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Help, what's happened to my boost???!!!

malc350

Well-known member
Joined
Jul 6, 2002
Messages
337
Location
Essex, UK
Corvette
1996 LT-4 Z51 CE
I have a 90 Callaway Twin Turbo. I just went for a drive and my boost seems to have gone. When I accelerate the car hesitates and if I hit the throttle too hard the car slows right down! The boost gauge peaks at 30 then just falls back down to 10 or 15. Previously the gauge would run up to 50 at full boost. The car ticks over perfectly and drives OK until I hit the throttle.

I've had a look for obvious vacuum leaks because that's the sort of thing I suspect. I have to confess that I loosened off the throttle body the other day to help line up the intercoolers and I didn't replace the throttle body gasket, could this be it? I also have a suspicion about the microfueller under the dash, could it be a vacuum line to thisor maybe the fuse?

The car doesn't throw out any smoke at all. It runs nice until I accelerate. Please help!!!
 
T

TurboLuigi

Guest
Malc,

Also make sure that hoses and pipes which connect the intercoolers are still in place and the clamps are on tight since you said you re-aligned the intercoolers.

I once had the tube which comes from driver's side turbo to the intercooler slide off because the clamp had loosened. So when it went into boost it pushed the pipe out of the rubber hose connector.

This is typical of turbo cars. It also used to happen to my '87 Grand National way back when (although my GNX hasn't done it yet).

Luigi
 

TAC

Well-known member
Joined
Feb 18, 2002
Messages
252
Location
Bothell, WA
Corvette
1987 Yellow Callaway TT Convertible & 2003 MY Z06
Wastegate failure can lead to both overboost and no boost. Overboost is more common. That's directly off the Callaway website. I don't think the Microfueler is an issue here. It uses manifold pressure and RPMS to determine when to fire the extra fuel injectors in the ram's horn. I don't think they control boost in any way.

There are good people in this forum who will hopefully have some ideas. You may also want to register at Corvette Forum so you can post there. Try paging Ultra Slow or 8388 in the ZR-1 forum and describe the problem, especially what you did to the engine prior to the problem. They both have 2 TTs and work on them themselves. Good luck.
 
9

90Callaway

Guest
malc350 said:
I also have a suspicion about the microfueller under the dash, could it be a vacuum line to thisor maybe the fuse?

The car doesn't throw out any smoke at all. It runs nice until I accelerate. Please help!!!

Hi Malc - First put the gasket (or better yet a new one) back on the throttle body. If you want you can test for a vacuum leak with some starter fluid (ether) by spraying it around the TB. If your idle speeds up you're sucking it in and there is a vacuum leak.

If that's not it, I think that the microfueler is your problem. Pull the panel from under the dash on the driver side. It should be tucked right up there. Check both the electrical connector and the vacuum lines. They both have a tendancy to come loose. (A tip- If your vacuum lines don't have plastic wire wraps securing them to the fittings, get some... it keeps them from popping off.) I had the exact problem you describe and the electrical connector to the microfueler had come unplugged.

But check the TB first since that's what you changed.
 

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