Thread: Quick WOT Run Question

I'm asking this to settle my nerves. First off, I know my trans is about gone if not already (after this run I heard whining and a bit of knocking in gear). Mods are in my sig.

I swapped to a 3.2 pulley and went for a test run. I drove around to get the car warm before I opened it up. Aeroforce was scanning for KR and LTFT. Once warm, from a 40 - 45 MPH roll I went WOT. Car down shifted and pulled hard. Car tried to shift up at ~103MPH. Trans slipped enough to let me bounce off the rev limiter. I let out.

What happened, I saw about 12 psi boost, 0 KR throughout the RPM range during the pull, LTFT's were 0 throughout the pull. When the trans went to shift up and it slipped I saw .6 - 1.7 KR as it slipped and hit the rev limiter I instantly let out.

My question, I assume the KR was due to the slipping of the trans since it was 0 throughout the RPM range during the pull?

id have to think hitting the rev limiter could cause a bit of KR.

plus what ever vibrations the trans was putting out when it slipped.

That's my thinking, I just wanted a sanity check and more opinions.

it also depends how your limiter is set. you can either have your fuel cut first or spark. if you cut fuel before spark you will go lean and see KR if you are cutting spark first then the Kr would be from the vibration instead. you should not hit your rev limiter during a shift either. either you are shifting too high or your limiter is set too low. always give your self about 250-300 rpm after the commanded shift as rpm's do climb until the shift is complete. so if you are shifting at 6,000 your limiter should be set at 6300.

also 103 is way to early to up-shift. you say your top swapped, so im assuming you have 3.29's. that would mean you were on the 3-4 shift.... you should never shift 3-4 at WOT. sounds like you need to remap your shift points up top.

This makes sense!!! Right now I am running an Intense custom tune so I have NO idea what my tune is set at or what it does. I sent John the specs of my build and he "tuned" accordingly. When the car tried to shift up it felt like it wanted to go then it felt like it went into neutral and at that time is when it bounced off the limiter. I do know John raised the shift points for the XP cam, but not for sure how much. I asked him to send me my .bin file because I have HPTuners on my computer, beta version, but no cable. John has yet to do that.

I am running my stock GT trans so yes 3.29's is correct. I thought it was 2nd - 3rd shift because when I run the car here at the drag strip, 1/8th mile, I leave the car in second and it is still pulling hard at the trap with 83 - 85mph speeds. I could be wrong...

I'd like to get into my tune and see what it is showing and share it with an experienced tuner to see if it's really a decent tune. I know it's running rich, probably washing a lot of the KR with fuel but I dunno...

yeah if someone is local and an tweak the tune that would be the best thing. 2nd gear will hit 6k rpm at around 90-95 mph. 103 would be way into the 6500-6800 rpm range if still in 2nd.

I'm glad you commented here, and I appreciate it!! These box tunes are for the birds... I wish I would have put the extra $100 with the cost of the tune and got HPTuners... I learned my lesson... LOL