Let me start with my information.

2001 blazer 4door 4x4
185000 miles.
new plugs 4000 miles.
new wires1000 miles.
new rotor cap 4500 miles.
new rotor button 4500 miles.
oil change 1000 miles.
air filer 1000 miles.
cleaned egr, intake, and mas 4000 miles.
fuel filter 30000 miles.

There might be some more and if i think of it i will list them. As you can tell this problem has been going on for quite sometime now. Well i though i had it lick when i changed the plug wires sometime last week. The monday after thanksgiving weekend to be exact. I has been running like a dream since then till today which was a great stress reliever for me. I drive close to 200 miles a day to workwhich takes me through some pretty rural areas where you dont want to break down. On the way to work today it was running great till about 5 miles from work i stopped at a red light and felt it idling rough. When i took off from the light i was runing rough then the ses light started blinking. I have been use to for a while but this time it was different. This time it seems to be idleing rougher this time and when i hit 30 mph the light starts blinking. Before the light would only come on under hard acceloraton then quit blinking once i get out of the petal. All day today it was like clock work when i hit 30 mph the ses would blink. I didnt try any harder acceloraton today until i know more about this. I did notice that the exhaust tone sounded differnt. The only way i could decribe it would be as spaced out pops. If you could give a better worddescription on how it may sound i could give a yes or no. Any help would be great. I need i well running truck toget back and forth to work. Oh btw what is the sensor for on the driver side engine block kinda underneath the the spark plug closest to the firewall. I hope thats a enough for someone to give me some advice. ANy question or tricks u may need me to try please ask.

 

You need to get the code for the SES light read and tell us what it is so we can try to help with the fix.

MOVING TO 2ND GEN TECH

 

A blinking CEL is a clear indication that there is a potentially damaging misfire. What has the weather been like?

When you cleaned the EGR valve and MAF sensor, how dirty were they?

 

Egr valve and mas were not to dirty to my eyes. The egr vale was replace when i bought the truck 2 years ago. As far as how the weather has been is hard to answer. I live in florida. The best i can remember its been pretty fair. REally no rain just some cold snaps. Heavy rain today though. I will try and get my puter scaned today but they say there not allowed to scan in the rain so well see. Yesterday when i started running rough again it was a warmer day and just windy thats all.

 

I would remove the ICM and have it tested. There is a good chance that the ICM is not passing the spark through appropriately, causing the rough idle and the misfire. While you have that off, it is not too much more work to remove the coil and have it tested as well. Testing both of these repeatedly will allow them to heat up and may bring out failures when hot (operating temperature) that do not show up when cold(cooled off).

 

OK ifs its not to much trouble to you explain how to do this. Where are the location of these items and where or how do i test them. thanks

 

Advanced Auto, Autozone, etc should have the proper machines to test these items. The coil and the ICM are mounted on the passenger side of the throttle body near the distributor. All that it takes is a small screwdriver and a 10mm deep socket, an extension, and a ratchet.

 

Thanks for all the help but it turns out that and unpluged spark plug would cause there same results. Well i guess thats what it was. I used a wire tested and seemed like i had a weak light on the plug behind the steering colum so i wiggled it around. I didnt think it fixed anything but i started it up to test the other side and when walking around the truck i notice the exhaust note was back to normal so i drove it around the block and it was running fine.
Thanks again for all the help

 

So a wire had worked off of the plug so that it was not making contact? Sometimes it is the simplest things. I have seen where a plug wire will push off of the post on the distributor cap due to a build up of air pressure inside of the boot. I always push on the boot with a small screw driver to allow the air to escape for that reason. The use of dielectric grease can make this worse, but I always use dielectric grease!

 

lol i hate that
you get to thinkin its a serious problem and you find out
its a very obvious mistake. those types of things drive me crazy lol