Hey everyone!

I drove my Blazer about 100 miles 2 days ago and it was wonderful, but yesterday it started jerking!!!

Here is what happens... Ones the engine gets hot (I drive away from my home), it starts to lose RPMs (and obviously the speed) when I'm just cruising. It happens between 25-55 miles per hour (I don't know if it will do the same thing if I go faster, I didn't try). If I accelerate quickly it works fine. My question is, is it the engine or the tranny that is malfunctioning? Could it be the gas that is bad? Could it be the computer that went bad? Or maybe the MAF sensor?

Thanks alot in advance

 

Check Fuel pressure to see if Fuel Injectors are getting enough fuel? a thought!

 

You may have some bad gas or water in the gas. As a cheap check, next time you fill up (or right now), just dump a can of ISO Heat into the tank. I have to do this on my Bravada every now and again cause for some reason it likes to get condensation in the tank.

 

This sounds like dirty injectors, but it really could be anything. This sounds more like an engine problem so I would probably start there. The reason it sounds like an injector problem is because it jerks which means its not getting a nice even spray of fuel. I dunno, try a seafoam treatment. That may fix it, if not at all...at least it cleaned your engine.

 

Has the fuel filter been changed recently? I have had the same symtoms with mine an the filter was clogged, it would run but rough as heck.

 

Thanks everyone for your time and help! Me and my dad were thinking the computer has to be the problem, so we cleared the codes on it and now my Blazer is healthy as a horse

Here is how we did it (I don't know if anyone heard of this before but I thought I will tell it to the public (you all)):

1) Disconnect the Negative from the battery.
2) Press and hold the Brake pedal firmly for 20 seconds.
3) Connect the Negative to the battery.
4) Start the engine, rev it up to 2,000 RPMs, and hold for 10 seconds.


I know it sounds weird, but trust me on this, I know it works. It fixed the problem that I was talking about above. I can't believe it my self but as long as the car runs smooth...

See ya'll around!

 

Did you read the code before you cleared it?
If it starts jerking again, have the code read before you clear it.
There are all kinds of possible problems that could be the cause of jerking from fuel to transmission or one of the many electrical or emmission controls, clearing the code may only be a temporary cure.

 

Clearing the codes is a temporary fix. Not only did you clear the codes, but you removed all of the learned values. It takes time for the PCM to relearn the most efficient values for operation. This period of time is called the drive cycle and I bet your problem will come back once the PCM gets through all of its checks.

Now this does narrow it down to a certain extent. It should remove any question about the quality of the fuel, the prescense of water, or the possibility of a clogged fuel filter.

 

It sure did start jerking again... so what is causing the problem? I have a brand new fuel filter. Also my 4X4 switch sometimes blinks back and forth between 2hi and 4hi, it doesn't engage into 4hi until I actually press the 4hi button though. It blinks wile I travel on the Interstate around 70 miles per hour. But when I am stopped, 4hi and 4low works great.

Do these two problems have anything to do with each other?

Many thanks to everyone once again for your time and all the help!

 

Fuel pump could be going. Change the fuel pressure regulator too. Good luck.