Turbos not spooling?

[Flapjack]

Went to take the car to the dyno today. On the way there, I noticed it was only making about 3psi. I got to the shop and let the guys know I'd be a few minutes while I investigated.

Even in first, it only is making about 3.5 to 4psi. Springs are 7.5psi, and the EBC is set to a 50% duty cycle, which nets me 12psi.

I haven't driven the car in about 2 weeks. It seems to be running fine. No loose vacuum hoses, intake tubing, etc... I never actually hear the gates open.

The kit is a THP twin kit. Never had a problem making boost before today.

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[stang67gt]

If you can, check to see if your wastegate isn't partially stuck open.

 

[19COBRA93]

How does it sound? Can you hear the turbos winding up? On one of my turbo '93's I had an intercooler weld split, it wasn't much of a gap, but I couldn't build more than about 3lbs. I could hear the turbo winding up, but no boost. We had to do a smoke test to actually find the leak it was so hidden.

I'm betting on a leak somewhere between the turbos and the intake manifold.

 

[JeremyH]

Sounds like a boost leak somewhere on the coldside, they can be very tricky.

 

[Flapjack]

If you can, check to see if your wastegate isn't partially stuck open.

How can you check it?

How does it sound? Can you hear the turbos winding up? On one of my turbo '93's I had an intercooler weld split, it wasn't much of a gap, but I couldn't build more than about 3lbs. I could hear the turbo winding up, but no boost. We had to do a smoke test to actually find the leak it was so hidden.

I'm betting on a leak somewhere between the turbos and the intake manifold.

The turbos start to spool and have a good whistle to them, but it never sounds like the wastegates open. They're by far the loudest part of WOT, so I'd be able to tell if they're open. The guy at the shop says one or both may be partially stuck open, but both seems highly unlikely.

Sounds like a boost leak somewhere on the coldside, they can be very tricky.

That's what I thought, as I've blown the intake tube off a few times, but I couldn't see anything out of place.

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[one eyed willy]

I vote cold side....

 

[retfr8flyr]

Do you have a boost controller on the car? If so it could be the solenoid on the controller. I had the same thing happen with mine when I had a different controller on the car. It would make W/G spring pressure but that was as high as it would go because the solenoid wasn't working correctly. My W/G's did open though, so it's probably a leak in the cold side but it must be a large leak.


Earl

 

[Flapjack]

I vote cold side....

Starting to think that way, too. Simply because I should've heard at least one wastegate...

Do you have a boost controller on the car? If so it could be the solenoid on the controller. I had the same thing happen with mine when I had a different controller on the car. It would make W/G spring pressure but that was as high as it would go because the solenoid wasn't working correctly. My W/G's did open though, so it's probably a leak in the cold side but it must be a large leak.


Earl

I do have a boost controller, but I'm not even making spring pressure. I did go through the EBC settings, just in case. I've kinda rule it out at this point, though. If it was stuck open, I'd see a lot of boost. If it was stuck closed, I'd see spring pressure... right?

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[retfr8flyr]

Yes it should, that's why I also think it has to be a cold side leak. I just don't see how it could be that big of a leak and you not already notice it.


Earl

 

[Flapjack]

Yes it should, that's why I also think it has to be a cold side leak. I just don't see how it could be that big of a leak and you not already notice it.


Earl

Yeah, I don't either. It was fine last time I drove it.

It's at my old house. I'll get it home this weekend and up on jackstands...

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[michael.konor]

If your wastegate wasn't opening, wouldn't you overboost? In any case, you could eliminate the boost controller if you reconnect the wastegate vac/pressure line directly from the turbos to the wastegate and then see what your boost level is.

If not there, I'd start tearing into the cold side.

BTW, how's the idle and un-boosted driveability? Changed?

 

[Flapjack]

If your wastegate wasn't opening, wouldn't you overboost?

Yes, but I don't think it's stuck closed. at this point, I don't think it's opening either. I'm not building enough pressure for it to open. They're either stuck open (don't think so, because I can't hear them at WOT), or there is something wrong on the cold side. This weekend will be the soonest I can work on the car. I'm suspecting either a clamp loose somewhere, or maybe the BOV stuck open.

In any case, you could eliminate the boost controller if you reconnect the wastegate vac/pressure line directly from the turbos to the wastegate and then see what your boost level is.

I can try that. I think I would just remove the lines from the top of the WGs first, though. At that point, the EBC would not be controlling anything and I should be seeing spring pressure. I still don't think it's the EBC, because no matter what it is wrong with it (if installed right), I should always see at least spring pressure.

If not there, I'd start tearing into the cold side.

That's the plan for now. I'll get it up on jack stands, pull the bumper cover off, and inspect every single clamp in the system.

BTW, how's the idle and un-boosted driveability? Changed?

It drives great... like a dream. Idle is good, acceleration is smooth, I just don't have as much boost/power as I used to.

 

[one eyed willy]

a must have for all turbo owners!

http://www.s197forum.com/forum/showthread.php?t=89154&highlight=smoke+machine

 

[Flapjack]

a must have for all turbo owners!

http://www.s197forum.com/forum/showthread.php?t=89154&highlight=smoke+machine

I've stumbled across your thread. Pretty damn nice. Wish I had the time/patience to build one. I can barely finish all the damn projects I have started now.

Care to build one for me? I'll pay you.

 

[Flapjack]

Figure it out. I found some time to get the car up on jackstands. Of course, it was one of the clamps I couldn't see with the car on the ground.

 

[JeremyH]

Suprised you had any boost at all with a leak like that!

 

[Flapjack]

Suprised you had any boost at all with a leak like that!

No kidding.

The piping is a fairly tight fit, so there wasn't really any place for it to go. The air charge must've been mostly crossing the gap until the pressure increased.

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[one eyed willy]

you should fire your installer!

 

[Flapjack]

you should fire your installer!

Hahahha!

It was fine for the past few years at 7psi. I guess it didn't like the bump to 12psi.

 

[retfr8flyr]

Glad you found it, I had my connection at the TB blow off on the dyno at 20#. It had been fine until then.


Earl