Well Just yesterday my egine started to stall and idle irratically and then the "Check engine soon" light pop up. I am thinking it is a head gasket since it only happens when it gets to opperating temp. I just change plugs a month ago to A-4 could that be it. I had a big debat on that a while ago and basically those plugs are bad for the blazer but I am not sure that it can cause such a big problem. Do pcv valve do this stuff. I got to get a code reader which one is a good one and where do they sell them the cheapest. I know Autozone has one but looks cheasy. Please help thanks. Swart good luck with that leak.

 

By the way it runs fine just at idle and warm.

 

How does the truck run when you drive it down the road? If you have a bad head gasket, you'd be loosing coolant... An easy check for a faulty head gasket is contamination in the oil and coolant (ie. oil and/or combustion by-products in the coolant and coolant in the oil). Another check would be to pull the radiator cap and warm up the engine. If you have a bad headgasket, you should see bubbles in the radiator.

WARNING, if you remove the cap when hot, hot coolant will come out and may burn. If you remove it prior to warming up the engine, the expanding coolant may spill out as the engine warms up.

Now, on to other things that could be causing the symptoms you describe. Even though I can't remember the year of your truck, it probably has an idle air control (IAC) valve. If the IAC passage in the throttle body has gotten carbon'd up, it would cause idle problems. I would pull of the throttle body and thoroughly clean it. Make sure that you don't drop anything down into the intake. The upper intake plenum cover isn't all that fun to remove!...

You've got conflicting statements on your problem. One post says that you have problems with idle quality and stalling once warmed up, and the second one states that it runs fine when warm... Which is it? Please elaborate as to the symptoms you are concerned with.

My statements on the +4 plugs were not that they won't work like any other plug, but that they do work like any other plug so why spend extra money for a gimic. After a few hundred miles, the other 3 electrodes do nothing. Plus, they won't have the life of a double platinum plug because they aren't using platinum contacts on both the center electrode and all of the ground straps. The 4.3L (96+) was designed to use platinum plugs so it will get the best plug life out of them. Non-platinum plugs will not last as long. Since the AC Delco Double Platinums cost practically the same as the Bosch Platinum +4's, I'd go with the Delco's (or any other Double Platinum plug - NGK, Autolite, Champion, Bosch conventional plug, etc).

 

It only idles irratically and stalls at idles but high rpm it does not do it. It ony happens when warm.

 

Definitely sounds like either a dirty TB and/or a sticky IAC. Like I suggested before, I'd pull the TB and clean EVERYTHING on it. Remove all of the electronics (TPS and IAC). Clean the pintle on the IAC as well as the sealing surface that it seals against. Try that. Atmost, it'll take time and about $5 for a can of sensor safe TB cleaner.

 

Could it be the fuel pump or filter but would that make the engine light pop up. What is the easiest way to check the pressure of fuel?

 

Fuel problems should be more apparent at higher rpms, not at idle. Do you have a 'Check Engine Light' on?

 

yes

 

This is a 95 Blazer by the way fuel injected 4wd.

 

I'd find out what the stored code is before attempting too much trouble shooting. Head on down to your local Autozone or Advanced and have them scan the PCM.