1996 Blazer with the 4.3 engine vin W. I have a misfire code of 303 which is misfire on cylinder 3. I have replaced cap, rotor, plugs and wires. Also replaced injector no. 3. Problem still exists. What is even weirder is the truck starts just fine and accelerates fine except when the throttle is 3/4 or greater while driving, than i lose lots of power. The engine struggles to accelerate. Engine also misses when idling. The blazer shakes when idling so it is missing pretty badly.

This problem has me baffled.

Any thoughts, comments appreciated.

 

Have you tried cleaning the MAF sensor?

 

Dardamar, The service code P0301 is for cylinder #1, not #3!! First since you have already tuned it up, trya compression test. Ifthat is okay, take the injector you took from cyl 3 and put in place of cyl #1 injector. Also check for vacuum leaks. Good luck!! P.S. misfire codes corespond with the cylinder #. P0300multiple cyl miss, P0301 #1, P0302 #2, P0303 #3, Etc. Hope this helps! Korey.

 

no i have not tried to clean the maf sensor, I will give this a shot. Sorry Korey for the confusion, but I did a typo. I meant error code po303, not 301, and I did edit my original post. Good catch.

Thanks for the help thus far.

 

I would still check the compression!! And check for vac leak. FYI If you are having issues with multiplemissfires only on one bank, that is when I start to look at the O2 sensors. Good Luck, Korey.