I have an 2002 Blazer and I have an issue with it...
It will accelerate fine until it hits 30 mph. The RPM's spikes and it doesn't go over 35 mph. I have a transmission fluid leak (No clue where), but I put more Tranny fluid in it and drive it around a bit, but it still does the same thing. It throws NO CODES Please I would like to know what the issue is....
Thanks.

I also posted a video of what it does on youtube... here is the link

 

I would say you have some sort of transmission problem. When on mine the 3/4 clutch pack went out, it would rev as if I had put it in neutral. Does yours act like that? I have also heard of torque converters failing but I'm not sure of those symptoms. What happens when you top off the transmission fluid? Does it change how it behaves? I.e. running normally until too much fluid leaks out or do the symptoms persist irrespective of the amount of fluid?

I would say a trip to a transmission shop is in order.

 

Symptoms don't change after i topped it off with transmission fluid... Still does the same thing. Engine does rev up as if it was in Neutral. I looked into it some more and heard stuff about my MAF (which i checked), my catalytic converter or muffler, and Spider fuel injector. Then again i replaced the catalytic converters not to long ago... but read some things about my Catalytic Converter clogging up from faulty injectors. I will most likely take it to the shop but it can get expensive and wanting to see if i can fix it myself.

 

Yep, good to check the easy/cheap things first, even if they are not likely to resolve the issue. However, what you describe sounds a lot like what happened when I lost my 3/4 clutch pack. Mine failed because I towed my boat using overdrive, a big no-no. Here is a good video that explains failures that can happen with our transmissions.
If you do have to have the transmission rebuilt, consider doing the parts upgrades that will make it stronger. I had a shift kit installed, a better torque converter installed, and a remote cooler. I wish I had also looked into an upgraded planetary gear too and stronger drive shell. Apparently the 4l65e incorporated many of the upgrades and the parts can be retrofitted to the older transmission.

Good Luck!

 

 

You can do a quick check of the back pressure of your catalytic converter. It's pretty easy and best of all it's free if you have a vacuum/pressure gauge. I found it best to access exhaust system through your EGR ports. My jimmy had similar symptoms, my first thought was my trans. After talking with a mechanic I was told to test exhaust back pressure. Sure enough my converter was clogged. A guy on YouTube "scannerdanner" has some good videos on testing. Best of luck!

 

Well since November he may be still saving for a new or maybe rebuilding the tranny but in his case he was tacking out the RPM's - in your case with a clogged cat you should of built up too much back pressure and engine should have bogged down due too lack of exhaust flow ....