Losing boost at 6400rpm. Help!

[jmcboost]

You may have already tried this, but I thought maybe if you are using adjustable cam gears (can't remember if you do or not), take them off and use the stock ones. :dunno:

 

[suprahero]

What will this do? I still have my stock cam gears, but I don't know what swapping them will do for me. I will try again to set them to where I had them at when I made the most power on the dyno, but even when they were straight up, like they are now, it made good power with no loss of boost.

Thanks for the suggestion though and keep them coming.

 

[buckshotglass]

Do you have me and Scott on ignore?? sheesh.

I'm not smart enough to agree with you here Dave.

I'm trying to dumb down and think of the basics.

 

[suprahero]

sorry Dave. I didn't know you and Scott had posted. I thought Mcboost was the first one to post after my post.

As for the intercooler, Ricky tested it for a boost leak and it passed with flying colors. I guess it wouldn't hurt for me to take it off and test it myself personally. I can buy a few fittings from Home Depot and plug one end off.

 

[buckshotglass]

It's not leaking, it's restrictive.

 

[suprahero]

I don't know how it can be restrictive. It made 543 rwhp not too long ago.

 

[OneJoeZee]

Hi, Jay.

 

[buckshotglass]

Sup Joe. Long time.

Jay, was that pre Texas? Maybe you clogged it on that trip, or a mouse made a house, or.. Bypass it and get back to me.
Stop by tomorrow and I'll take a look.

 

[bigaaron]

I have also replaced the valve that controls my AVC-R with a MAC valve. I thought it might be something with the boost controller since it's so precise, but that hasn't changed anything. It still does it at the same point everytime.

Have you pulled the exhaust housing off the turbo to inspect the exhaust wheel? When my 7m Ross pistons failed, pieces of the pistons damaged the exhaust wheel and it didn't make much boost.

 

[bigaaron]

You may have already tried this, but I thought maybe if you are using adjustable cam gears (can't remember if you do or not), take them off and use the stock ones. :dunno:

That's a bad idea with Crower cams, they were already degreed and adjusted with the adjustable cam gears.

 

[buckshotglass]

Aaron, I think he got a new turbo.

 

[Slow_Sc3]

try a tial 18psi wastegate spring see if it will hold the 18psi since the 13lb spring might not be enough for your turbo and 17psi.... thats just a long shot in the dark tho it would help me out a ton it i could see the car in action.

use the 18psi spring and no boost controler and have the vac line to go the back of the intake manifold.

 

[bigaaron]

It's open wastegate, so if the wastegate was opening before the target boost, the sound would make it obvious that it was leaking.

 

[Slow_Sc3]

It's open wastegate, so if the wastegate was opening before the target boost, the sound would make it obvious that it was leaking.

Cool dude.

The wastegate is still going to be open @ 17psi and 13psi since its losing boost/ not holding it. my guess is the wastegate is still open and he has his vac lines hooked up wrong or dieing EBC.

tial with a 13psi spring not holding 17psi.... sounds like a boost controler problem.





one way to fix this is get a nice jug of C/Q16 and pull the wastegate line and start the tuning.

 

[bigaaron]

Cool dude.

The wastegate is still going to be open @ 17psi and 13psi since its losing boost/ not holding it. my guess is the wastegate is still open and he has his vac lines hooked up wrong or dieing EBC.

I agree with the boost controller being a possible issue, but in this case I thought he mentioned to me that it would not boost over a certain level even though the wastegate was still closed. With an electronic boost controller, the wastegate stays shut until just before the target boost, so it would not be open at 15psi if it was set for 17psi. You can still hear the difference. If the wastegate opens at 13psi normally, but then the wastegate stays closed with the boost control set at a higher boost level and it still will not make more boost, then the boost controller and wastegate is working and there is some other issue. First thing to try is like you said, connect the vacuum line from the turbo outlet to the top of the wastegate and it should boost to the moon (set the boost cut on the ecu first!)

 

[suprahero]

Have you pulled the exhaust housing off the turbo to inspect the exhaust wheel? When my 7m Ross pistons failed, pieces of the pistons damaged the exhaust wheel and it didn't make much boost.

I thought the 35r was causing it since I"d replaced everything else, so I bought a pt67 from a local guy here. It does the exact same thing, only sooner now.

Thanks Dave, I'll see if I can stop by tomorrow sometime.

 

[ForcedTorque]

I may be wrong, but didn't this problem persist, with the boost controller turned off or disconnected, prior to the turbo swap?

 

[jmcboost]

That's a bad idea with Crower cams, they were already degreed and adjusted with the adjustable cam gears.

OK, I understand that. I just figured if he had adjustable cam gears to take them out of the equation. I didn't know about the crowers.

 

[bigaaron]

I thought the 35r was causing it since I"d replaced everything else, so I bought a pt67 from a local guy here. It does the exact same thing, only sooner now.

Thanks Dave, I'll see if I can stop by tomorrow sometime.

That's a lot more money then just a simple inspection of the turbo, if it was causing a problem like this it would be obvious. Either the shaft wouldn't turn or the compressor or exhaust wheel would be damaged. I wish I could see it in person, we could probably figure it out in 10 minutes.

 

[IJ.]

J Told me he bypassed the Boost Controller plumbing the WG directly to a boost source and did the exact same thing.

Can't say I'm surprised that shimming the valve springs didn't help as 70 pounds seat pressure was adequate.