Hey guys, an issue with the shifting just started on my zr2. I always do a drastic search before I post a new thread. Can't figure this one out.

Vehicle info-

1998 blazer zr2 auto tranny. 140k miles, very well taken care of. Tranny fluid and filter change (NOT FLUSH) done about a year ago.

This last weekend I drove the blazer on a small road trip about 400 total miles, all of which were on the highway at 85 mph with cruise set. Car ran and drove fine that entire trip.

The next day on my normal 10 mile trip to work the car started shifting weird. As I went to pass someone it didn't want to down shift. It revved up like it was going to but wouldn't shift until I let off the gas. It's now doing that with every gear. There is no slipping and when it does shift they aren't harsh or anything. Seems to be the same with all of the gears. Manual shifting through 1-3 work fine as well. Fluid level is good and doesn't look or smell burnt. There is no CE light or trouble codes at all.

After doing some research yesterday I decided to change the TPS and swap in a extra PCM I have that I know is good. No change.

There doesn't seem to be a loss of power or anything, just doesn't want to shift properly. If driven normally in 'D' it will just about redline, then shift. Very late/delayed unless I let off the gas.

Any input/help with this would be greatly appreciated.

 

It could be shift solenoids just starting to go on you. They're not that hard to change out if you don't mind getting messy.

 

Is there any way to narrow it down to this without dropping the pan? I did the fluid change myself so I know what you mean about getting messy lol. Should have installed a drain plug while I had it off last fall!

 

Once the solenoids get worse they may set a code, but I don't remember off hand what the code is. If you don't have any codes set, then I'm not sure how to test it. My only experience with it was my brother and I fixed a ZR2 that would not shift into 1 or 2 when in Drive. It would manually shift there if you selected 1 or 2 on the shifter. In Drive it would start in 3rd gear, and would automatically shift into 4th too at speed. It had set a codes P0756 and P0758. We replaced both the 1-2 and the 3-4 shift solenoids and now it shifts perfectly. If you do find DTC codes, check here for help diagnosing and resolving the codes.

If you did the fluid and filter change then you know exactly what's involved. Once you drop the pan the solenoids are right there.

 

Yeah I think a drop of the pan is my next move. I do remember I left the old seal for the filter on instead of trying to pry it out. I was a bit worried the filter might come loose and drop to the pan at some point. Wonder if this could have possibly happened?

Thanks for your help

 

Drove it to work again today. I can literally make it shift when I'd like by letting off the gas slightly. Going from a stop, if I keep my foot at a steady half-3/4 throttle it wont shift on its own until close to 3500-4000 rpms or until I let off.

Think I'm going to drop the pan this weekend. Any other suggestions on what this could possibly be?? This is my daily driver so any help is much appreciated. I like to do any of the work I'm capable of on my own, but I have very little experience with transmissions.

I've heard bad/shady things about the transmission shops around town so I'm hesitant to take it to any of them..

 

One thing I forgot to mention is the previous owner said there was a b&m shift kit installed as well. Could this possibly have anything to do with it?

 

After driving it again today I don't think it's shifting into second while in drive. Goes from 1st to 3rd...l

 

Quick update on this issue:

Ended up taking it to a transmission shop for diagnosis. Wasn't getting anywhere trying to figure it out myself having little experience with transmissions.

They told me it seems to have a busted 2-4 band. Wanted $800 to go in and fix the main problem but obviously suggested a rebuild for $1800. I hoped it would be a easier/cheaper fix than this, being money is VERY tight for me at the moment.

After searching around and talking with people around town, I found a guy that does full tranny rebuilds for $600 with a 2 year warranty. This price seems very reasonable campared to all other prices I was given. The best part is this guy specializes in 4L60E and 700R4 transmissions.

Guess my next venture will be pulling my first transmission ever
Hope I'm not getting in over my head. With first and third still working, is it safe to drive for a week or two; or is the risk to high to be worth it?

 

Did you ever try changing the shift solenoids first? I still think that could be your problem, but I'm no transmission specialist. I just think that changing a couple of $20 solenoids is a whole lot cheaper and easier than pulling the whole tranny for rebuild.

I think you'd be ok driving it as long as you're not hard on it. Another option is you could probably find a used tranny on Craigslist for not too much. It's your call though. Best of luck!