Getting psi and no codes but weirdly slow?

flyjum

New Member
Oct 5, 2006
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Mesa AZ
The car is a 87 7mgte. R154 trans and stock everything. Well we just fixed it and runs good... kinda. Well when we drive it runs good till it hits boost and bogs and sputters and does not accelerate. Could a bad bov be the problem? WHen we rev in neutral it sounds fine( bov seems very loud for stock) and it holds 7 psi even when driving. But it just bogs out. So what i was thinking is maybe the BOV is stuck open or something. Also after just 2 mins or so of driving the turbo gets red hot for real. And turns white when it cools. Maybe a boost leak? Please help. Can i cap the bov off and run it around the block or would it be to bad for it like surge or something?
 
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jdub

Official SM Expert: Motor Oil, Lubricants & Fil
SM Expert
Feb 10, 2006
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Valley of the Sun
Check your timing...sounds like the CPS was installed off a tooth or the timing belt is off a tooth.
 

starscream5000

Senior VIP Member
Aug 23, 2006
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Hot and Humid, KY
Don't cap off your bypass valve. If you think it has a boost leak, then check for it, but you're not throwing codes right? Do you still have the original cats on it?
 

jetjock

creepy-ass cracka
Jul 11, 2005
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It has to be a bad BOV right? Doesn't matter that a bad one couldn't cause these symptoms. And it couldn't possibly be something done wrong to the car while "fixing" it. Fascinating.

The dead giveaway is the turbo...
 

Caplax40

Grand Tourer
Feb 12, 2006
202
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Boise, ID
jdub said:
Check your timing...sounds like the CPS was installed off a tooth or the timing belt is off a tooth.

Agreed. That sounds similar to a problem I had when the CPS was off one tooth. Car would rev and boost (kinda) but we would go no where and the engine ran like crap. It was abnormally hot in the engine bay and was puking a small amount of coolant.


Althought I am intrigued by what Jetjock is saying with his sarcasm. I can't tell if he's trying to hint at some other problem. Speak it Jetjock!
 

jetjock

creepy-ass cracka
Jul 11, 2005
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Sorry, I don't do spoon feeding. Not when it comes to basics. I was simply amused how the poster seems to think his problem is unrelated to the work recently done on the car. I'm also amused at the seemingly endless number of posts about engines that don't run right after they've been worked on. That's assuming they even start. It indicative many people are using the book as much more than a crutch. The purpose of a service manual is not to teach basics. It's written with the assumption those using it already know them.

The whole CPS thing is funny. Many don't seem to understand the theory behind what it does. I was recently talking to an young owner about this and he agreed, saying he'd had to fix several improperly installed CPS for friends after they'd work on their cars. In discussing it with him I found out he thought as long as cylinder number 1 was at TDC on the compression stroke the CPS shaft could be installed without regard to orientation with the CPS housing. He swears that's how he's been doing it all along. Just stuffing it in there. Ok, if he says so.

Which begs a question: If the CPS housing didn't have a slot for the bolt and the wiring was long enough so the housing could be rotated 360 degrees would having it "off" one tooth (or many) matter? Could the CPS, as he claimed, be installed in the head with any orientation as long as # 1 was at TDC on compression? Could the engine ever run? If so could timing be set? Since one camshaft drives the CPS assume valve timing is correct.

That aside the OP needs to ask himself why the turbo would do what it's doing. It's not like there's a lot of reasons.