I have a 2000 Chever Blazer 2DR, 5 Speed. I have changed out my exhaust and my air intake. It currently has a 40 series flowmaster with no catalytic converter and a K&N Cold air intake. My Blazer has been running great until it started missing. It would always get worse when you tached over 2 grand. Check engine light came on so I got it scanned. It showed up random multiple misfire. So far, I have replaced plugs, wires, distributor, cap, rotor button, and the spider fuel injection. One of my partners told me that it was probably my computer causing the problem since I dont have the OBD 2 catalytic converter on it and plus my oxygen sensors were probably shot. Has anyone had this problem before because so far, I've spent over a grand and still my ride is spuddering.

 

Try checking the compression, and checking for vacuum leaks. Check the compression first though.

 

I dont think it going to be anything to do with the compression because when it starts to stall out,you can punch the accelerator and it will take off with out hesitation. The power is still there. It just start stalling after your speed starts to level off. I will check all of my vaccum lines. Any suggestions of which one it might be.

 

The computer is getting a bad signal, because you no longer have your catalytic converter in.

You have TWO oxygen sensors, one BEFORE the cat and one AFTER they're tuned to read specific readings.

You either need to get you computer reprogrammed, or reinstall a cat. A highflow cat, is probably your best bet, I don't think they trip the 2nd oxygen sensor...

 

The down stream O2 sensors have nothing to do with fuel delivery. This sensor is for catalyst monitoring only. At most, the lack of a CAT would cause an SES light, but an O2 spoof could eliminate that.

If your O2s were bad enough to cause a miss-fire, you'd be getting codes for them as well... Or atleast you should be.

I'm wondering if this isn't an EGR problem...

 

I messed with this same problem for a while, and while i did not spend quite as much as you have in the end all I needed was an O2 sensor. (bank 1 sensor 1) I was getting a number of different codes, but the O2 sensor never threw. After fixing all the other random sensors, a friend gave me a used O2 sensor that was still good. Put it in, cleared the codes and all better.

 

My catalytic converter suppose to be in this week and I've already got my 02 sensors ready to put in so hopefully this will be the end of this problem.

 

Got my converter put on my Blazer this week and it ran alot better. My computer was holding a code so I had it scanned one more time. It was still showing that random multiple misfire. So I check all the vacuum lines and replaced them anyway. Also check the plugs and wires. I removed the rotor cap and found that carbon had built up on my rotor button so I cleaned it off and now it runs great. Thanks for all your help guys.

 

Sometimes you have to clear the codes from the computer before they go away...

 

just unplugg the neg batt terminal for like 30 seconds and it will clear them, but make sure that if you have a stock radio you have the code to unlock it or you will be rocking out to the sound of wind.