boost... but no pull?

[daveyfx]

Hey all, I've got an odd issue going on here. I've got a 1999 GS-T running on a 14b, which is in perfect working order. I've got lower and upper hard pipes and a 1g BOV. Did a test for boost leaks and I have none. Now, on to the issue and symptoms I've noticed...

Light throttle acceleration is decent for the most part but once I go over 50% throttle, the car falls on its face. It makes full boost (no leaks) but I literally go nowhere.

The problem is much worse on warmer days. For instance today (83 degrees here) I sat at 2,000 rpms and gave her full throttle. Built boost fine and the car proceeded to barely crawl along.

On cold days, I notice the problem a lot less, part throttle pull is much better then too and full throttle pull isn't nearly as bad but it's still embarassing.

Ideas?

 

[ChrisFlo]

Sounds like a spark plug issue to me. Try pulling them to see what kind of shape they're in. My car did the exact same thing with bad plugs. Ignition wires could be a possibility as well.

 

[daveyfx]

Hmm, thanks I will give that a try bro. The weirdest thing is that I drove the car around up north after it was acting like this in the hot South. It was in the 20's up North and the car pulled hard at full throttle.

 

[Majite]

You could be heat soaking the intercooler. I know its only a 14b but you are in florida. Also you said it pulled fine up north where it is cooler. I would check that.

 

[daveyfx]

It did it with the T-25 too. I thought I was just experiencing some bad compressor blowby because the lower intercooler pipe had some oil around the edges but when I swapped to the 14b the i/c pipes were clean, so was the i/c, and the turbo had hardly any shaft play.

So I basically swapped the turbos for no reason... well... not that I was fond of the T-25.

Anyone else got any ideas?

 

[tsibryan]

I had this problem as well, on my '90 TSi AWD. But it's not constant. Sometimes it spools and pulls fine, and then a couple hours later it will spool but not make any power. I don't have a real boost gauge, but I was beginning to think maybe it was the BOV sticking open, or maybe something with the wastgate.

 

[oldman]

Check timing, compression test.

 

[daveyfx]

Check timing, compression test.

oldman, I do not mean to come across as disrespectful by asking this but my compression test came out clean, I have not checked timing but the previous owner had the belt changed and new water pump installed.

would either bad compression or timing be sensitive to temperature changes?

i hope it's something as simple as an ignition issue. WTF

 

[daveyfx]

I've got a 1999 GS-T running on a 14b, which is in perfect working order. I've got lower and upper hard pipes and a 1g BOV. Did a test for boost leaks and I have none. Now, on to the issue and symptoms I've noticed...

Light throttle acceleration is decent for the most part but once I go over 50% throttle, the car falls on its face. It makes full boost (no leaks) but I literally go nowhere.

The problem is much worse on warmer days. For instance today (83 degrees here) I sat at 2,000 rpms and gave her full throttle. Built boost fine and the car proceeded to barely crawl along.

On cold days, I notice the problem a lot less, part throttle pull is much better then too and full throttle pull isn't nearly as bad but it's still embarassing.

Ideas?

 

[Pulsr]

I had the same problem for a while except my car would jolt in the process. Comes to find out it was my turbo to manifold gasket. It was split in half. Replaced it and the car purrs like a kitten again. My experience with boost build and no pull...

 

[daveyfx]

See, I thought I had bad compressor blowby because my T-25 wasn't pulling either. I replaced the gasket when I swapped to the 14b and I still have the same issue with not pulling.

Feels like the timing is being pulled severely, the car acts like it's driving through a lake of molasses unless I'm at light throttle...

 

[Syndicate13]

That sounds like a big boost leak. How exactly are you checking for leaks? If you aren't getting enough air into the system then you may have leaks you don't even know about. I would also suggest either getting or finding someone with a logger and log the car during this. If your timing is unaffected then it's a boost leak, if timing is being pulled then it's knock from somewhere.

 

[daveyfx]

I built the leak tester and pressurized the whole system at 10psi. Didn't get leaks from anywhere. I originally thought a bad boost leak as well except it ran perfect in 20 degree weather up North, .

 

[daveyfx]

Anyone else got any ideas as to why my timing is maybe being pulled severely?

 

[Syndicate13]

Knock. Either real or phantom. How much boost are you running? Please tell me you have an actual boost guage in the car and are not relying on the stock one. I would take my advice in your other thread and log the car to see where your timing is at, if it looks low then you are knocking, if not boost leak.

 

[Defiant]

Do not cross-post.

 

[oldman]

I built the leak tester and pressurized the whole system at 10psi. Didn't get leaks from anywhere. I originally thought a bad boost leak as well except it ran perfect in 20 degree weather up North, .

10 psi is not enough. If 10 psi was all you were able to build, it's clear that you still have some leak not fixed yet. Perform the test again and don't stop until you reach 20 psi.