I seem to be having an issue with my TC. Driving down flat roads with the cruise on, my RPM's will jump up 2-300 stay there for a few seconds, the go back down, like its locking up. There isn't really any rhyme or reason, it will do it with o/d on or off. I'm hoping a complete fluid change will help out, since I have no idea when the last time it was done, if ever? Is there anything else that could be the issue? Maybe something electrical? Vacuum line maybe? Or am I gonna need a new TC?

BTW, my dad put 255/70's on the truck about a year ago, I don't know if it makes any difference given that its not much of a difference over the stock 235/70's, just thought it might make a difference.

 

I would get an idea from the trans shop as to the exact problem. Possibly a valve body damage problem or servo. I take it it works perfectly except for the occassional increase of 300 RPM's? How about with the cruise off? Does it work perfectly than.

 

Yeah, works great the rest of the time, it will do it with the cruise off, but I set the cruise if I'm going more than a mile it accelerates good, downshifts fine, the fluid does need changed, but it doesn't smell awful, just a little burnt.

 

OK you got it. Will a change of fluid and filter fix it? Sounds like slippage is take N Er away from you soon. Tis a cheep thing fluid and a filter, possibly dropping the valve and cleaning it out. Compared to a rebuild swap I's say. A lot of metal filings and brass in the trany pan, will lead to the answer you seek.

 

That didn't make my day but thanks for the info papa, I'll get that pan dropped and
See what kind of trouble I'm in.

 

Good, I would expect a broken part in the valve body/solenoid possibly if you have little debris in the pan.

 

How tough is a valve body replacement? I know guys are
Changing them out for performance ones, seems like it would be fairly simple with a bit of instruction?

 

Before you do anything check your trouble codes for a trans related code. It will pinpoint an electronic fault. Your PCM does a lot of measurements from accelerator positon and throttle body opening etc.
Torque Converter Clutch Solenoid
Torque Converter Clutch (TCC) solenoid receives a signal from PCM. TCC solenoid controls application and
release of torque converter clutch. If solenoid fails in ON position, engine will run rough (shudder) and engine
stalls in Drive at idle, low speeds with brake applied, or in manual 2nd gear. If solenoid fails in OFF position,
torque converter clutch will not engage. Transmission Control Indicator Light (TCIL) may flash. On gasoline
engines, an On/Off TCC is used.

 

I had it checked a couple weeks ago for a CEL, it's my fuel pressure sensor, that's the only codes I have. This has been going on for awhile, it hasn't gotten worse, somedays it's better, which kind of had me thinking it might have something to do with the TC, it's not a slip, it isn't a quick snappy rev like the engine just became unloaded. It goes up a few
Hundred, then holds for a few seconds, then goes back down which is why I figured it was a TC issue, honestly, the transmission shifts nice and solid, there's no noises, no delays, works great, even a full throttle run turns out pleasing results, it's just when your cruising at a steady speed. It's almost I'm getting a pressure fluctuation causing partial TC lockup, full lock up is around 2300 RPM's at 60 mph, mines going to 2000, and I'm not losing speed, but if I accelerate gently when it does it it will fully lock up?

 

OK a PSI test and pull the pan would be good. Debris in the oil will mess thing up good, and low oil psi is worse. Right now I'm leaning toward the TC clutch as malfing. It just won't quit for a while.

TORQUE CONVERTOR ENGAGEMENT TEST
Connect tachometer to engine. Ensure engine and transmission are at normal operating temperature. Drive
vehicle at about 50 MPH in "D" position (overdrive on). After normal operating temperature has been reached,
maintain a constant speed of about 50 MPH and tap brake pedal lightly. Engine RPM should increase when
brake pedal is tapped (TCC disengages). Engine RPM should decrease in about 5 seconds (TCC engages). Slow
to a stop. If TCC does not engage during road test or is engaged continuously (causing engine to stall at stops)

 

Ok, I'm going to reset the PCM tonight, drive to work and back tomorrow, about 45 miles round trip, then have my codes checked again, I didn't think about it before
But I reset it the last time so I didn't get a bunch of false codes. I'll do the TC engagement test on the way home. I'll probably have to wait until next weekend to drop the pan so I've got a little extra cash to get fluid and a filter while I'm in there snooping around. Thanks for the help papa, that's a wealth of info, I'll be saving that for future
Reference.

 

Good, don't know your temps, it all may come down to rolling resistance of cool weather? Look at your tires air PSI and of course fluid, filter and oil PSI along with other maintenence. Mine shifts 6 times so, it constantly is shifting and adapting to the pedal positions. With the adaptive PCM strategy it takes a while to relearn my driving hapits and gets better with tow/haul selection over time.

 

I had a thought (scary, I know) I went out to my moms place this afternoon, I tried the engagement test on the way out there, it worked, in fact, it did just what the truck does when the rpms are jumping. So I got to thinking maybe I've got something causing resistance? Tires are good, I just checked them this morning, so I was thinking what if its a brake hanging up? Then I checked out my rims, there's brown dust all over the front right
Wheel??? Sounds like I might have a caliper hanging up on me. Does that sound feasible to you papa?

BTW, temps here are cooler, low 30's in the morning 50's-60's in the afternoons, doesn't seem to make much of a difference though.

 

I would def check for the hang up. Usually a squeel from the worn pad or a pull is noticable in the direction of the drag even the rotor so rough it catches your finger nails. But a wheel bearing is also in the mix. Or the malf is a brake light pressure sensor going they do double duty with the cruise control also.

One thing that happens is the dust boots on the piston cut in the calipers and dirt/grime get down in there causing the brakes to hang and drag the pads. You have to take it all apart to find the damaged dust boots. If you have a infrared scanner the heated rotor will show up after a hard run. At that point new calipers/pads and possibly rotors is best I think. You may be in the beginning stage of the problem? It will rapidly get worse usually.

 

Ok papa, check this out, I drive the truck to work this morning, about 22 miles, all 55 mph highway except for a couple small towns where the speed limit drops to 45. So I did my very best not to use the brakes and just down shift and let the engine do the slowing down and it didn't do it once this morning... I'm still going to do the fluid and filter
Change this weekend, it needs it regardless, but I guess I'll be checking my brakes out while I'm at it!