1999 Chevy blazer 4.3 4dr automatic np8…totally lost…Theblazer was running great and shifting great, but the radiator had a leak so Ichanged it. Within a day or so I noticed that after the blazer got to operatingtemperature it didn’t want to shift from 1st to 2ndunless I let off the gas at about 2700 rpms. I have no codes. The TPS was stillunder warranty since I had it replaced last fall when I replaced intakegaskets. So I replaced it again. I also replacedthe entire distributer, new cap, and rotor since I had them out anyway.
When the trans started this issue I changed the fluid andfilter. It wasn’t burnt and there wasn’t hardly any debris in the pan.
The problem is sort of erratic sometimes it shifts fine andat the next stop light it won’t and then the next one it will. Usually it willshift fine as long as I don’t go below 2mph, then there are times when it won’t.
You can usually tell right away if it is going to shift. If therpm’s go up faster than the speed, then it don’t shift.
Trans, engine, orwiring?
BTW Changed all 3 speed sensors in the transfer case, nochange.

 

How many miles you have on your ride?Since alot of newer tranny`s are controlled by a computer.I would take it to a transmission shop, then let them do their magic hopefully they know what the problem is.It sounds like it maybe the shift solenoids are on the brink.

 

its has 165000 but I drove it for 250 miles yesterday stopping several times and it worked fine all day today it only worked for about 15 minutes before I had the problem twice then had to stop and wait for a train about ten minutes engine idling and it worked fine when starting out from there but at the very next stop sign, same issue.


While driving down the road I have slight increases in rpms but not all the time. Tried tapping the brake pedal while driving and it comes out and goes back to the lock up converter, so that appears to be working right.


The trans shops around here are crooks, lol.


fairly sure that it has to be a wire somewhere

 

All depends on if the PCM is commanding the trans to shift - and how the trans is responding to that command (or lack of command). Honestly, a proper scanner and experienced transmission technician is what you need. Otherwise it's all a guess.

I can say that Car Gauge Pro for Android will monitor commanded gears and tap cell data and other transmission stuff, but it does take some interpretation to know what it all means. A proper scanner with bidirectional communication can actually command the trans to shift into any gear at any time, thus eliminate a lot of the possibilities. I'm sure there are even a lot more things that can be done with a Tech2.