48RE Line pressure goes crazy

[Ozymandias]

I've an acute problem here.
Since today I see crazy high line pressures above 400psi (gauge maxes out at 400psi).
Yes, 400psi+ that's right.

What happens..

It does not matter which gear the transmission is in, 1,2,D or Lock-up all the same.
I correlates strictly to throttle position, the more throttle the higher it is.
Cruising down a flat road with 55mph I see like the usual 140-150 psi, as soon a it comes to an incline (more power needed) the pressure raises all the way up behind the scale of the gauge. If I let go the throttle it comes down.
If I play with the throttle the pressure does accordingly.

Another notice, if I'm in 2nd gear, go into the throttle, it stays for a second at the normal pressure level and then it just jumps up to the beyond 400 mark, like it was hold back and then something loosened up and let it go.

I noticed delayed upshift under hard acceleration but that's about it, without that gauge I think I wouldn't even have noticed that problem.

Has someone here a clue what is wrong with that transmission?

transmission has a Transgo Shift kit in it, a GM solenoid and a Rostra HD Transducer, everything worked fine for the last 100K. Trans is regularly maintained with oil change and band adjustments.

Thanks in advance

 

[AH64ID]

Are you sure the gauge is reading correctly?

 

[Ozymandias]

Are you sure the gauge is reading correctly?

99% yes, it seems reasonable what it shows me as cruising down the road it shows like always before, maybe a tad higher.

Tomorrow I'm doing a test ride with AutoEnginuity to check the return and commands from transducer and solenoid.

 

[Ozymandias]

Follow up here even without an answer.

I hooked up AE today and monitored what was going on during the drive

There are three PID for the transmission.
Desired Governor Pressure
Actually Governor Pressure
Governor PWM

All three work together - as long as Desired GP stays below 85 PSI.

As soon as that value is demanded above, let's say TCC is applied that demands 127 PSI, the Governor PWM drops down to one, means fully open circuit and my manual Gauge goes Crazy.
But the Actual measured stays at around 89 PSI without reaching desired 127 PSI.

Means, Pressure Transducer is bad.

I now drive with the TV Cable disconnected as that way actually pressure maxes out at around 100 PSI, no matter how much throttle is applied. Off course the shift pattern is bad that way but at least I can drive without blowing out seals or do any other harm to the Transmission.

Maybe that thread helps someone else with the same problem.

 

[Ozymandias]

Back on field one, I replaced the pressure transducer for good. The problem persists.

And just FYI, it is incredible hard to get either parts or a workshop that has time.
All seems to booked out for weeks to come or lack parts for weeks to come.
Really really bad.
Being in the Vancouver/Seattle Area, I'm open for recommendations.

Thanks

 

[AH64ID]

That’s too bad, with that high of a reading I was really thinking pressure transducer.

 

[Ozymandias]

Me too, especially because of the difference between command and return. I'm somewhat stumped now.
Also because Googleing for "to high line pressure" returns - guess what - Zero results.

Tomorrow I'm going to a very small Trans shop here in Williams Lake to hear what they say about it and maybe proof that the readings of my gauge are right or wrong.

 

[endoscott]

Rairdon dealership in Monroe, WA 360-805-5500, they do a ton of RAM trucks. Larry is a mechanic there who fixed my AC, many years experience, he would know who is good for transmissions in the area. One of the service writers is also very knowledgeable I think his name is Aaron, can't remember for sure.

 

[CVR222NV]

Ozy, I have a good friend that lives just East of Seattle and he has a friend who is a diesel mechanic and the transmission shop he recommends is Pac Trans Corp. out of Yakima, WA (509) 457-5005 which is 130 miles East of Seattle. Good luck.

 

[Ozymandias]

Thank you to everyone that has helped here so far, I see what I can do in the end.
I'm close to WA right now and there I have a friend with a decent workshop, so I'm going to work on it myself and see what I can do. Think I maybe have a sticky valve or broken spring in the Valvebody.

 

[Ozymandias]

Okay, being back in the lower forty eight gave me the chance to buy a transmission pressure gauge kit for a decent price...

Hooked it up, and guess what - my expensive German made VDO gauge/ sender is bad!
All pressures are perfectly in range for a VB with a Transgo Kit in it.
I feel so ****** about that.

Probably some of you think "why didn't he check that earlier?"
Well, like said no workshop wanted to work on it without waiting for two weeks, and, the cheapest gauge in Canada NAPA was 160$! that I wasn't willing to spend as here I paid 20$ for the same unit which is reasonable.

Thanks everyone for helping me here.

Oz