no boost under load

superdadsc

Registered User
I have no boost under load. The car falls on its face.
Checked the ic. Putting car on a smoker.

Any ideas?
 
Check the bypass valve.

Is the flat-face a stumble or just no power but revs ok otherwise?
 
It dies like it is going to stall. Completely losses all power and wants to die, then you let off the gas and it will drive under vacuum.
 
Done any work to it lately?

Run the codes yet?

Starts right up?

No check engine light?

Plenty of fuel in the tank and volts in the battery?
 
Yes it has a new motor:D. It has about 500 miles in it. Idles great, and ran great but only had about 8 or 9lbs of boost. I thought I had SC belt slip so I swapped the tensor.

Driving the car you hit the gas and it will fall on its face. You can hear the blower spinning and getting louder, the boost gauge goes to about 9 or 10 lbs but she will fall onto its face and if you kept your foot on the gas it feels like it will stall. Let off the gas and she drives great.

The car did not have this problem for about 500 miles.

No codes,no lights, half a tank....she starts right up and idles and revs great. It happens under load!!:mad: Has it on a smoker and everything looked fine.
 
Odd, I think - you might need to check for a plug wire that fell off or got burned and/or read the plugs and consider doing a compression check.
 
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Did you check the supercharger and jackshaft belts? I had a supercharger belt break on me, and it was exactly the same symptoms. I zip-tied the bypass open to drive it for a couple days until I got the new belt, then all was well.
 
I had a very similar problem. I could slowly ease into throttle to about half throttle before it would act stupid or if I floored it it would stumble and back fire. No check engine light. Turns out I fouled a newer set of spark plugs doing a burnout up to rev limiter when the engine was cold... I blame miller brewing company for that. I replaced the plugs and solve everything. If its not that. Check fuel filter and fuel pressure at idle and rev. I believe 40psi is what mine runs at idle but I could be wrong I can't remember and it has an aftermarket pump. If that all checks out move onto the maf sensor. Simply pop it out and make sure that both of the wires inside (the filament type things that bridge the 2 sets of tongs) make sure they are a silvery white color. If there not just clean with rubbing alcohol and a que tip. Be careful they are super easy to break. Next on my list would be clogged catylitic converter. But I would just cut them out entirely if you can in your area and put some good mufflers on it. I have a bunch of other things to try as well but I won't bore you with stuff that likely isn't the problem.
 
IIRC your car has a pretty significant amount of work/mods. I also believe you had a QH w Dalke tune. I've read a lot about the batteries failing or the QH otherwise losing the tune. The sudden on off nature of the start of your problem sounds like that is a good possibility. Might want to try reloading, or at least verifying that it hasn't defaulted to some sort of base tune (like back to the OEM, but is mechanically close enough for no load running).

Adam
 
one time i had no boost and car would barely go up hills otherwise idled fine and ran ok on the level .the balancer had spun making the spark plugs fire to late
 
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