I just got an 1998 Blazer 4.3 liter V6. I love the 4 wheel drive, and power. The power is fine on the unit when driving, and there are no misses. When the Blazer is idling it idles rough. It idles the roughest when it is warmed up. I am not having an problems starting the SUV nor does the Blazer stall. The mass air flow sensor has been replaced a couple weeks ago. I also tried using SeaFoam in the tank, since I thought the tank might have water in it. The seafoam did not help any. What should I do? I have read several forums saying it could be an EGR valve clogged. If this was clogged, wouldn't the check engine light come, since this valve is part of the EVAP system? Also, a few weeks ago my Check engine light came on and took to the shop, and they found a EVAP hose toward the gas tank that was leaking. They replace that part of the hose, and also put an new EVAP Solenoid on. I don't won't to waste my money toward buying things that not the problem. Any help or tips to help solve the problem would make me happy. If this has already been posted in the past, please post the link. If it is I am sorry for reposting this. I looked to see if has already been posted and I am not finding one. Thanks for reading the post, and thanks a lot if you can reply and help me out.
Thanks

 

Well, the truck is 10 years old, after all. If you have no record of the plugs, wires, cap, and rotor being replaced, then I would do so. I would also change the fuel filter and then see what the performance is like.
And [sm=welcomesign.gif]to the Forum.

 

The EGR can be hung open by a very small amount (enough to affect idle) and not trigger a code.

Also, the EGR valve is not part of the EVAP (Evaporative Emissions) system. The EVAP system's function is to capture the fuel vapors from the tank.

 

Okay, thanks for the info. I am glad to know that the EGR is not part of the EVAP. I am starting to learn stuff!!! Okay so what does the EGR valve does? I will buy some cleaner, and an new gasket to clean it. It there any special things I need to do taking it off and putting it back on? I bought the car of an dealership, and I think it got services from there, so I will call them and see if they know if the spark plugs, wires, and cap have been replaced. With this model there is a spark wire going from cap to another device. Is there anything I need to replace on that other device, like maybe an button or cap on it? I found some wires from AC DELCO from advance auto parts, but they want 150.00 bucks. Is this worth it, or are there other recommendation for spark wires? Also what brand of fuel filter do you recommend, and what brand for the cap and spark plugs? Will replacing the rotor help? Is it hard to change the rotor. I can change my own breakes and change my fluids, and general maintence, but isn't the rotor is a hard piece to change. Do you have to make piston onetop dead center (tdc)or something like that. Thanks for the tips, keep them coming. Thanks for the welcome.

 

The EGR vavle (exhaust gas recirculation) is an emissions device which allows burnt exhaust gasses back into the intake. The primary result is lower NOx, but also, due to the lower combustion temperatures, it serves to decrease the tendancy for predetonation allowing for greater spark advance. A non-functioning EGR system will deminish the performance of the vehicle if other procautions are not taken (PCM modification). A leaking EGR valve will also result in drivability concerns (poor idle, etc).

 

Stick with AC Delco plugs, others tend to cause problems in these engines. The rotor is very easy to change, especially as you'll be changing the cap. Its located under the cap and all you have to do is remove two phillips head screws, pop the old one off and install the new, put screws back in and you're done...with the rotor part at least. As far as wires, Taylor's are supposed to be pretty good. I just installed some in mine but they haven't been in long enough to make a review. Check out synergyoffroad.com, a site run by a member on here. They are eightysomething bucks for a set.

 

Replacing the cap and rotor is easy. I just did it this weekend. You're really talking about four screws, and the usual issue of making sure you know where each sparkplug wire and the coil wire belong. I just bought my '98, and it still had what looked like the original cap and rotor on it. The rotor was especially nasty at 100k. Most of my wires decided to disintegrate instead of popping off the sparkplugs. Yours may be in better shape though.

 

Okay, I will look into all that. Thanks for the tips. How hard is it to change the spark plugs. Is is just better to take the blazer to an shop and have them change them? I was looking at them, and they look hard to get to.

 

They are easy to get to...through your wheel wells. Just make sure you have an extension and universal and it'll be a piece of cake. Oh, take your front wheels off when you do it to make it easier.

 

AC Delco is the way to go. My Blazer is just over 100k miles, and I just had a tuneup done. Costly, but the parts were expensive, not the labor. Do it yourself, if you have all day, a lift, plenty of patience, and something to break when you get pissed off. Mine has had a bit of a rough Idle for a while also. I have replaced the fuel pump, but that didn't solve the problem. I heard from a mechanic friend that the injector assembly (the spidery looking thing on top of the engine) is known to crap our after 80k or so. I am thinking about having that replaced soon. For a new cap, rotor, plugs, wires, fuel filter I paid a little under $500. AC Delco parts are not cheap.