Turbo's don't boost

I just bought a '90 300zt TT from Texastoys.com. Bad idea, never buy from them...rip off artists and liars. Anyways I just rolled it off the truck and went for a spin and the turbos won't boost. I get the typical -14 up to 0 boost pressure on the gage, but they won't engage positve boost. Any ideas? Stuck wastegate maybe? Car has 125k miles on it, clean, good condition inside and out. Only driven 9k a year average.

Are you sure its not a gauge problem? That it stops right at 0 PSI on what I am assuming to be the factory gauge sounds odd to me. Even blown turbos will sometimes make a few PSI.

I'm positive it's not a gage problem and yes I am refering to the factory in-dash boost gage. I have a modified Porsche 951 Turbo so I know what a boost should feel like. This has nothing, not even 2-3 psi. Also my brother-in-law just bought an '93 300zx tt automatic, so I know it's the car. It's more anemic than a non-aspirated car right now. It actually seems to bogg slightly under the load of the throttle. Kind of worried since the car was supposed to have a warrantee but doesn't.

Do the turbo's just up and go out on these or is it more probable to be something minor?

A '93 350zx Twin Turbo eh?

:lol:

I kind of agree with Broke on the subject here... Even a turbo with a cracked compression housing will still boost.

I saw once, a Twin Turbo Zed, and somehow the aftermarket BOV's were stuck open, and no boost was going by.

Is the Zed completely stock?

I would just suggest taking it to a Mechanic, to be perfectly honest.

-Wes

HUGE typo --'93 300 TT my bad. Identical to mine, but his is auto and white. Mine is black and manual. Yeah, I will be taking it in tomorrow. I was just hoping it was one of those things a seasoned veteran on here would be able to go..."sure that's common, check this." before I took it in. So the odds of it being a relay or connector is probably right out.

Yeah Samhain as far as I can tell from the 6 miles I drove it, it seems to be bone stock. Stock exhaust even. Only thing I saw were K&N filters.

I was just hoping it was one of those things a seasoned veteran on here would be able to go..."sure that's common, check this." before I took it in.

Not even seasoned veterans have seen everything. Let us know what it is so we can learn from this.

It's obviously boosting some because an intake is under vaccume with the engine on due to the engine sucking air through it. Why the turbos only push enough air to bring the pressure up to 0 is odd. I would say that it could be safety boost, but that doesn't cut boost all the way to 0.

I too would have to say to take it to a shop. Have them run a diagnostic check and see if the ECU is throwing any codes. Don't lose hope...it still COULD be something not too major.

Something sounds really sketch to me... I've seen COMPLETELY blown turbos spooling. On my buddies Saab 9000Turbo, his exhaust housing cracked in half... But the turbo still hit at about 4grand (just about 1,000RPM late... But still it hit)

All im saying is something seems weird... Go get the ECU checked like LLTZ said.

-Wes

OK. Took the car to a Japanese car specialist and they told me there is a small leak in my cooling system and an oil leak around the turbo housings. They tell me that this is where my boost pressure is going. Does this make sense? If so, there you go guru's. Next time someone posts this problem you can go "Yeah, I've heard of that before, check for this."

Well...not really...only way I can really think of that an oil leak would be releasing boost pressure would be if the oil seals around the turbo shaft were shot. Whatever it is...it either sounds like a large problem, like a turbo has a crack or a gasket leak some where or a really simple problem like the boost sensor is reading wrong or something...the whole thing just sounds strange.

My guess... Boost leak 125k Miles completely stock. Rubber boost hoses going into the TB's could possibly be cracked. I would inspect those. In hot texas heat a 10 year old car that sits can't be a good thing. Also check other boost hoses in the engine bay. Is there a possibility the car has a manual boost controller that you dont know is in the engine bay? Check the sensor on the driver side of the engine bay where the small boost hose connects and trace it see what you find...

Also check the intake balance tube rubber gasket... the black bar that runs across the top of the motor that thing can cause serious problems...

Nice car, LA. Haven't seen you on here before.

This whole thing sounds very odd. That stuff the mechanic told you doesn't make any sense to me.

Come to find out the mechanic now says the left turbocharger is fried from the oil leak. Says it wasn't getting sufficient oil and the wastegates were rusted shut! Can anyone direct me to a place to pick up a used or refurbished turbocharger that won't cost me an arm and a leg???

Beware of Texastoys.com they are con artists!!! Spread the word.

Wow...how you going to rust shut a wastegate...maybe if the car sat outside for a couple rainy months...anyway...if the turbo really is fried...well now my be a good time to upgrade if you were going to do that. In the factory manual they have an outline of how to remove the turbos while the engine is in. Having pulled my blown motor and seen how they are fixed to the engine I can tell you this:

It ain't going to happen. Its a trick to the the ****ers off when the engine is out.

So, if the turbo is truly blown, then the motor got to come out to replace it, but if you want to, you can drive it on a blown turbo...just won't be much fun. VG pulling incurs huge labor costs however. Buying another turbo would be the least expensive part of this deal. A brand shiny new factory pair from Nissan ran the guy who used to own my car just under $1000. But usually you can find someone who just upgraded their turbos and have their stock ones for sale. You could probably find a decent used left one only for less than 200, easy. Only problem there is that most people don't want to break up a set.

BUT, I don't know if the mechanic is a friend of yours or something so not to insult anyone but it sounds like the guy is just taking shots in the dark. If you can get the car to a Z specialist then try that, however, those shops usually cost more.

Rusted shut waste gate would create an insane amount of boost becasuse at high rpms more exhasut gas is flowing a "wastegate" is the excess exhaust gas that would creat to much boost other wise. Rusted open or broken actuater stuck open is diffrent. But then again low end driveablity would suck. Plus the fact it would probably not want to idle. Most of the time messed up wastegates are from too much boost. Tell your mechanic he sucks and take it to a specailist (not tryin to be mean but the story changed 3 times arelady)

That's not too reassuring. Car didn't have any of those attributes. It did idle a little high while cold (2K+), but other than that it ran smooth-yet VERY lakcing for throttle response. He may have meant that it was stuck open then...??
What sucks is they ARE the only specialists around here for this type of car.

Wow...that song "Shot in the Dark" by Ozzy comes to mind. That mechanic seems like he's just pokin around blind. If the wastegate was rusted shut, there would be no controll over your boost...it wouldn't stop until something broke. If it was rusted OPEN, then THAT would make sense...that would explain why no boost can build.

Gunna toss an idea out there...think he could bypass the broken wastegate and use an external wastegate as opposed to replacing the whole unit? This might be an alternative unless he really DOES neet to replace it...which no one (even his "mechanic"...no offense, dude...) seems to be too sure of.

If you do have to replace it, you might as well upgrade while you're at it.

its an idea but i dont know how you would go about keeping the internal wastegate closed??

That's not too reassuring. Car didn't have any of those attributes. It did idle a little high while cold (2K+), but other than that it ran smooth-yet VERY lakcing for throttle response. He may have meant that it was stuck open then...??
What sucks is they ARE the only specialists around here for this type of car.

Then I would suspect you have a boost leak thats quite serious if everything is good.