Blinking SES - Rough
 

Hey Guys, any help with this?

Steady and then Blinking SES light all the time...blinking then steady...and so on.

Running VERY rough most of the time, but not all. Sometimes it idols and runs fine like there is nothing wrong, then it starts up again with a steady light and sometime blinking.

I just had the oil pump replaced by a local tech. The SES light was on at the time and he changed the O2. He noticed the blinking light and rough idol/running and changed the spark plugs but that didn't fix it. The code says its misfiring cylinder 3 and the MAF. He swapped the MAF with one he had but that didn't work either.

What should I do? What could be the problem? Should I take it to a dealer, Chevy trained tech?

Thanks for any help!

Without knowing what year your truck is or what the actual DTC is, I would guess that you haven't changed the wires, distributor cap and rotor in a while. Give that a try and see what happens.

2003 Blazer LS 4x4

A blinking SES light means that you have a potentially damaging misfire condition. If you are consistently getting a #3 misfire code, I would test the compression on that cylinder and see how healthy it is.

Sounds like big bucks to test compression

You remove the spark plug and thread in the compression tester... The tester itself is not all that expensive and can be loaned from some autoparts stores.

Which one is cyl 3 when looking under the hood from the front?

4.3 v6 motor

Thx

Middle cylinder on the driver's side.

Bringing this back from the dead but i have the same problem with my 96 4.3 it runs great except the idol and the light blinks sometimes and solid other times. I didnt know if there ever was a answer to the problem ? I have done plugs, wires,cap thinking it was a problem but nope. Could it be the cat ? it has 170,000 miles on it but not sure if this is the original ?

This sounds like so many who have their fuel injector spider assembly on the way out. I would check through some of the many spider injector threads that we have on here for more info.