The Problem: At WOT runs the car has problems on the 2-3 shift where it will seem to "stick" at about 6200 rpm, and just kind of "bucks" without going into the next gear and I have to let off the gas to allow it shift. It only seems to do this on the 2-3 shift as the 1-2 is smooth.
Under medium acceleration the shifts are excellent and no problems whatsoever.

Mods on the car are Shorty Headers, 3.73 gears, K&N CAI, Hooker Catback, SLP Speedo Recalb. and a lt4 KM.

The PCM has never been retuned after the mods have been put in.

Would a PCM tune for different shiftpoints and or firmer shifts releave the car of the 2-3 "sticky shift" problem?

 

ur probably having some kinda of power loss that it cant reach the rpm's u set it to... it could be anything from bad wires to a clogged cat.

 

computer tune might do you the trick, I've heard of it fixing that problem before on the forums.

 

I am suspecting a tune would due it good, even if it didnt fix the shifting issue.

The car does not have a power issue as it pulls like a bat out of hell throughout the RPM range..

I have a vid of the Tach sticking uptop if anyone wants to host it.
its ~9.2 megs

 

Try the tune and keep us posted on what the outcome is.

-Mark

 

Can do!

-Craig

 

What did you have before the 3.73's?


I had 2.73's. Car never hit rev limiter before it shifted. Well I had some 3.73's put in. Went to the track to get a pass. Well the car would hit rev limiter before it shifted into 2nd. And did the same thing before it went into 3rd. So I go take it to a local shop. And have them edit the pcm.

Well they edited the gear ratio but didnt lower my shift points. So when I went back to the track it shifted fine into 2nd. But when I went to go into 3rd it did the same dam thing. Its the same thing your talking about. So Im editing my shiftpoints hopefully this weekend.

I was told that when you go from such a big leap of a gear, the whole shift tables need to be lowered. And it makes sense because the pcm makes the a4 shift based on mph not rpm.

 

Sometimes a slipping tranny can cause that... the RPM goes up as it slips but the car doesn't get the the MPH it needs to get to shift so you end up hitting the rev limiter. Hopefully that's not it

I'll move this to the Drivetrain forum for ya...

 

Just a follow up report on the issue.

It turned out the tranny was going bad, and the effect was the tranny not wanting to shift and slipping real bad in 3-4.

4th gear finally went out and it just free reved in 4th.

Thanks for all the input but it turned out to be a bad tranny.