Low power/no acceleration after warmed up
 

Hey guys,

I've had my blazer 99 for over 5 years now, over the past year it has been getting really low on power after warmed up and hard acceleration, the last couple of months it has got even worse.

Basically, if I push the accelerator down by an 'average' amount, there isn't any noticeable problem, it accelerates normally, however, if I push it to the floor (after warm) it is incredibly unresponsive, it's like it isn't sure what it should do.

If I'm doing about 50mph and the floor it, it hesitates, then changes down a gear, no acceleration, so it changes down another gear, and still no acceleration. The speed stays the same. It only does this after it's warm. When engine is cold it accelerates normally.

I should mention that a couple of times while warm, and in the summer, I would pull up to traffic lights and the engine would just cut out, it would restart immediately after turning the key and drive as if nothing happened. It hasn't done this for months, or ever in the winter.

I thought the issues could be the transmission or torque converter, but I had it serviced and trans oil changed and there weren't any issues.

So, over the last couple of weeks I have changed the air filter (which was in terrible condition, I wouldn't be surprised if any chunks of it found it's way past the wire mesh and into the intake :s), I have cleaned the MAF sensor, and this morning did the EGR.

I felt like it could be the EGR, but cleaning it hasn't seemed to make any difference.

You guys thoughts would be appreciated :)

Thanks,

Adam

I had the EXACT same problem with my 01, and it slowly got worse, to the point where it wouldn't go above 20MPH when warm. The catalytic converter was the culprit in my case. There are 2 different styles of exhaust on the 4.3 blazers, and I can't seem to find exactly where the cutoff is between the two, but most blazers have a bolt in cat that is replaceable on its own, bolted to a 1-piece Y-Pipe, whereas others have the cat as part of the 2 piece Y-pipe, with a smaller cat on the passengers side of the Y. The latter is not at all fun to deal with, and vastly more expensive.

I've been experiencing similar symptoms in my 2000 Blazer 4WD.

Once the truck has been driven a little while, I experience sluggish acceleration for a moment until the truck decides to shift into a higher gear. It sounds like a huge fan blowing under the hood. I notice the Temp gauge likes to toggle a little past the middle when this happens.

I replaced so many sensors already. Cant figure it out. My only thoughts is bad O2 sensors or clogged Cat Converter / Muffler.

Any advice on this symptom will be much appreciate...

Not the answer you need, but an unresponsive EGR would be bad ping at part throttle. EGR at all time would die at idle.

had the same issue, replace a ton of sensors and exhaust and a few other things and somewhere in there it got better, honestly cant remember what i replaced that made it better. but id start with exhaust and work from there, went from stock to duals on my 2001

Low power
 

EXACT same problem with my 01 Blazer. Took it to muffler shop this AM. The first (smaller) cat insides were shattered and blocked the second (larger) cat. I eliminated the smaller and had a new larger one installed. Works like a charm now. Hope this helps!!!! It did with mine.

Big dean/ Krafty,
Thanks for the response. Im going to look into ordering a new exhaust system this week. I'll leave the headers alone.

I'll post back the end results with the new repair.
*crosses fingers*

Take a look at Summit Racing. Just replaced the cat/pre-cat/y-pipe with one from them minus the pre-cat. $170 shipped to my door in very short order. Direct bolt in for a 2000 2dr 4wd. You will only need to get the gaskets.

AJ - thanks for the tip!

I just ordered a magnaflo cat direct fit ($607) and the gaskets you mentioned all from summit racing. Also used the online assistant to get the right part number for the gaskets. Pretty cool feature that summit racing offers.

Figured I'd go ahead and grab the O2 sensors from amazon.com. (ACDelco AFS105) as well. $25.00 ea x 3
Cant beat that!

As soon as it arrives, I'll install and update.

Update:

Installed new muffler, direct fit cat converter, & 3 new Oxygen sensors.

Drove around for a few miles and the truck was running fine. As i drove into around the 8th mile, the sluggish acceleration surfaced. (Along with the loud fan noise when accelerating)

Im completely lost and frustrated now...