What is this?

[greenhornet]

I have noticed on my 2000 Tahoe at approx.50 mph the torque converter will try to lock up which is normal and will drop about 500rpm when it does lock.

 

[LOUDHOE]

Yea,...I got it... Thanks for making it CLEARER for me....

No problem BRO!!!! Happy to help.

 

[toneman]

It may be the 4-5 gear solenoid in the tranny...

Unless I'm missing something here--and I don't proclaim to be a tranny expert...the OP's '03 Denali has a 5-speed tranny in it?

 

[ATL]

Maybe put the gear selector in 3rd, and drive at 50mph and remember the exact RPM's. Then put in OD and watch this fluctuation and try to determine if the transmission is really shifting down to 3rd or if the converter is locking and unlocking

i was thinking about this yesterday, and im not sure how much this would help, but maybe it can help narrow things down alittle. this video was shot at around 47 mph or so. when the video starts, i have the truck in 3rd gear, when it shifts, thats me putting it into drive. when it shifted into overdrive i was on a slight decline but once i got to flat ground, it started surging. considering it isnt going back into 3rd, maybe its just my converter locking and unlocking...???

 

[Vinniety]

i was thinking about this yesterday, and im not sure how much this would help, but maybe it can help narrow things down alittle. this video was shot at around 47 mph or so. when the video starts, i have the truck in 3rd gear, when it shifts, thats me putting it into drive. when it shifted into overdrive i was on a slight decline but once i got to flat ground, it started surging. considering it isnt going back into 3rd, maybe its just my converter locking and unlocking...???

ATL - of course just trying to give you some more ideas...but have you tried cleaning out your intake and mass air flow sensor? Unless your stuck in a gear lets say 3rd gear doing 10 miles an hour i don't see the surge issue being a tranny issue. I think you should start with the minor stuff like cleaning out your throttle body, intake and mass air flow sensor and go from there. Do you have an aftermarket tune on your truck? My fingers are crossed that's its not your tranny. Once again just giving some of my ideas i hope it works out for you!!

 

[ATL]

maf and tb have been cleaned multiple times in last 5k miles wondering if it had anything to do with it. the truck is stock with exception of k&n cai, and has not been tuned. but im 90% sure this is a converter issue. my stock trans went out around 96k or so. i had this one put in and the truck now has 180k on it. but this surging has happened randomly since i had the trans installed. of course it has started happening more often now that ive put 85k on the trans. i had to leave for work right after i got the truck back. when i came back i found that the warranty expired in time i was gone, but they checked it out for me anyways. left the truck with them(which is what i hate, and makes this so hard, i gotta have my truck) and when i came back to get it, they said they found a small leak in a cooler line. they charged me like $25 in fluid, and sent me home. the truck was still surging on the way home. but i figured if theyd charge me for fluid, theyll be more than happy to charge me big bucks if i bring it back again. so i just lived with it, thinkin id find someone i trusted to take a look at it, which never happened

 

[01Konvict]

Mine does the same thing and I think its with the converter. I just avoid it by going faster or slower, its just a weird spot where the TQ converter taking the load. Buy a higher stall converter and I bet it will go away.

 

[ATL]

Mine does the same thing and I think its with the converter. I just avoid it by going faster or slower, its just a weird spot where the TQ converter taking the load. Buy a higher stall converter and I bet it will go away.

interesting that your truck has been tuned but still does same thing. ive had multiple people mention getting a tune and adjust the line pressure.

 

[01Konvict]

The tune did help it but its hard to lock a converter that low in the rpm esp when dropping into OD. Anyhow if you get a 2800-3000 stall it will launch better and lockup easier when loaded. It will hardly change daily driving. I will prob swap to a higher stall if I do a cam swap.

 

[sunrisor]

It's searching, I've had that in previous vehicles. Check the fluid level (at operating temp). Maybe needs fluid/filter change. Especially if you tow alot and often.

I have an '03 XL and it doesn't do that.