hey my friends driving an 89 turbo zx. i have a question about what's goin on with his car though. apparently he has a bad tps, i was wondering if that had any effect on the turbo... reason being he's only been able to get like 3 psi out of her. he was talking about ripping the turbo out and doin some crazy s*** to it... so i have no idea... any ideas?

Wouldn't it make more sense to replace the TPS first and see if it fixes the problem with low boost?

why does he think its the tps, whats his car doing?

well i told him to replace the tps first before touching the turbo at all. cause the thing is he's got a replacement turbo on a spare engine that he got with the car. so .....but about the tps i'm not sure what's wrong with his car that makes him think that... he may have ran it on a computer because he works at meineke, either that or he just took it out all together. another problem he's been having is his manifold will get to be red hott. i find that not too good. so my guess is his turbo's getting way too hott, which btw he has an intercooler.

Sounds like he could have a hole somewhere in the system, somewhere between the cold side of the turbo and the intake manifold. Could be in the intercooler, or one of the pipes. It could also be running lean because of the problem with the tps. That would make the headers glow and could cause the problem with lack of boost.

Red Hot Manifolds and Turbos are normal with turbocharged vehicles, you're looking at EGTs of 1000+ degrees, hell I've seen turbos and manifolds so hot that they lit up the entire engine bay.

As far as the TPS effecting the turbo, it can but indirectly. If the TPS isn't allowing the engine to spool up the turbo then you're not going to get a lot of boost. But other then that I don't know all my turbo experience is on Diesels, and they don't have a TPS.




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Saint wrote:Red Hot Manifolds and Turbos are normal with turbocharged vehicles, you're looking at EGTs of 1000+ degrees, hell I've seen turbos and manifolds so hot that they lit up the entire engine bay.

It's not normal on stock, or mostly stock, 300zx motors.

well that's what i was telling him, the computer didn't know when the throttle body was open, so the turbo didn't dump too much psi. i'm not sure, but what can be done with the intercooler to check for leaks? i'm just trying to help this kid out so i can race him with my cavalier? ha ha ha... .but seriously, i love his car and wanna see it run.

ChrisIDV wrote:It's not normal on stock, or mostly stock, 300zx motors.

That's right, like I said I'm used to Diesels that get used for 12 hours consecutively.

A lean condition will definitely cause High EGTs on a Gas engine, but IIRC the turbo is not computer controlled so the computer isn't going to pull boost, so I would go with a boost leak somewhere in the piping like Chris said.

To find the leak put a soapy water solution on all the fittings and look for bubbles, if there are bubbles you've found your leak. If there is no leak then I would look at rebuilding, or replacing the turbo.

A bad TPS usually cause hesitation and stumbling, and can stall the engine, if the car isn't having any of those problems I would forget about the TPS and just stick to the boost leak.




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rob linehan wrote:well that's what i was telling him, the computer didn't know when the throttle body was open, so the turbo didn't dump too much psi. i'm not sure, but what can be done with the intercooler to check for leaks? i'm just trying to help this kid out so i can race him with my cavalier? ha ha ha... .but seriously, i love his car and wanna see it run.

I dont think the problem is tps, the only problem i can see from tps like said above would be the car not letting the turbo spool at all, and that wouldnt overwork the turbo it would do the opposite. check to make sure the wastegate is working properly, (does he have an aftermarket boost guage?) if the wastegate is @!#$ then he could be running 20 plus psi, i was running 27 at one point when mine was messed up.

as for seeing if there are any holes in his system, a simple boost leak/leak down test will do that for ya.