Lock Up Torque Converter

[thebandnerd03]

Ok i have done some looking around on the site and cant find anything on this. I have a 89 ld2500 with the 350 and a "4speed" 700R4. now i know 4th gear is actualy just the torque converter locking up for overdrive but why would this cause the truck to run rough. if i stick it in drive i have no issues with it. In overdrive if i try to hold speed around 45 it runns really rough and struggles untill i giv it gas or back off to less then 40. any ideas?

[scott473]

I have a 1500 same year motor and transmission, same problem too. I know mine has 2 issues, the 02 sensor is broken and the plugs need to be changed. Don't know if that's the problem but I'm sure they don't help.

[HawkScot]

Actually, the 700R4 has a 4th gear, an overdrive gear. It also has the lockup torque converter.

[DwayneJ]

Look for an ignition problem.

 

Might change the fuel filter and check the pressure but my money is on ignition.

[thebandnerd03]

i have already changed all filters and ignition components. even had it scanned by 2 different shops. any other ideas people might have?

[mjlimo82]

My Grandpa's 96 Chevy does this same "shuddering", if you will, when the torque converter locks up. I've had people ask me who've ridden in it why it "misses" when it gets up to speed, but it's actually the lockup trying to die. That might be the case with yours... although maybe not because this truck is a 4L60-E and it might be a little different in the way it works compared to the old 700.

 

This whole truck is about dead... 300K miles on the clock, the trans has been slipping for three years (Lucas is holding it together), it dies on occasion, the brakes go to the floor, front end's worn out... but he won't let it go. The old man loves his Chevrolet! I can't blame him. Engine's still like a new one - most of it's life has been spent burning propane, so it's as clean as a gas burner with 30K.