KD93

Hey everyone. I was wondering if someone else had this problem. I get to 65mph, then the O/D turns itself off and I get a big old wail from the engine, and I loose speed 'cos 3rd can't handle the rpm's. I get to around 57 or 58, and it slips back in to O/D again.
I had the tranny rebuilt a while ago, and the guy got a valvebody kit and did that, but I don't know if he did it right or not . Does that even matter? Or is it more likely to be electronic, a sensor reading things wrong somewhere?
Any ideas and/or suggestions are appreciated. Thanks in advance.

93 12v

Might be TPS related.... Search the sticky for solutions.

jbix12v

someone i know is having the same problems. if you find out whats wrong with it then PM me what it was. thanks.

KD93

I'll do my best!

KD93

That's as good a place to start as any, although I don't think this is it. Will check when I get home. Thanks!

Crossy's son

Wire up a potentiometer so YOU can manually engage O/D.....

check the sticky for how to make a potentiometer controlled O/D or just buy the kit from a member named "DNRcustoms" ...i believe he gets like $20 for it.

i think theres a thread in the sticky on how to test the TPS

92smokin blacky

yeah try adjusting your tps, and if its shot, go with a POT controller, its cheap and easy.

bmpmoss

Got the same problem after I blew my trans lines. Tranny rebuilt 1 year ago Clean all contacts on senders that didn't help.Been driving it seems to be getting better.Going to check the tps when it gets warm.
Following this thread to see what others have to tell you.

KD93

Wire up a potentiometer so YOU can manually engage O/D.....

Hey Brandon,
I had the pot wired in before I had the work done on the tranny. Now I can control when O/D comes on, depending on how hard I dig my foot in. Anywhere from 30 to 55. So I took the pot out, 'cause I don't need it anymore. That's not the problem.
The problem is, when I'm lumbering along in the old beast, if I try to go faster than 65, it'll slip back in to 3rd. OWWWWW!!!! Not good. So, why does it do this? Mmmm.

Boatnik

Sounds like the TPS might be out of adjustment. If mine overtravels it will do the same thing. The tps can be very touchy when it comes to getting it right. At one end mines like you said. On the other end it will downshift when you let off the throttle.

Onemoparnut

I would also bet on the tps related problem mine did the same exact thing. I wired up a pot and it has been great ever since. there could be an adjustment issue or there could be a bad spot in the windings in the sensor. When it hits the bad spot it is kickin out of od. Just my .02

KD93

I slept on this one, and I was wondering why there would be a problem with the TPS at the top end of the rev/speed range. I don't have the answer for that, but I've got nothing to loose by putting the pot back in. Thanks for the help guys!

Keran

Rampage1967

You probably just have a worn out TPS. I replaced mine with one for a 3.0 V6 gasser a couple years ago. It's been working great since then & even kicks down to third at speeds below 55mph or so when I floor it.

KD93

I didn't get the chance to work on this today, as it was somewhere in the 30's and raining. I know I know, 30's ain't nuthin' to most of y'all, but here in South Florida it may as well be Antarctica, or Minnesota for that matter. Thing is, and I apologise for not mentioning this earlier, I replaced the TPS at the same time I had the work done on the 518, (at something like $150 from my friendly local Cummins shop, iirc! ) It's certainly possible it's faulty, but I sure hope not. In need of adjustment is much more likely, so hopefully tomorrow it'll stop raining at least. I'll let you all know how I get on, as it seems a few others are having the same problem.
Cheers, and stay warm out there!
Keran