89 Olds 3rd Gear Lockup happening at 47mph

[redmetrix]

I am driving an 89 Olds with the 2.84 fdr and the 3rd gear lock up does not happen until 47 mph even under light throttle. Then the 4th gear lockup happens at about 50 mph which is normal. I have driven similar cars and the 3rd gear lockup usually happens right around 35mph. Is this how the 89 was designed to work? Is this something that is adjustable?

[Jrs3800]

Thats odd...

In general its designed to hit TCC apply at 35-36 Mph with light load... Now the question would be does the ECM see the 3rd gear switch when it should and how do the TPS values look?

[redmetrix]

The car also does seem to idle a little fast on a cold start (not too far from normal) so I wonder if it is related to the TPS...

Also the 4th gear lockup will sometimes happen anywhere from 48 to about 54 mph which I still consider normal. It doesn't help that it's so cold in Wisconsin this time of year, we've had single digit temps quite a bit lately, occasionally below 0.

I do have a factory service manual for my 90 Grand Prix so that might help me trouble shoot at well, same transmission I believe.

[rustyroger]

Back in the '60s British Borg warner 35 & 65 equipped cars would be reluctant to change up if it was very cold. I mean high teens, remember where I live!.

Maybe it's simply the intense cold that is causing your issues?.

Roger.

[RJolly87]

Back in the '60s British Borg warner 35 & 65 equipped cars would be reluctant to change up if it was very cold. I mean high teens, remember where I live!.

Maybe it's simply the intense cold that is causing your issues?.

Roger.

Maybe, but I would think the cold just affects whether or not it locks up, not when it locks up.

If the engine temp is too low, it won't lock up at all.

[Jrs3800]

The THM440-T4 and the ECM in the 88-91 Vin C 3800 are a bit on the dumb side... It simply looks to see if the engine coolant is at 120F and looks at load and road speed as well as the 3rd and 4th gear switches.. It generally need to hit 50 to shift into Overdrive... But once its in overdrive the trans may stay there until 45-46 and can hit TCC lock in 4th again at 45-46... The 3800 even then had enough guts to turn it at low Rpms...

It could be having a TPS related issue, or the ECM may be going between open and closed loop if its not warming up enough..

Also need to know if that 3rd gear switch is happy..

[redmetrix]

What do I need to do to know if the ECM sees the 3rd gear switch?

[Jrs3800]

Yeah it should see the 3rd gear switch, when it shifts to 3rd the tool should say something like ( 3rd Gear Switch = On )

If the car is warm it should hit TCC lock at 35-36 mph...