First, my truck isn't completely stock (might be the problem?) see signature below.


I only drive my truck but about 2-3 days a week. Over the last two months I've had this problem happen 6 times out of about 50 cold starts. (not ambient temp cold, just engine cold) When I start up and take off slow, it feels like I'm starting in 4th'ish gear. If I keep the revs low it will slowly increase speed. (It feels like if you were driving a standard and starting in forth and riding the clutch to slowly get it up to speed.) If I press down on the accelerator the revs will go up quickly as if I was in neutral and then slam into gear with a hard clunk as a result in the rearend.


Has anyone else had this happen? BTW I've done nothing different recently to the truck and 90% of the time it starts and shifts perfect. It's just a roll of the dice whether it will happen.


Maybe it's the tune? Maybe I should change the tune? Any help would be appreciated, thanks.

 

Did the problem happen after the tune? Or did the problem just start out of nowhere?

 

I tuned it about 3 years ago. I have gone back and forth in the past but have been running the same tune for the last year at least with no changes.

 

Any servicing done? Possible you had the transmission fluid changed?

 

Nothing at all done over the past year.

 

I know our transmissions have a learning feature to adapt to the way we drive, possibly resetting this could help. I'd also try stock tunes for a while

 

With my mods the return to stock tune runs like s*#$. I'll try going to stock, then going back and see what happens. Basically resetting it.

 

Yeah I remember mine felt like that once or twice, I had the loud shift bang noise between 2 and 3

 

Ok, it's getting more and more frequent now. It's not only happening at startup anymore either. If I leave it running in park it might happen also after putting it in drive.

And 3 times at cruising speed the wrench came on and downshifted, it seemed like it went into safe mode.

A new thing I noticed, every time this happens the speedo goes to zero.

To clarify the original issue the truck felt like it was in neutral but now I can see its in 5th gear from a roll and will rev up like in neutral if I let it, then it will slam into a lower gear like 2nd. It seems like it doesn't know how fast the RPMs are, or the trans rotating. Is there a sensor to check?

Really could use some advice here.

 

Have you tried resetting your computer yet?