Torque Converter?

bassadict69 · March 24, 2008

When driving at a steady speed, usually 35-55 mph, my rpms will surge by a couple hundred rpm...someone said it may be my torque converter locking & unlocking. Is that what it sounds like?

There is no power or speed change with this & it does it on smooth road regardless of bumps or not. I have noticed I can almost make it do it every time if I let off the accelerator just a **** hair!

Is that a bad sign? It has been doing it a couple times a day for a while but lately has been doing it more & more. Is it normal?

Bish · March 25, 2008

Sounds like it is torque converter lockup. I believe it locks at 40 or 45mph I can't remember which. It annoyed me so much on my Tahoe I had a tuner bump it to 50. It should be consistent though. Meaning there should be no change in behavior over time. Mine got a lot worse when I had the trans built and put in an aftermarker converter but again I had my tuner raise it.

redvett · March 25, 2008

Your tire size has some effect on TCC operation. Have you had your PCM speed input corrected for the larger tires? If not do that first.

bassadict69 · March 25, 2008

Yes, the PCM has been tuned & adjusted for the tires.

I just got the tune & have had the problem LONG before getting it! I even went as far as to put my stock PCM back into the truck to make sure & the problem was still there just as much as with the tune so I know the tune has nothing to do with this.

So, this is normal?

Zembonez · March 25, 2008

So, this is normal?

Mine does the same thing but at a little higher speed. I think it is normal TC lockup and nothing to worry over. I can see it on my tach but I can't actually feel it doing it most of the time.

hoorders · March 25, 2008

When driving at a steady speed, usually 35-55 mph, my rpms will surge by a couple hundred rpm...someone said it may be my torque converter locking & unlocking. Is that what it sounds like?

There is no power or speed change with this & it does it on smooth road regardless of bumps or not. I have noticed I can almost make it do it every time if I let off the accelerator just a **** hair!

Is that a bad sign? It has been doing it a couple times a day for a while but lately has been doing it more & more. Is it normal?

My truck was doing the exact same thing for more than a year......then I took it in to get the tranny pan dropped, fluid change and filter......the shop called me and said i better go an have alook before they do the service......the pan had LOTS of metal filings in it........Figured with the milage on my truck and im going to be pulling a 5000lbs trailer this summer, I might as well rebuild it.....once they pulled it apart, the torque converter was burnt purple from engaging and disengaging...with the new tranny...its shifting amazing......like driving a new truck........

need-for-speed · March 25, 2008

When driving at a steady speed, usually 35-55 mph, my rpms will surge by a couple hundred rpm...someone said it may be my torque converter locking & unlocking. Is that what it sounds like?

There is no power or speed change with this & it does it on smooth road regardless of bumps or not. I have noticed I can almost make it do it every time if I let off the accelerator just a **** hair!

Is that a bad sign? It has been doing it a couple times a day for a while but lately has been doing it more & more. Is it normal?

How many miles do you have on it? The clutch material in the torque convertor wears too.

wlvrn1215 · March 25, 2008

mine does the same thing ....at least im not going crazy.

bassadict69 · March 25, 2008

Truck has about 97000 miles on it.

Truck is going for a filter & flush today so we will see if any shavings are present.

bassadict69 · March 25, 2008

So, this is normal?

Mine does the same thing but at a little higher speed. I think it is normal TC lockup and nothing to worry over. I can see it on my tach but I can't actually feel it doing it most of the time.

That is exactly like mine...if I couldn't hear it in the exhaust & see it on the tach, I would never know it was doing it...you cannot feel anything!

bassadict69 · March 27, 2008

I have 98000 miles on the truck & I am leaving tomorrow on a 2 1/2 trip towing my boat so I took the truck in for a flush & filter change. I asked about this & they said it is normal & some truck seem to do it more than others & it even did it on the road test before they did the work...they agreed it is normal.

After dropping the pan, the owner of the place came out where I was waiting outside...I thought for sure they had found problems! First thing that crossed my mind was one of the earlier posts here. But, he said everything looked REALLY good for the mileage & the fact that I do quite a bit of towing. He said there was no metal in the pan & the fluid looked good!

I have done quite a bit of running around town since the service & it hasn't done it at all since the service! Not sure why...but works for me!!

need-for-speed · March 27, 2008

I have 98000 miles on the truck & I am leaving tomorrow on a 2 1/2 trip towing my boat so I took the truck in for a flush & filter change. I asked about this & they said it is normal & some truck seem to do it more than others & it even did it on the road test before they did the work...they agreed it is normal.

After dropping the pan, the owner of the place came out where I was waiting outside...I thought for sure they had found problems! First thing that crossed my mind was one of the earlier posts here. But, he said everything looked REALLY good for the mileage & the fact that I do quite a bit of towing. He said there was no metal in the pan & the fluid looked good!

I have done quite a bit of running around town since the service & it hasn't done it at all since the service! Not sure why...but works for me!!

Excellent.

hoorders · March 27, 2008

I have 98000 miles on the truck & I am leaving tomorrow on a 2 1/2 trip towing my boat so I took the truck in for a flush & filter change. I asked about this & they said it is normal & some truck seem to do it more than others & it even did it on the road test before they did the work...they agreed it is normal.

After dropping the pan, the owner of the place came out where I was waiting outside...I thought for sure they had found problems! First thing that crossed my mind was one of the earlier posts here. But, he said everything looked REALLY good for the mileage & the fact that I do quite a bit of towing. He said there was no metal in the pan & the fluid looked good!

I have done quite a bit of running around town since the service & it hasn't done it at all since the service! Not sure why...but works for me!!

Good stuff!