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misfire/breaking up under boost

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Forgot about that.Pulled the can had 2 lobes gone.

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Mine was not to long after adding ported and polished heads with 100 lbs springs.

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I mean, i guess it could be cam, but it doesn't feel mechanical...almost electrical. It happens worse sometimes than others. I don't know what else to check though? Compression is good too, 150-160 across the board.
 
Mine was breaking up over 15lb of boost.
What I thought was an ignition problem was a head gasket that was starting to push itself out between the head and the block. It sounded like it was mixing up cylinders, and popping out the exhaust.
The car had great cranking compression, and otherwise drove absolutely fine.
I figured it out when the gasket finally let go.
 
Don't understand why you think the HG since your compression tested good
 
It is possible that the HG is showing its ugly face, only under boost. Look what gunslinger stated a few posts earlier, great compression and drove fine until under boost.
 
I don't see how head gaskets would cure a break up problem.

Has a good turbo Buick guy taken a look at it?

Rick
 
Nope, not like hitting a limiter. Here is what it sounds like, I actually caught it when I was doing a burnout at work. And no Rick, unfortanutely I don't have the $$$ to have someone else look at it. :/
That is how frustrating this problem is, I am willing to replace the headgaskets because I have tried nearly everything else. I cannot identify if it is mechanical or electrical. It never did this before I rebuilt the motor. It started to happen around 3-4,000 miles into my new build


Here are some things I have observed.

Bear with me here people, this problem is complete bullshit. It is very hard to identify.

It is more noticable at higher rpms.
When the problem occurs, the car picks up very little mph, but if I stay in it, it will eventually start pulling again.
When the problem occurs, boost rises, sometimes it is barely noticable, other times the boost will climb quite a few pounds, but it gets slower. I had it out on the highway, and I floored it. I have my boost set very low (11 pounds so I dont blow anything up). Boost stayed pretty steady at 11 pounds, then the car stopped picking up mph and my boost started creeping hard. I stayed in it for a good few seconds, and all of the sudden the boost DROPPED back down and the car started pulling again. The car smokes when the boost creeps, and then once the boost drops back down, the smoke goes away. I cannot tell if it is WHITE or BLUE smoke. But it definitely smokes.


Crazy. Pick my brain if that was not descriptive enough. I need mental help after this problem :(

You can hear it sputter right after the tires started spinning, right at the top of first gear.
 
Also forgot to mention, the boost problem occurs almost every time if I let the car downshift. If im doing 50mph, and I let it downshift into third, my scanmaster PEGS to 19.9 degrees of detonation, and boost goes up and the car doesnt go anywhere, then after a couple seconds the boost drops down and no detonation. It is not REAL knock, trust me. it happens no matter what boost level I set it at. Could the transmission cause this false knock?

Have I confused anybody yet?
 
Just replaced trans mount, crossmember bolts are tight. Will check trans bolts tomorrow
 
What are you seeing under boost for IDC injector duty cycle?
 
I had the rubber hose on a new fuel pump rupture in the tank. Ran fine until the boost came up, the injector duty cycle on the power logger showed the problem with spikes higher than normal. You can test the fuel pump with a regulated 20 psi air supply. You don't have to start the car just use the pump over ride connector to 12v and a pressure gauge. Add 15-20 psi to the vac line and observe the pressure increase.
 
Thanks for the input, but I do not think it is fuel related. It smokes when the boost comes up, and stops when it comes back down. It is gulping some sort of fluid when it starts to sputter.
 
Well since you said the plugs were lean looking I considered fuel, but you better check the water level next.
 
I have been slowly losing coolant. I think under boost its swallowing some.
Now when I say slow, I really have to look close at my overflow, but slowly and surely the level drops. I'm really anal about my car, i coolant pressure tested the system 3 or 4 times....every time it slowly lost pressure at 15lbs, but I always found a tiny leak or another that i had to fix. I did the last one about a week ago, and it was slowly dropping, my lower radiator hose was leaking just a tad, but honestly I don't think these are the causes of the drop. I was talking to my dad about it earlier, and he was telling me that it could be swallowing some coolant under high load, causing the boost to go up because of the bump in compression and smoking because of the coolant. Is this realistic? The only thing that throws me off is that it is not consistent, and it will show its ugly face especially under high load/rpm, then go away.


If anybody is intersted in taking a look at it, I would be more than glad to drive to where you are. I live in Central FL now, in Orlando. I know there is a Turbobuick group around here, and also a shop, but I would like a real guru to help take a look at it with me.
 
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