problem as well. It doesn't seem to want to hold boost even at stock level. It was holding fine at first, the after the ProfecB ad break in it will peak at 8.1psi and fall to 4.0psi by 5000rpm. not sure what's going on. Can't find any leaks in the IC piping, and all vacuum hoses are firmly connected. It's holding steady vacuum, no problem, and builds boost just fine but won't hold it. I'm still on stock exhaust with a list of mods. Exhaust hasn't come in yet. i know that with higher boost the pressure will limit exactly how much it can hold, but at stock levels it should be fine. I've tried adjusting the gain as recommended by the ProfecB manual and still nothing. It only changes boost response, not the dropping off. Anyone have experience with this?
 

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have either of you actually pressurized your pipes with an adapter and an adjustable aircompressor to find out if u really have leaks? Just lookin at the pipes and tuggin on them is not enough need to test it properly.

You both might be in need of turbos though.
 

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have either of you actually pressurized your pipes with an adapter and an adjustable aircompressor to find out if u really have leaks? Just lookin at the pipes and tuggin on them is not enough need to test it properly.

You both might be in need of turbos though.
My turbo is brand new and has absolutely no shaft play. i've used starter fluid at all joints in Ic pipig while idling and motor did not rev at all. that ad I retighteed all clamps. that's what leads me to believe tehre's no leaks there.
 

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My turbo is brand new and has absolutely no shaft play. i've used starter fluid at all joints in Ic pipig while idling and motor did not rev at all. that ad I retighteed all clamps. that's what leads me to believe tehre's no leaks there.
Just because you checked the joints doesnt mean that there isnt a hole in the middle of the Ic piping.

Do yourself a favor and make up a tester, Its really easy and will save you lots of time! Do it properly.
 

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I don't have the stock IC pipig. It's all hard pipes. Upper and lower. I'm not finding a leak anywhere. My guess is the exhaust leak from turbo to elbow is causing the wastegate to leak and not hold boost. That will be taken care of when then new exhaust gets here, if that's one of the problems. I will check more thoroughly tomorrow. thanks for the advice.
 

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how do you know you C.A.C. is cracked of has a small hole in it? pressure the system up and use saopy water and start sparying then youll know for sure everything is OK as far as boost leaks
 

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how do you know you C.A.C. is cracked of has a small hole in it? pressure the system up and use saopy water and start sparying then youll know for sure everything is OK as far as boost leaks
Well the IC piping tested good today. no bubbles anywhere on the piping. I'm just waiting to see is the exhaust fixes it. It is leaking from the bottom where the wastegate port is. Hopefully my new DDP shows up quick.
 
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