Power loss when shifting

[sir-blah]

Something is wrong with my car. When I take it out to the top of say first gear, slam it into second it loses power; then it gets up and goes again. The feeling is like when you let out on the clutch at too slow of a speed, it jerks for a sec then goes hard again. Its like the engine hiccups right as I let out of the clutch and hit the gas.

It totally destroyed my track times and on the dyno we haven't been able to reproduce it. It never fails on the street though. The gauges do not show a fuel pressure drop during the power skip. My EGT doesn't spike. The A/f stays between 11.2 and 11.7, and last but not least on my list of gauges, the boost goes up the second I let out the clutch.

Any ideas?

 

[ShelbyGuy]

sounds like you're bouncing it off the rev limiter or have the traction control on.

 

[Juiced46]

Powershift and it wont do it. My car does the same, its like a small hesitation between very fast and high RPM shifts. its not the limiter. i know exactly what you are talking about. For me the cure is to powershift the balls out of it.

 

[Crowley]

Mine does that as well. I thought it was because you are no longer at WOT and your boost falls off ... as soon as you shift and are at WOT again, full boost is back ....

Should the car not act like that?

thanks,
Crowley

 

[cobravenom39]

Originally posted by Crowley
Mine does that as well. I thought it was because you are no longer at WOT and your boost falls off ... as soon as you shift and are at WOT again, full boost is back ....

Should the car not act like that?

thanks,
Crowley

That is correct

 

[CountySoldier]

It sounds like its just the boost bypass valve. Its blocking the boost between shifts to keep the engine safe. Do the bypass mod and see if it still does it!

 

[Jerryk]

Yep, your hitting the factory boost bypass, which is trying to limit max torque during a shift to try and preserve the tranny. Our tranny is strong and if you learn to powershift, the hesitation is eliminated and LS1's fall to the wayside. You can try the lesser solution of rerouting vacuum lines etc to eliminate the computers ability to dump boost but I'd rather leave it factory stock in that area and learn to drive it right.

 

[PhillyCobra]

Stock computer also has "torque management" programmed in, which cuts timing when you let up on accelerator. This can be programmed out with a chip or ECU reprogram. If you power shift, though, this is not activated.

 

[Emmerson_Biggins]

Philly is correct, it is torque management strategy programed in the PCM. In the cobras it can take away boost, timing, or both during an upshift.

 

[707RIDAH]

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?

 

[707RIDAH]

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Damn! I had the same problem with my car in second and especially in third. I thought I was just a bad driver or somthing was wrong with my car. So what you guys are saying is I can get this torque managment deleted out correct? Cause I am not too good at powershifting

 

[vipergts281]

My car has being doing this lately. Mostly on the 2-3 shift.

When I hit the gas, the car just falls on it's face....like someone else mentioned, it feels like when you let off the clutch too early and the cars jerks and then goes.