Hey all, my dad has been having problems with his envoy. Its a 2005 4.2 I6 4x4 with a 4L60E transmission. Lately its really been bogging down like when trying to go up hill, sometimes the rpms surge up and down. It had a full tune up not long ago and its not throwing any codes right now. Local shop seems to think the transmission is on its way out, but that just doesn't really seem possible.

If you're easy on the gas it'll go through all the gears no problem, but if you get on it harder it'll bog down. Heres a video to show what i'm talking about, any ideas are greatly appreciated.

 

Keane:

Could be 1 of 2 things...

Either a clogged cat (Since it accelerates/shifts fine with a light pedal)
Or
The trans maybe failing?
Have you tried a fluid filter change lately/ever?
Whats the trans fluid look like? Brown/Burnt not cherry red?
GM used a "Plastic" type filter in those transmissions...
Could be its collapsed/Plugged?

Keep us posted on the resolve.

 

To me symptoms seem to lead to a clogged cat, but our normal shop checked temperatures and there was no indication of anything over heating in the exhaust system. I will have to check the trans fluid and see how its looking.

 

How many miles on it Keane?

I would also have someone push the throttle while sitting in the driveway and check the pressure coming out of the tail pipe...

Or this evening take it for a 25 to 35 minute drive and then look at the cat and see if its glowing red hot? If it is... Then you know it either is or isn't clogged....At least that way... you probably certainly will either eliminate/confirm a clogged or unclogged cat...

 

Little over 82k miles.