Lurching 40 to 50 mph slight hill

Never experienced this in 17K miles so far.

S.

[f5fstop]

How's the idle? Is the engine light on?
Does it only happen when going up a hill?
Sounds like the torque converter clutch to me, which is engaged in 4th and 3rd gear, is going between locked and unlocked.
Could be an engine miss, but three cans of Techron won't help if it is. Techron is good for keeping the engine and injector clean, as well as the fuel sending unit (if using the right Techron).
Can't help much with a long distance diagnosis, suggest a dealer visit.

[Dave LV]

Since it doesn't go away when I drop into 3rd gear, I figure it can't be the AT torque converter locking/unlocking.
No check engine light.
No idle problem.

How does the center dif work? Engine compression problem? But then why only uphill?

Yep, visit to dealer is called for, but I expect they will say "Problem not found".

Can leases be ended due to fundamental flaws such as this if it can't be repaired - i.e. GM says it is normal?

[f5fstop]

Your third gear theory is wrong, 4L transmissions will lock in manual 3rd gear, as well as in overdrive 4th gear.
Possibly an engine compression problem, but if it is the cylinder head issue, it would cause a rough idle, and the PCM would pick up a misfire after certain counts and turn on the idiot light.
As for buy backs, is this your first problem? Call your lease company. But if it natural, it is between your lease company and GM.

I really don't know of any heavy vehicle with an automatic and limited HP that will not do some shifting around on mountain roads. But then again, I don't know if it is a shifting problem or a TCC problem, or something entirely different. Good luck.

[Dave LV]

Interesting. I did not realize that the H3's AT would torque lock in 3rd gear. My other cars only did it in top gear.

But I now believe you are right about the torque converter lockup being the problem. Today I kept the speed going uphill below the 40 mph where it locks up and sure enough there was no lurching.

Lease is with GM and it is the first shop visit - but not where I bought it.

Shifting is no problem with the transmission. I expect it to with the H3's weight/power ratio. Seemed fine until lately.

Still surprised that putting on the brakes doesn't release the lockup. My '01 Camaro did and it made it much more drivable.

[Dave LV]

So the dealer said the lurching/lugging was present in their three loaner H3's also and therefore is considered normal. And since the COMPUTER could find nothing (even though the tech felt the shuddering), it was obviously OK per GM warranty process - what ever happened to good old fashioned seat of the pants repair?

So it is becoming more and more noticeable, and I now dread driving my H3 vs the joy I had for the first 5000 miles.

And unfortunately I still have 31 months to go on my lease.

I guess I will try the GM appeal process, but eventually will most likely have to look into buying my H3 out of the lease and selling it for a huge loss.

I knew I should have bought a GX470. Never have problems with Toyota/Lexus, but I wanted to be patriotic and buy American. Boy what a sucker I was.....

[NEOCON1]

Originally Posted by Dave LV

So the dealer said the lurching/lugging was present in their three loaner H3's also and therefore is considered normal. And since the COMPUTER could find nothing, it was obviously OK - what ever happened to good old fashioned seat of the pants repair? since there is about a dozen computers monitoring everything now days seat of the pants is useless

So it is becoming more and more noticeable, and I now dread driving my H3 vs the joy I had for the first 5000 miles. drive it hard till it dies and push the blue button

And unfortunately I still have 31 months to go on my lease. there is a 48 month waranty so dont sweat it drive it hard till it breaks or you get a warning light they can trace to something

I guess I will try the GM appeal process, but eventually will most likely have to look into buying my H3 out of the lease and selling it for a huge loss. drive it till it dies and push the blue button

I knew I should have bought a GX470. Never have problems with Toyota/Lexus, but I wanted to be patriotic and buy American. Boy what a sucker I was.....

now you sound like a hummer hatin tree licking troll and an anti-american one at that