I have a 94 s10 blazer with the vortec. The truck misses pretty badly under acceleration and shudders at idle. The missing is the worst in 1st and 2nd gear. When I am stopped at a light, the idle is pretty rough and it shudders bad sometimes like it's going to stall out. It has actually stalled out maybe twice in the last 6 months. I'm lucky if the spark plugs last 15k. I think the passenger side always has white ashy deposits on the plugs and the drivers side are fouled out, if not the other way around. I have scoured the threads in search for an answer, but all of the suggestions are things I already fixed.

Here's the list of things that have been replaced in the last year:
O2 sensor
spider injector
cleaned egr
distributor, cap, and rotor
wires
plugs
fuel filter
catalytic converter and a new cat back
all the vacuum lines


I am at a loss for what to do now and would appreciate any suggestions greatly.

 

Have you tested your fuel pressure? The CPI engines are notorious for leaking FPR (fuel pressure regulator) and/or leaking 'nut kit' (internal fuel lines).

 

I haven't checked the fuel pressure recently because I had the FPR/spider assembly replaced not too long ago, but at the time the nut kit wasn't leaking so I didn't replace that. I'm beginning to suspect it though. I'll do a pressure test soon and get back to you. Thanks for the suggestion.

 

I finally got a chance to check the truck out a little further. The fuel pressure is good, and I took a peek inside the plenum, there isn't any washing and no fuel smell. I also noticed that the truck misses all the time, it's just more noticeable under acceleration. Do you have any other ideas of what could be wrong? Thanks for your help Kyle

 

well it could be a few things the first step i would do is to see if you are getting spark to all cylinders all of the time. if thats good check if you are getting spark at the right time (a timing light is best IF your hyrmonic balancer has not spun) depending on how many miles and maitenance of vehicle it could be a worn timing chain. another thing i would check is how much vacuum you are getting and or compression tests. what you could do is narrow it down to which cylinder is misfiring and go from there.

 

When they replaced the fuel injector, did they check/replace the electrical connector that goes to it? The rubber insert tends to shrink over time, making the connector loose and causing arcing and intermittent connection.

 

Blackwoods, thanks for the ideas. I'll check some of that out and get back to you
Leeann, No, we didn't replace the connector, I'll have to look into that as well. Thanks!