nickmak

Hey I posted this on another forum but I bet i'd have better luck here! i've been having rev fluctuation problems and an annoying hesitation when the engine is cold so I finally adjusted my TPS, adjusted my idle and timing and it runs GREAT now. Now my problem: cruising at 80+ on the highway and the engine is at approx. 2000rpm, if I let off the throttle completely and step on it again, the engine revs up to 2250rpm for a split second then back down to 2000rpm. Sorta like the transmission is slipping. This is only at highway speeds, with OD on or off. I don't know if it was doing this before I adjusted the TPS. Is the TPS not adjusted correctly? Transmission is on its way out? It was "drain and fill flush" a couple months ago and I put a new filter on it as well. Shifts fine all the time, never had any problems with it except for the AT temp light coming on briefly when wheeling awhile ago. Mind you the transmission has almost 360 000km's on it. Just not sure if this has anything to do with the TPS. Any help would be great, thanks!

vasinvictor

iTrader: (3)

Absolutely nothing to worry about. It's your torque converter unlocking and then locking back up. You can duplicate your symptom by cruising and very slightly tapping the brakes. That will unlocked your converter and then it will lock right back up.

And- you're running 2000rpm at 80+? I run ~3200 at 70mph with 4.88s and 31" tires. Bet your gas mileage is better than mine

nickmak

Thanks for the help!!! I was getting stressed!

I've got 31" tires and 4.88's too but mine revs at 2000rpm and 80 kmh (50 mph)! I'm in Canada hahah. So at 80 mph I'm sure I'd be around 3200rpm. Thanks again for the help!!

nickmak

sorry to bump an old thread, I didn't want to start a new one as my new "problem" is related to the torque converter locking/unlocking.

So yesterday I found a vacuum hose was cooked (accidentally routed it up against the EGR pipe) and was leaking. On the highway the torque converter wouldn't unlock and the truck would idle at around 1100rpm. I replaced the hose today and checked for vacuum leaks and everything seems fine. Except..

Before when I was doing 80km/h at 2000rpm and let off the throttle (briefly, as if I were approaching a slower car or something), the engine speed would drop to around 1750rpm. Once applying the throttle again, the engine speed would go up to 2400rpm then back to 2000rpm, that is the torque converter unlocking/locking up again. BUT now:

80kmh at 2000rpm like above. If I let off the throttle SLOWLY, the torque converter doesn't unlock. The revs drop slowly, as if the truck was standard and I was coasting in gear. But if I let off the throttle quickly, the torque converter unlocks, like above. Is this normal? It wasn't doing it before the vacuum leak happened, so I'm not sure.

Things I've done recently:
Replaced leaking vacuum hose and rechecked all hoses for vacuum leaks
Adjusted TPS again
Lubed throttle cable

Thanks!