Vehicle: '01 S-10 Blazer 4 door 4.3L 2WD Automatic.Hi all, I've been having this mis fire issue for a while now. I've noticed that replacing the distributor cap fixed the problem the other time I was having a mis fire. It's been about a year now and I'm getting a mis fire again. It's to the point that sometimes I have to hit the throttle a bit to turn on the car since it has a very low idle (at times). I haven't diagnosed it yet, but I'll have to use the scanner to see what codes I'm getting. Just thought I'd ask this question since it's already the third time I'm having this issue and the distributor cap seemed to fix the problem the other time. The Blazer was smogged 2 months ago and passed great, so timing shouldn't be the problem;atleast that is what i'm thinking. Looking forward for your feedback and wondering if any of you guys have had a similar problem or happen to know what the problem may be.

 

How many miles are on the cap and rotor? They don't normally go bad very often, but if cheap parts were used, they can create issues and require replacement often. I would check for vacuum leaks first as its usually fairly easy. If you're CEL is on, pull the codes and post up what you're getting.

 

Not sure how many miles are on it. I want to say, 7,000 miles. I don't remember if I bought the cap and rotor from Napa or Orileys auto parts. Will definitly check the vacuum hoses and check for the codes today if I get a chance and I'll report back with my findings. Thanks for the input.

 

Got around checking it. I'm getting CEL P0140 and I also noticed that when the vehicle is idleing at 500 RPM's the temp gauge is at normal operating (1/4) and when it's idling at 1,100 RPM's the temp gauge is at 100 Deg. Also noticed that when the temp gauge is at 100 Deg. the Blazer feels like it doesn't have much power, but when it's at normal operating temp, it's good. Vacuum hoses were in tact and in good condition aswell.Any thoughts? Thanks

 

I'm sorry... Those numbers make absolutely no sense.
EDIT: I See from looking up images you mean the first demarc after 100. NOT NORMAL operating temp. Normal is just left of 210 deg. About 195.
Either you thermostat is bad or your ECT sensor is.
500 rpm is not normal idle speed and neither is 1,100 rpm. Normal warmed idle is 650 rpm. If your car idles at 1,100 for more than a second or two right after cold starting, it's got a serious problem. Likely an air leak. If it does so hot, it's worse.

P0149 is the post-cat sensor and nothing to do with affecting performance. Fix the driveability problems and it may be ok.