Ok, this is for my buddy. He has a 2000 silverado 4x4 with 17x9 wheels, 37x12.50 tires, 6" suspension lift, 3" body lift, and 4.88 gears. The truck has 158k on it, and was stock for 150k. He bought the truck used at the 150k mark, and it is believed to be originial tranny and all.

Here's the problem. He says that when the truck shifts to OD and is around 1,000 rpm that it starts surging, rpms just jump up and down til it gets the revs on up. He asked me if I thought it could be the torque converter. He has a HPPIII and got the tires and the gears as close as possible to what they are, but I believe that he said it only went to 34" tires and 4.56 gears, but that's still better than the stock settings. I wonder if it is a bad converter or just needs some tuning like LS1edit or HPtuners?

He also wanted to know if he needed a new converter if the stock converter from my pewter car that I have lying around would work. I know it would be a bit higher stall speed and STR, but just curious. Help me to help him fellas, thanks.

 

Come on fellas, I know someone has an idea about this.

 

I have the same problem on my 2000 as does another member I found using the search feature. He has a 2000 as well. I did a post in another forum and got mixed responses. My truck surges 100-300 RPM in 1-2 second intervals and doesn't stop until 50mph. It only does it with the shifter in 3 or D. It's annoying as hell and I wish someone knew what causes it, so I'm bumping this post to the top. It doesn't do it in 2 so I'm pretty sure it has something to do with the TC (mine happens to be a Yank Truck 3000) Someone PLEASE help us.

 

Do you guys have a scan tool? Or maybe friend that has one...

If you think that it is the converter then monitor the TQ slip speed… pcm lockup command.
When the converter is locked you should see 2 or 3 rpm slip max…
It could be the lockup clutch

Also make sure the fluid level is right you might also want to do a complete fluid change.

 

does it surge at idle too?

 

No never at idle, only above 25mph when the verter locks up. The 3-4 comes at 45mph and the surging stops at 50mph. I'm about to talk to the dude that tuned me. I've done some research on this site and I'm almost positive this is "cam surge" even though I have the stock cam. I'm going to see about getting the lock up raised to 45 or 50. But guys, does the lock up HAVE to happen in 3rd gear?

 

Well this thread is getting some response finally. From what he says it's in OD when it does it. If someone figures it out please let us know. Thanks.

 

I'm going to put my lock up to 50 mph instead of 25. That should take care of it. GM probably fixed this in the 01+'s. I doubt this would happen to a stock truck though.