Today I was 160 miles into a 250 mile drive and things were going well. I was cruising at about 75-80mph and approaching a fairly long hill of moderate grade. As I climbed the hill, my rpm was dropping, as expected before a downshift. The downshift never happened. I kept pushing more pedal and eventually, at maybe 40mph, it downshifted, but still no power. Engine being held at around 2500 rpm. No power no matter how much I pushed. Down hill I was able to resume speed but as soon as the next uphill, same thing, no power, no shift. Pulled over, it was raining hard. Checked for wet fuse box, control modules, pcm, wiring harnesses, everything dry. Checked all fuses. Disconnected battery in hopes of forcing reset, no change. Checked trans fluid, it was clean, red, full, and unburnt. No visual wires broken or chafed. No odd smells or sounds. Nothing noticeably hot. Truck hits 45mph max on flat ground. I limped it this way for 20 miles. If I push my foot to the floor to really force a downshift, engine will rev freely up to redline with no resistance once it downshifts. If I let the rpm drop down, it will catch and lock back in. Now when I come to a stop the truck has a very lopey and rough idle and will stall once I come to a complete stop. It will stay running if I give it gas. In neutral and park the engine still has a lopey idle and is rough. Will possibly die at times. Sounds smooth and perfect when you rev it in neutral or park. Reacts as it should with no hesitations. No check engine light and no flashing OD light. Will shift into all gears, just moves through them with no power. Let truck sit for 3 hours, issue remains.

Ideas?

 

What happens when you turn O/D off or put it in 1st or 2nd?

 

Acts the same.

 

I admittedly know next to nothing about transmissions...but a vacuum problem?

 

Sounds like the torque converter possibly...

 

That's no good, I think you have a fried transmission. Here's why:

Where in NH are you? I'm in Concord at the moment, but my AE is at home. If you're down south I may be able to come scan your truck this weekend.

 

Low fuel pressure/volume? kinda sounds like that.

 

Fuel pressure is 30psi at idle. Up to 40psi under full load. Stays consistent and steady based on load/throttle position.

 

I'm in kittery, me. Just over the border of portsmouth.

 

Since it's doing it through the range I'd also say it sounds like a torque converter issue. A TC is supposed to lock up allowing 1:1 drive and it sounds like it's having issues not locking up. It is possible there might be varnish build-up in the valvebody of the transmission. Has it every been serviced(filter cleaned?)

Transmission failures usually involve either TC failure or clutch pack slippage except for catestrophic failures like a shaft breaking in which case you're going no where. Since it is happening through the range it pretty much knocks out clutch issues because when it shifts through to a different clutch set it isn't engaging. Also, since you said the fluid isn't smelling burnt that is another indicator it's not clutches slipping.

It may be electronic in nature where a servo has gone out in the transmission, or it may be the TC itself. Take it to a trustworthy transmission shop and have them run diagnostics on it.

 

My thoughts are the same. No idea on trans service. I have only had the truck for a year and have not serviced the transmission, although the fluid looks great. PO was not big on maintenance so I doubt it has been done anytime recently.

I pulled the PCM today to check for moisture, none found. All wiring harnesses and fuse boxes are dry and clean.

Pricing out Transmissions now. If I am going to pull it to replace the TC, I will replace the whole trans with a rebuilt unit.

 

The engine sounds lopey and rough when in neutral or park ?
Sounds like it might not be the trans then ? Just a guess.

 

I was almost certain that yesterday it did. I may have to revise that comment though. Today I drove it and the truck was still lumpy in Drive when stopped at a stoplight but was smooth when I dropped it into Neutral.

 

Got it. Sounds like it might be the trans or torque convertor after all.

 

Are you saying when it downshifts it feels like it is neutral and then when you let off you can feel it go back into gear? If so it does sound like tranny but sometimes it can feel like that because there is simply no more rpm available. What is you manually put into a lower gear, does it feel normal?