95 4.3 Blazer running real rough

[rugman]

I have a real pain first let me say great board.

I have a 4.3l that has been running a bit rough for a few weeks now it started with an engine miss on cylinder 4 thought to be bad plugs and wires they were replaced and seem to help but next day engine light back on and a miss is occuring again. CHeck codes found same thing missing on 4 and a possible EGR. I left it like that for a week or so then while driving in rush hour this SUV starts chuggin and stalling running extremly rough even backfiring. I manage to get to the shop to find codes EGR, O2 and miss on cylinders 4,5,6 i changed the EGR opened up the intake changed the spider change the lines and cleaned it out. Still running the exact same. Full presure is a comfortable 51. At this point not sure where to go from here with out breaking my walet.

Im at a loss of guesses and hell of lot of cash to boot and any help would be great

thanks

Rob.

[crank182]

check distributor cap and rotor for arcing or carbon, also check plugs and gap on plugs, if all is good check your timing.

[rugman]

Just a heads up after painstaking hours on this i took a chance and exchange the CPI and it turn out the new one i put was faulty. Let me tell you they heard it at the parts shop.

thanks guys.

[vector006]

Ok, whats the deal with these CPI units. I took my 92 truck to GM, they said it was the CPI unit. So i bought one off ebay, threw it in, and thought it was running ok...but then it started missing again...and i verified that i had spark, and that it was definately a fuel delivery problem. So i sent it back to the guy on ebay, and he replaced it for me...but same problem. What are teh chances that i got two crapped out CPI units. I am out cash on this one, and dont know if i should risk it by buying another one...anyone have any advice?

-jer

[BlazerLT]

Originally Posted by rugman

I have a real pain first let me say great board.

I have a 4.3l that has been running a bit rough for a few weeks now it started with an engine miss on cylinder 4 thought to be bad plugs and wires they were replaced and seem to help but next day engine light back on and a miss is occuring again. CHeck codes found same thing missing on 4 and a possible EGR. I left it like that for a week or so then while driving in rush hour this SUV starts chuggin and stalling running extremly rough even backfiring. I manage to get to the shop to find codes EGR, O2 and miss on cylinders 4,5,6 i changed the EGR opened up the intake changed the spider change the lines and cleaned it out. Still running the exact same. Full presure is a comfortable 51. At this point not sure where to go from here with out breaking my walet.

Im at a loss of guesses and hell of lot of cash to boot and any help would be great

thanks

Rob.

Ummmmm, what about the O2 sensor?

always, ALWAYS do the cheapest first.