Help 99 Tahoe shudders/ jerks

[99tahoecolorado]

I have a 1999 Tahoe with 180K miles & only 70K on the engine. Runs great, been off-roading in Colorado all summer with no problems.. until now.

It will very lightly shudder/ jerk/ shake. Usually only noticeable on the highway with light throttle. If I punch the gas it goes away, if I manually downshift into 3rd it gets worse.. RPM isn’t affected, no weird noises or sounds. Transmission fluid looks good.

Any ideas? I’ve seen a lot of people talking about the touqre converter or the TCC going bad or getting locked up. Just not sure, a lot of people said they’re shudder goes away when downshifted into 3rd gear.

 

[bigfootchiro]

Could be the TCC. Common on the 4L60E. Do you have a scanner?

 

[dkknaebel]

Is your speedo doing anything weird? Mine wouldn't stay in OD and the speedo would fall out after anything higher than 40. Replaced the VSS, it's running like brand new. Rock Auto sells the TCC solenoid and the harness as well. Not that bad on price.

 

[bigfootchiro]

Hook up a scanner, check for codes, and check your misfire counts. 1) misfires can cause your TCC solenoid to operate improperly, 2) misfires can be misinterpreted as a transmission issue. That is exactly what happened to me. 3 mechanics and a transmission shop said I needed a rebuild. I told them that seemed weird since the fluid is still full and perfectly red. Something to me didn’t seem right, and over $500 later, I found that the cap was loose on the distributor (screw stripped out). Temporarily got the cap fastened down (have a new distributor to put in still), and it IMMEDIATELY stopped the bucking/studdering.

 

[99Vortec]

Hook up a scanner, check for codes, and check your misfire counts. 1) misfires can cause your TCC solenoid to operate improperly, 2) misfires can be misinterpreted as a transmission issue. That is exactly what happened to me. 3 mechanics and a transmission shop said I needed a rebuild. I told them that seemed weird since the fluid is still full and perfectly red. Something to me didn’t seem right, and over $500 later, I found that the cap was loose on the distributor (screw stripped out). Temporarily got the cap fastened down (have a new distributor to put in still), and it IMMEDIATELY stopped the bucking/studdering.

I still do not understand the reasoning behind using a plastic/composite distributor base. Can someone enlighten me here, is it to isolate or insulate?

 

[east302]

It was probably fifty cents cheaper.

When mine cracked, I found a new one made of metal. Arguably, though, the plastic one did last nearly 20 years.

 

[bigfootchiro]

My new one has an all aluminum body. Shouldn’t have an issue anymore

 

[99tahoecolorado]

Sorry for the delay, thanks for all the advice. Finally got some free time, and went a little crazy reading forums, watching YouTube videos & getting to know my Tahoe.

After letting my Tahoe sit for a week longer it would no longer start & battery was dead. Long story short, turns out my biggest problem was distributor cap & rotor. Both completely corroded, fried, & plastic busted lose. I will post picture later today.

Also my spark plugs & wires were pretty fried as well. I replaced all my spark plugs, wires, distributor cap & rotor. It started right up with the first crank... but I couldn’t stop there!

I had a coolant leak that had just recently started, it was from my upper oil coolant line going into my radiator. After reading hours about people trash talk dex-cool, I was almost scared to drain my radiator & see what will come out.

 

[99tahoecolorado]

 

[99tahoecolorado]

Pictures of my Tahoe, feel like people don’t post enough pictures on here.