So this transmission has been in my car for about 7 years, behind only about 450 RWHP. Its been perfect. But about 3 months ago, every now and then while starting from a traffic light or stop sign and accelerating casually, not aggressive at all, first gear will hang longer than normal slowly climbing up to about 3800 rpm and then shift into 2nd. From there on its all normal shifting in all other gears. Then for a week it might not do it again. Then, it will happen again and maybe do it a couple times in a couple days. Then not for a few days again. When its not doing it, the transmission is shifting completely normal and strong. If I get on it hard it never does that, it shifts through all gears normally.

Tuning issue or mechanical? Something wearing out?

Just strange that it comes and goes......

Thanks.

 

With s come and go. I would take a look at 1st the data if possible to see if it is being commanded to do that or commanded normally and doing that.
I say this because you can have intermittent issues related to sensors etc. that might not set a code.(example my car randomly idles itself up from 650 to 1000 rpm and I have yet been able to figure out , no codes nothing)
Assuming its not commanding that issue I would look at shift solenoid A, The 1-2 shift valve and spring I have seen the spring break and most rebuild kits come with one in them to replace it.

 

Im waiting for my tuner to get back to me to see if he can see anything.

But if that spring is broken wouldn’t it do that long hanging 1-2 shift every single time I begin to accelerate from a stop?

Can all three possibilities you mentioned be taken care of by just dropping the fluid pan?

 

The spring can also just become weak but also they is a low pressure signal behind the valve on the spring side pushing , So yes could still work with broken spring intermittently .
Repair and verification would require VB removal and this can be done in truck . Note with the SOL remove can use an ice pick or similar to see how spring is doing as you can stoke the valve and the spring is pretty stiff actually.

 

Ideally, try purchasing or borrowing a 0-300Psi Hydraulic Pressure Gauge (and 6-8 feet of hose) so that the Line Pressure behavior can be monitored while driving.
Tape the Gauge to the Windshield so that you can both drive and see the Line Pressure reading.

Then hopefully you can see what happens to the Line Pressure while the Transmission is misbehaving.

You can tell us if it spikes or drops.

 

ok cool. Thanks for the info. My transmission guy is going to take it as soon as I’m back from a trip next week.

 

I wouldn’t know how to hook it up….lol

But maybe I’ll buy the stuff and see if my transmission guy wants to hook it up and look at that first.

thanks.