pcm or tranny questions
 

Hello Everyone,
It's been awhile since I've been here. I should have continued a previous post with all the things I've done but searched for 15 minutes or so and said the hell with it...lol
Anyway, basically I have the engine in good shape. I now believe most of my earlier issues were coming from the present problems. As I'm driving, I will feel hesitation while driving a constant speed. For a very long time, I assumed it was an engine issue. After kinda replacing most everything above the pistons and crank, I have decided that I have either a short in my "ecm" or "pcm" or, I have serious issues with my tranny. This is what it's doing...
Driving at a steady speed anywhere between 35 and 60, I have what seems to be a misfire. I'm almost certain it's not a misfire. I believe a ground short in the pcm that happens erratically or something about the tranny. Anyway when driving the issue happens and it seems like a miss but the tach rpm raises about 200 rpms every time you feel the so called miss. That's pretty much the problem. Any input would be appreciated.
Thank you

First, what year and mileage and are there any mod's to your Blazer. Second, any CES/ MIL codes and what are they? Third, when does this 'misfire' happen: When the engine is cold or fully warm? When driving on a level hwy or when driving up a hill?

Hello,
96' 4.3 v-6 with 120,000 miles. no codes. It's very random, some days hardly at all but some days are horrible.

Last April my Blazer started doing what felt like an occasional sharp random misfire between 50-55mph at steady speed on level road. Never higher or lower. Almost always at steady 50 mph in 4th gear. Maybe once every few seconds. Really irritating. Basically no codes but did notice that it set a pending random misfire once. Sometimes problem was better than other times. Transmission ended up shelling 3-4 clutches on a 250 mile round trip to O'hare Airport after a few weeks of doing it. Not saying this is what has to be wrong with yours - just keep it in mind, especially after all the misfire diagnosis you have already been through. I know I learned something that day.

Maybe pull the trans pan and take a look for material? When mine shelled there was so much material in the pan getting sucked up against the pickup that it would howl and start slipping. Stop and then would fall off and would move again for a little bit. Trans was rebuilt (again) and the problem disappeared, so I assume the "misfire" had something to do with the trans.

Thanks Les,
You always know where to get the good info...lol.
I'm kinda leaning toward the tranny, just don't want to spend that kind of cash right now

Well, I stated earlier that I was leaning toward the tranny for a fix but...The other afternoon I was preparing to pull out of the parking lot from work and started feeling the so-called misfire issue or transmission issue,(who knows) but I was sitting still.
I believe for everything I've already done to it, another 200 bucks for a computer might not be a bad choice.
Exactly how is this exchange done? I think you send it in with the vin number and the mileage. I also think I read somewhere about pulling a knock sensor. After everything has been exchanged and installed, will I still need to see a dealer for some kind of reset?
Btw, I've noticed when this issue is happening, my rpm jumps about 200 rpms for just a second. Sometimes my antilock brake light and my emergency brake light also come on for no apparent reason. Usually I'm running down the road about 45 mph.
Thanks

I tried a used PCM once from an online service. They programmed pcm per my vin and shipped to me with instructions how to reset the theft deterrent. All went exactly as they said. However PCM did not fix my problem and they refunded minus shipping for what I considered to be a reasonable fee. At least I knew it wasn't pcm. This was back when I had an occasional miss and SES light eventually found to be due to injector wires melted on front of passenger exhaust manifold (my fault after replacing engine)

Hey Les, how's it going?
Yeah, I saw a rebuilt for 129.00. I've already spent much more than that plus more labor than that would take to change out. I believe they had a 20% re-stock fee plus shipping but it would eliminate that at least.
Later

sounds like the same place I used. Nice people. Good luck.

Do you happen to remember the re-learn procedure?