Some of you may remember I have been having an issue in mid-high boost (10-15psi) at high RPMs. First it was a wastegate issue resulting in overboost and a lean condition. That has been fixed. Then I perhaps thought it was spark blow out. Swapped in the 2.2 coil conversion, new coils, plugs, and wires. It doesn't sound as odd anymore, but now the issue seems to be that the tranny isn't shifting soon enough and I end up bouncing off the rev limiter. It sounds just like that now, whereas before the coil swap it was more of a popping sound. The tranny is a 4T40e. B&M shift plus is installed, but after logging I realized it only would raise the line pressure to 35% when on the high setting. With it off, the tranny automatically raises it to 35% under high load. So anyways, I have the tune set to have the tranny shift at 4750rpm. Going out for a quick run, it still continues and you can see by the log that its not shifting at that point. Tranny seems flawless under any circumstance other than boost above 10psi. Any ideas on how to fix my current predicament? Here's a pic of a log showing when it acts up. I'm not sure if its the tune and/or timing issue or the tranny. Torque management is still on stock SC reflash settings, perhaps its cutting too much timing and that's the issue? Thoughts? (Log shows current trans gear as well all other needed info)






12.6 @ 114.6 MPH

Put the tranny settings back to stock and try it. What does it do?

It has been found when tuning the auto tranny a lot of time and patience is needed. The auto tranny has many settings that need to be change together.

example you have shift RPM's, but also shift speed. You can not change one without the other. You also need to make small changes on these.



FU Tuning

I believe it was doing it when the settings were stock. The only thing I changed was the "full throttle shift RPM" for both "hot" and "normal". I was under the impression that those setting would be the maximum allowable RPM before the tranny shifted. I didn't think you needed to change the speed as well because I didn't think it would refuse to shift unless both criteria (speed and RPM) were met if its past its set RPM, but not speed? In that case it would always bounce off the rev limiter if the speed was set too high per gear. Bet I guess perhaps I was wrong. In my log, I wasn't up to the speed set for it to shift into 3rd yet, but the RPM was met. So maybe it is that simple. I'm curious though, if that is the case and both RPM and speed need to be met in order for it to shift at WOT, wouldn't it vary greatly, even stock, if you floor it from a stop vs flooring it from say 60mph? By vary greatly, I mean it seems like there would be certain conditions were it wouldn't shift and bounce off the rev limiter even stock, no?



12.6 @ 114.6 MPH

Step one... Take the damn B&M OUT!

Not just off, get it out of there... There is no reason you should be using it if you have HPT.

Since your built, I would change the rev limiter as well, bump it up another 500rpm and see if it shifts properly. Then at least you know the threshold you should shoot for.



Buildin' n' Boostin for 08' - Alex Richards

turn the traction control settings to maximum.

enjoy.



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