Hope someone can help, I have a 99 Blazer 4.3. When starting it up I have had #4 cylinder misfire a few times. It doesn't do it all the time (3 or 4 times now), just when it is cold out (Northern Indiana). When I start it up in the morning to warm up, it will misfire, but after warming up it will go away. I have replaced the wires, distributor cap and rotor. Just had a misfire this morning.
Also after the engine has warmed up, sometimes i will get a noise (sounds like ice in a glass) from the same area when pushing on the gas. I now have 154,000 miles on this engine. Appreciate any suggestions !!

 

How do the plugs look?

 

Maybe a bad spray pattern on an injector if the plugs are new buy some lucas injector cleaner. cheap gas will gum your injectors

wires should be ok at idle on the miss

 

Plugs were replaced too. I am going to pull all of them out again and see how they are firing.

I bought one of the big bottles of Lucas Injector Cleaner about a month ago and am 3/4 of the way through it. Think it could have anything to do with the vacuum hoses.

 

My question about the plugs was in regards to their condition. If they were replaced, how did the old plugs look? A condition with a single cylinder can often be identified by inspecting (reading) the plugs.

How are you 3/4 the way through a bottle of injector cleaner over the course of a month? Didn't you just dump it into the tank?

I prefer Chevron Techron Fuel System Treatment Plus due to the added filming agents that clean and preserve the fuel level sending unit, but that lucas stuff does a decent job as well.

 

Qt of lucas treats 100 gallons paid ten dollars at napa