99 4L60E Tranny Problems When Cold

[mistaake]

I'm a bit annoyed - kinda bought a low mileage truck (it's got 126K on it now, had it for a few months so far) to avoid transmission problems but oh well lol.

A few days ago, I started having this issue. First cold start in the morning the transmission shifts really bad. I'm not really sure how to describe the problem but maybe its slipping a little and then shifting really indecisively?

I was suggested that it might be the throttle position sensor so I checked that with my scantool and it seems fine. it's not cutting out and the signal is smooth.

Yesterday I had the transmission fluid and filter changed. This morning it still acted the same way. I put in about half a bottle of K&W TransX... we'll see what happens tomorrow morning. If it still does it I'll add in the rest of the bottle. But besides that, what can I do/check?

No codes of any sort.

 

[beardeddummy]

The transx will eventually kill all any of that does is swell the seals and make em turn to mush

 

[beardeddummy]

My advice have someone build it with at a minimum vette servo 700r4 steels and 7 hi energy 3-4 clutches

 

[Jrgunn5150]

Is your coolant temp sensor, the one that feed's the ECM working properly?

 

[michael hurd]

I'm a bit annoyed - kinda bought a low mileage truck (it's got 126K on it now, had it for a few months so far) to avoid transmission problems but oh well lol.

A few days ago, I started having this issue. First cold start in the morning the transmission shifts really bad. I'm not really sure how to describe the problem but maybe its slipping a little and then shifting really indecisively?

I was suggested that it might be the throttle position sensor so I checked that with my scantool and it seems fine. it's not cutting out and the signal is smooth.

Yesterday I had the transmission fluid and filter changed. This morning it still acted the same way. I put in about half a bottle of K&W TransX... we'll see what happens tomorrow morning. If it still does it I'll add in the rest of the bottle. But besides that, what can I do/check?

No codes of any sort.

Perhaps installing a temporary line pressure gauge would give you some insight on what is happening. You may have low pump pressure in the transmission. Pressure port is above the shifter shaft area on the driver's side.

A transmission shop should be able to pull the plug and install a gauge, take it for a spin.

http://www.ebay.com/itm/OTC-Transmi...:g:waQAAOSwjVVVpaKv&item=222288511465&vxp=mtr

 

[mistaake]

Alright so the transx "fixed" it. If the problem comes back I'll send it over to the shop for a proper diagnosis and repair.

 

[Jrgunn5150]

Must be a worn valvebody then.

 

[mistaake]

Must be a worn valvebody then.

At 126k? Garbage.

 

[Jrgunn5150]

At 126k? Garbage.

Steel valves in aluminum bores are, yep.

 

[mistaake]

Steel valves in aluminum bores are, yep.

Nobody can convince me that the 4L60E isn't one of the biggest pieces of garbage GM has put out. I've had three issues with them all at low miles:

-96 Yukon @ 115K - loss of 3rd and 4th
-07 Colorado @ 70K - loss of reverse

and now the 99 Suburban @ 126K - though I'm hoping that it'll survive for another few years with the TransX crap in there. I'll tell you right now I'm never servicing the tranny again and I'm annoyed that I wasted $150 on a fluid and filter change.

I do intend to keep this Suburban for the long haul instead of getting rid of it when there is a major problem like I have in the past (I should have just put a junkyard tranny in the Yukon and kept it). My Suburban still drives fine though my dream of getting to 200K on the original drivetrain is gone for sure. I'll be satsified at 150K.

PS: While it is fine now my 02 Envoy (I'm the 3rd owner), the first owner had to rebuild the transmission at 100K. It's doing fine at almost 200K now but if the average 4L60E lasts 100K that is clearly just low quality and lack of care for the customer.

What sucks is every damn GM SUV and truck within my price range has a 4LShittyE