joecar

What RPM's in 2nd gear and 3rd gear do those WOT shift point MPH's correspond to...?


RPM = MPH * 336 * GR / TD

where:
GR = trans ratio * axle ratio
TD = tire diameter (inches)

joecar

Make WOT upshift MPH achieveable (i.e. RPM can be achieved without hitting limiter).

Make WOT downshift MPH at least 5 MPH lower than the upshift.

Are you seeing any DTC's...?

Reserector

Reserector

I'll try to raise the upshift.
No codes.

joecar

I fixed the strange characters that my phone had inserted:

joecar

2->3 upshift MPH 42.97 mph:
RPM = 42.97 * 336 * 4.63 * 1.625 / 34.7 = 3130 rpm

you can raise the 2->3 WOT upshift higher;
and also lower the 3->2 downshift a little
( the downshift must be below the upshift )

Reserector

I bumped the upshift to 66.97, and dropped the downshift to 59.97. That's 7 mph difference.
I also bumped the upshift rpm back up to 5200 because when it DOES shift ( during passing) it happens too soon.

Then I got out on the interstate and nailed it. 1-2, great. 2-3 went to the rev limiter again.

I keep thinking that second isn't releasing, which prevents third from engaging. Maybe when the new band wears a bit, it will magically start working properly.

Any thoughts on the low-ish pressure?

joecar

Set the RPM to 4000 and try this again.

Where are you measuring pressure.

Reserector

I'll give that a try.
I'm measuring pressure with a gauge, tapped into the port on the side.

joecar

If pressure is low, this indicates that the pressure regulator is worn (the valve wears the bore), this also means the trans slips, this is one of the causes for missed WOT upshift.

What does pressure gauge show when idling in R, N, D...?

What does it show at WOT...?

mrvedit

I'm curious what the line pressure is during the 2->3 shift.
Running only 50 psi is Reverse is strange - the reverse circuit moves the boost valve into a higher pressure position. Makes me wonder if the boost valve is sticking or has a significant leak. I suggest installing the Sonnax 4L60E-LB1 (or LB2 for 2006+) into every rebuild or even stock unit. It increases line pressure across the board and it;s o-rings prevent leaks.
A sticking valve in the VB could be the culprit but i don't recall a single thread where that was the cause.

Reserector

i used a reman pump that came with a boost valve measuring .50 so I assume it is a transgo.
I'm not opposed to replacing it with the sonnax part.
I'll order one. I have a feeling I'll be pulling the pan soon to poke around. Might as well at least do something that "can't hurt".

@joecar. When it should be shifting, the pressure is high. Like around 200. But as soon as I get the ac back together, I'll go for a drive and see exactly what it is reading at that moment.
Now, if this rain will just let up...

Reserector

Boost valve is ordered.
Another thing I've noticed, that might be pressure related, is a slight pulsing around 35 when I'm just poking along, and it's locking up the converter. It never did that before the rebuild, and it doesn't set a code.
Wondering if I should pull the VB and update the TCC valve while I'm in there. I'm open to suggestions. It just seems strange that it only started this after the rebuild.
when it is pulsing, pressure is around 100-125. It only varies about 5 psi, and is not jerky.

​​​​​

Reserector

Idling in p,n,r,d it holds steady at 50
At wot, it's at 160, but just after a shift, it jumps up to 220 for a moment.

​​​​​​Interestingly, when it failed to do the wot 2-3, it still jumped up to 220 as of it had.

Reserector

Correction:. I watched the gauge when I started it this morning. I shifted into reverse, and after a couple seconds, it rose to 90. I checked later, after it was warm, and it would go to 70 in reverse.
Bypassing somewhere? Boost valve is my guess.

I know for a fact that it has the pump screen and it's o-ring that is sometimes left out, causing a bypass. It's not that.

hfthe3rd

iTrader: (1)

I just joined this club after hitting the dyno.

Reserector

hfthe3rd

iTrader: (1)

I just recently did a cam swap and while my car was being tuned the second gear went and wouldn't shift into third unless you let off the gas.

mrvedit

The combination of a worn transmission, more engine power and your desire to enjoy the power probably worn down the band.
Engine upgrades should be combined with transmission upgrades such as a shift kit or even overhaul if the miles are high.

joecar

This is a slightly different/additional problem if you lost 2nd gear.