So Saturday I was driving the GN around and decided to gradually get into the throttle, boy did it feel good. So I decided to gradually get into it again and then I commence to hear this sound under the hood- it sounded like there was a balloon deflating but someone was stretching the balloon opening while the air was being let out. Then my fuel pressure gauge went from about 32lbs to 20lbs. So I drive home expecting to see the intercooler hose blown off at the throttle body and it was still intact. I was able to adjust my fuel pressure back to 32lbs but the fuel pressure seemed a little unsteady. I can't build any boost while driving or foot braking the GN. I do hear was sounds like a very loud spooling noise from the engine compartment but it won't build any Boost. I've checked the oil- no water in it, GN is not smoking, not getting hot, oil pressure is good. The puck on the TH downpipe is intact. The turbo impeller on the hot and cold side spin freely. There is some impeller movement from side to side. While trying to rotate the impeller and moving it from side to side, at the same time, the impeller gets into a bind. Need Help.
No Boost
- Thread starter 1QUIK6
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SFI Cutlass
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- Joined
- Jan 2, 2010
Maybe a bad fuel pressure regulator or fuel pump?
Thanks for all the replies. Well, it looks like it's the hot side impeller of the turbo. Looks like there's a chunk missing from the impeller. See picture below. I guess this would cause the loud spooling sound with no boost. I still don't understand why the GN would have lost fuel pressure like it did though. Any ideas?
agreed
I thought that boost would be affected by the puck not sealing? About 2 months ago I was able to run 25psi boost at the track and it seemed pretty stable at that level. Only thing, I do remember is that I had to really work on getting the waste gate actuator rod on the waste gate. I had to really pull on the rod to get it on the waste gate linkage. Anyway to fix the puck not sealing?
- Joined
- Sep 24, 2010
Somethings up. Without a sealed puck, you're going to have some slow spool and might not even be able to get up to full boost.
You said you had to stretch the hell out of the rod to hook it up so that could only mean two things. Either a mechanical problem that won't let the puck swing all the way to the housing (easy enough to check since the DP/elbow is off), or somethings up with your wastegate can and fully retracted isn't far enough back to seat the puck.
You said you had to stretch the hell out of the rod to hook it up so that could only mean two things. Either a mechanical problem that won't let the puck swing all the way to the housing (easy enough to check since the DP/elbow is off), or somethings up with your wastegate can and fully retracted isn't far enough back to seat the puck.
- Joined
- May 25, 2001
There is a chunk out of one of the blades on the exhaust side, that turbo is toast. On the DP what does the puck look like? The pic post #2 in this thread is what the witness mark on the turbo should look like. Boost creep/ wastegate hole porting
- Joined
- Sep 24, 2010
Here's a pic of the puck on the TH downpipe. Turbo is toast, dang it. Any idea what would cause this?
View attachment 293028
View attachment 293027
I'm no expert, but none of that looks right
Is it a "real" TH downpipe (you're sure?) or is it possibly a low quality knock off?
What is stopping the puck from sealing? Is the actuator adjusted right? Doesn't seem so.
You obviously need a new/rebuild on the turbo (get a new one) but the puck issue needs to be addressed or you will just be pissing into a fan.
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i see a witness mark on the puck.... but only on half. It looks like it won't lay flat on the exhaust housing and from the picture it seems to show evidence of erosion on the DP flange. Much like it's been hit by a torch for a little while.
If you lay a straight edge across the DP flange, the puck should lay flat on it when closed. If it hits and it's crooked, you found your problem. If it hits in the center of the 'crescent moon' witness mark you've defiantly found your problem.
If you lay a straight edge across the DP flange, the puck should lay flat on it when closed. If it hits and it's crooked, you found your problem. If it hits in the center of the 'crescent moon' witness mark you've defiantly found your problem.
Sandblast it, fixture it in a milling machine and mill the flange. Then use a plate to re-locate and re-size the hole. Remove exhaust housing and machine the exhaust outlet side and inlet side flat. Turbo is shot with blade missing but this is a list of what would make a drastic difference in performance
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I bought the downpipe from a very reputable company that sells turbo Buick parts. It was supposed to be a genuine TH downpipe. I checked the waste gate and it seems to be moving very little. It was supposed to be a HD waste gate actuator from the same company. I had to get about 20#s of air pressure for it to move. I am wondering if the internal waste gate is the way to go? I was at the track a few months ago and the car ran pretty good, ran an 11.7 @ 117. I've always thought that it should be faster?
There were two THDP designs produced back when he actually was making them. One for stock headers which didn't get close to the fenderwell, one for ATR style headers which swung out much further and was close to the fenderwell.
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