three83

iTrader: (1)

Started having a strange issue with my truck. If I'm stopped or rolling 5 - 10mph and go WOT, it will start accelerating, then feels as if I lifted slightly and went back WOT (only does it sometimes). Also, if I take off normal, truck gets to say 25mph and is in 2nd gear, if I go WOT it take prob 2 - 3 seconds for it to downshift to 1st and start accelerating? (again only does it sometimes). It is like my truck just sits there for those few seconds then it is like "oh the driver went WOT, let me downshift to 1st and start accelerating." No check engine light or codes, using a handheld real time data tool it isn't showing knock retard, and Throttle Position is showing at 100% when these issues happen. I'm going to try to record some data with HPT VCM scanner to try to figure out what is going on. Right around the same time this started and brought my truck to an alignment shop to get an alignment. Battery was disconnected while alignment was done. I'm not sure if this is just a coincidence or if it has something to do with these issues. Anyone have any idea what might be causing this. It seems like Torque Management is doing this but Torque Management is turned off for the most part. I also thought it might be a sensor causing this but if it was a sensor seems it should through a code?

OLDPOS

my truck does the same thing when down shifting, seems to not know what to do. I started a post about this awile back and everybody told me my trans was slipping even though it isnt its just not down shifting quickly. hopefully somebody can figure this out and tell both of us!!

three83

iTrader: (1)

I spoke to a friend of mine that works at a GMC Dealership. I explained to him the issue I have and he said he had a few trucks come in with the same problem. He suggested cleaning the MAF and Throttle Body (allow engine to cool down before doing this.) Said a dirty MAF that isn't reading correctly but still operating in the normal range won't generate a code. After he told me this, I pulled off the Volant tube from the air box to the throttle body and removed the air filters. I can see that the MAF and Throttle Body are dirty. Prob due to the volant air scoop. Will report back the results.

three83

iTrader: (1)

Well, cleaning the MAF and Throttle Body seemed to help the downshift issue, but did not fix the launch issue. Went visit a friend of mine (Schexnayder Racing), pulled out the predator tune, tuned with HP Tuners and all is well.

Even in the heat (IAT were 100 - 104 degrees) and a 300lbs passenger my truck feels stronger than it ever has. I thought the predator with custom tune from Diablo Sports was close to as good as it gets, man was I wrong. I wish I would have done this a long time ago. Can't wait to go to the track. Then I'm selling the predator tomorrow for a $150.

OLDPOS

I didnt think that the maf would have any control over that but I will try it also and see what happins