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Discussion Starter #1
Hey everyone,I've been trying to figure out my car for 2 years now. I'm just about ready to give up and go N/A. Here's my setup:
5.0 stock rebuilt bottom end
TW 170 heads /1.6 RR.
Trickflow stg 1 cam
Systemax2 intake
39# injectors with PMAS maf.
255 fuel pump.
2- T3/T4 .60/.63 turbos,external gates,50mm bov.
Tko600 and 3:73's
Sct chip.
Here's the problem. When I start to roll into the throttle it won't hold any boost,it flutters back and forth between 1-3 psi. It seems to work fine in first gear and sometimes in 2nd. It's making a sound like the bov is opening and closing. What would cause it to not hold boost?i had it on the dyno twice and both times it would cut out around 3500rpms. Any ideas?.
 

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Have you checked the BOV and wastegate to make sure they are working right?

Make sure the BOV is closed when you go WOT.

Make sure the wastegate is not opening up too early.
 

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Discussion Starter #5
The bov is from RPS and I believe it's a 12# spring. The wastegates are turbonetics with 7# springs and I added 2 washers. The reason I put those springs and washers is because I thought the gates were opening early.
 

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easy way to tell would be to remove the gates and bov and block off those openings and see what it does. just be prepared to back off quickly before it boosts to the moon lol.

then put on the bov the way it was (do same for wastegates) and see what happens. whichever one causes the no-boost condition is where you should look.

but yeah, this is the shadetree way :p
 

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That seems dangerous/ pointless.

You could easily watch/ feel the bov to see if it opens up when you get on it on the dyno, same with the wastegate.

its pretty obvious when it opens.
 

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Discussion Starter #8
What would cause the bov to open up under throttle,shouldn't the boost pressure keep it closed?? Maybe I should pressurized the intercooler to see if that's got a leak. Also, what are your thoughts about the SCT chip? There's so much going on with this car,it idles at 2k,it bucks when off the throttle. I think I'm gonna end up pulling it all off. I just want to drive my car.
 

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Were you having it tuned when it was on the dyno? If so what did the tuner say. I'd say a good rep tuner can knockout all your problems
 

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What would cause the bov to open up under throttle,shouldn't the boost pressure keep it closed?? Maybe I should pressurized the intercooler to see if that's got a leak. Also, what are your thoughts about the SCT chip? There's so much going on with this car,it idles at 2k,it bucks when off the throttle. I think I'm gonna end up pulling it all off. I just want to drive my car.

Who knows, bad vacuum source maybe? Weak spring? Have the vacuum run into the wrong port?

You could pressurise the whole system with the lowes pvc plumbing trick.

Drill a hole and put a compressor quick connect on it and pressurize the system.

It really sounds like you need to get the car to a competent tuner.......
 

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Discussion Starter #11
Yes this did happen twice on the dyno,he was tuning the sct6600 chip and it kept cutting out around 3500. He first thought it was an ignition issue,so I swapped back to stock ignition and had same problem. He then thought it could be spark blow out but I've had people telling me it's not that. There's not too many places around here for these cars,I'm limited to 2-3 shops. Let me ask this...I swapped from auto to manual and kept the A9P,does this make any difference?
 

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im running the RPS bov on my car with whatever spring it had in it when i got it and im not having any problems. My car is twin turbo also. If you put the weaker spring in it you should swap it out and see what that does.
 

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Discussion Starter #13
I've tried both springs with the bov. Davidz,what are you using for tuning? Someone mentioned to me that it sounds like unmetered air getting in.
 

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Sounds like it could be a few problems..... If you're only getting to 3500 rpm and you have an exhaust leak or vacuum leak you probably wont see boost anyway

Sounds like you have a few issues.
 

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Discussion Starter #16
I'm going to test everything for leaks. The only thing is this happened when I had a stock motor,then I ripped everything out and rebuilt the motor and it does the same exact thing.
 

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It happened on the stock motor with no turbo kit?

Or the stock motor with the turbo kit?

Its obvious you have a problem somewhere and swapping a motor in isnt going to fix an issue with some other component.

Maybe you have bad MAF? When my car had a bad MAF it would hit a wall around 3500 rpms and just die.

Not sure what to tell you at this point, get out there and test some things on the car.
 

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Discussion Starter #18
It happened on the stock motor with the turbos. I had plans to rebuild it anyways. My first setup I had a C&L maf and then I swapped to the PMAS. I'm going to test everything for leaks and see what I get.
 
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