Engine running rough.

[bblazer123]

I have a 96 blazer 4.3 It has been running very rough (spudders and sometimes backfires) when I eccellerate and loses power. Yet it idles just fine. Any idea what could be causing this? I have done plugs and wires and cap and rotor and cleaned MAFS and EGR
and the 02 sensors are less than a year old.One thing i think it may be from is my exhaust. I dont have a muffler. Can a lack of back pressure cause this problem? Any suggestions would be great.
Thanks!

[old_master]

Is the SES light on? If so, what codes are stored? A lack of exhaust back pressure will not cause backfiring on acceleration, a lean fuel mixture however, can cause it. Check the fuel pressure and leakdown rate. Post your results.

[bblazer123]

The SES isn't on but i'll check to see if any are still stored but it might be a while till I can get ahold of a pressure gauge.

Thanks!

[blazinman08]

it could also be the timing mine is doing exactly the same thing as of right now backfires loses porwer sputters yet idles fine um i was told it could be the timing havent had time to fix yet so no promises

[bblazer123]

Yeah I also read on another web site that it could be the timing. But I heard that the timing is automatic on 96+ blazers' distributor. So i'm guessing they ment the timing chain or something. Yeah let me know if you find a solution to this problem and i'll do the same. I suspect it could be moister in the distributor cap, seeing how the problem seems to get worse whenever theres a lot of moister in the air. But who knows i'll try replacing the cap and rotor and put some silicone glue around the seal and hope it'll keep moister out... If this doesn't sound like this would cause my problem let me know.

Thanks!!

[dirtyblazer]

i have the same issue on my 99 blazer 4.3 it runs very rough and almost dies when i push on the gas and let off. i changed the plugs, wires, cap, rotor, and i checked the battery and the alternator. but lately the gauges have been acting funny like jumpy and someone told me that the gauges can throw everything off! so i was thinking of replacing the gauges but i dont know what to do. i love this car so much but i don't even know where to start?

and as the guy above said the timing is automatic. so i don"t know if something with the computer or anything else for that matter is the culprit

[HUNTERPAUL]

Sounds like you have a missfire problem I would check the integrity of the ignition spark and also check the distributor for slack in the verticle shaft. The distributor is made of a composite material and had a tendency to wear causing slack in the shaft which will cause an engine miss.