92 Bonneville Tranny wont upshift until 3500+ RPM

[edwardengel]

I have a 92 Bonneville SSE 3800 V6. About 2 months ago the tranny suddenly started having shift problems. We were on the freeway driving when we got off I suddenly noticed that it wouldn't upshift until 3500+ RPM's were hit and overdrive no longer works and 1st also doesn't work unless I manually shift into it. I ahve check all fuses in both the fuse box and convenience center and nothing is wrong there. Also the electrical connection on the forward side of tranny is connected but makes no difference when I take it off and drive it. Fluid is also freshly changed any ideas would greatly appreciated. Thanks.

[maxwedge]

Welcome to AF. This is likely internal, either a failed internal part or a solenoid is bad, a full scan with a trans function scannner will look at issues that could cause this, without getting too technical here. Mean while check for vacuum at the vacuum modulator.

[HotZ28]

In addition, check the modulator vacuum line for the presence of trans fluid. You could also have a shift valve in the valve body sticking! How was the fluid changed, by flushing, or dropping the pan & filter change? As Max said, get a scan!

[wafrederick]

That one is a cable shift,the early 4T60 and another thing to check is the cable going to the transmission to the throttle body if it moves freely.Unhook it from the throttle body to make sure it moves freely.Also another thing to check if the governor is not sticking

[Jrs3800]

Originally Posted by wafrederick

That one is a cable shift,the early 4T60 and another thing to check is the cable going to the transmission to the throttle body if it moves freely.Unhook it from the throttle body to make sure it moves freely.Also another thing to check if the governor is not sticking

Are we going to go through this again?

The 1992 Bonneville SSE has a 4T60 E..... No TV cable at all on this unit.... On this unit the Modulator controls Line pressure or shift feel not shift timing...

Do check the Modulator and make sure its not leaking internally.. If there is any fluid in the Vac side of the Modulator it will have to be replaced..

All Pontiac Bonnevilles 1992-1997 NA Applications, and all 1992-1996 SC Applications are all 4T60 E...

The last Production year for the Bonneville to have a 4T60 was the 1991 Model year

[HotZ28]

Originally Posted by Jrs3800

Are we going to go through this again?

Wow, and yes it was only two months ago that we went through all this; Click Here

[wafrederick]

All I seen were cable shift transmissions in 1992 Bonnevilles and never seen a 4t60E in one

[Jrs3800]

The 440-T4( a.k.a 4T60 ) Looks almost identical to the 4T60-E...

This is a 4T60-E with its Guts spread out across the floor...




This one is for a Supercharged 3800...



As a complete assembly...



The only item I need to know exactly what trans the guy has in his 92 Bonneville is the Trans Tag ID...

But just for sake I do have the 1992 Bonneville ( H Body ) Factory Service manual... 4T60-E was used on all of them weather it was a 3800 TPI or a 3800 SC...

Look around and you'll see people here trying to use 1992 H Body 4T60-E's in newer cars only to have issues due to wiring problems as the pin outs changed over the years..

Just keep in mind every H body 92+ used the 4T60-E, and every 91 C Body made used the 4T60-E as the 4T60 was being phased out...

Let me add... The delayed shift can be due to an unhappy solenoid, Low pump pressure, a Bad apply piston seal or possibly a valve body cross leak.... If the Modulator is absolutely shot it ca cause a low line pressure condition, this can cause a late shift if the pressure is dead low... So as stated before check and make sure the Modulator is good... Even an adjustable Modulator may buy you some time as you can turn up the modulator to get a bit more line pressure...

The best thing to do is to have a Tool hooked to the car while on a run and see what the PCM is doing when the problem occurs, also look to see what the Slip RPM's are when the TCC is on and the PWM is at 100% Duty Cycle... 0-10 Rpms would be normal... 20-30 wouldn't be a killer... If there is too much slip when the TCC is applied and the PWM is commanded 100% the PCM will default and not allow TCC apply iirc untill the next drive cycle only to have the problem repeat...

Not sure if there is much more that can be answered betond this without knowing what the PCM is seeing and doing...

OP, if you have any questions please ask