Greetings to all! This is my first posting, and I have a problem that is stumping me and my mechanic....I have a '94 Blazer with a V6 vortec, and it has started having a rough idle when I stop at a stoplight or sign, or have to wait in traffic. He said the EGR was clear, replaced the spark plugs, one wire that was burnt, spider assembly (it was leaking), the distributor (it was bad), and the fuel filter. Seemed okay for a day or so, but now it has steadily gotten worse. We cannot find any vacuum leaks. It seems like it should run like a champ, but it's more of a chump!! Just bought it over a month ago (everything seemed fine then, my mechanic even test drove it with me!). It has 105,000 miles on it, and I love it...if only it would run!!! What are some other ideas for things to check? P.S. A diagnostic showed NO bad codes![sm=headbang.gif]

 

Sorry, I haven't forgotten about you. My home PC is having issues. Actually my home internet provider is the issue, and they have to fix it. The info you seek is at home and I don't have it memorized yet. I will try to get you an answer tonight. Sounds like your mechanic covered the basics pretty well.

In the meantime here are a few things to check out.
Do you know if he tested the EGR solonoid? If it is defective it won't operate the EGR properly and could be the cuase of your problem. I would also check the temp sensor.
Does this rough idle happen all the time after it has warmed up, or only when the a/c is on?
Doe sit go away if you turn the steering wheel to full crank in either direction?
There are a few other sensors tied into the idle system.

Welcome to the site.

 

post so I get an email at home.

 

I'm not sure about the solonoid...I am taking it back to him tomorrow to look it over again so I will check on that. Turning the wheels in any direction, in any gear makes no difference to the idle. Idle is rough with nothing extra turned on, A/C, radio, etc. One interesting thing, I bought some injector cleaner and put in today and it seemed to smooth it out a little after driving it around, but it's still rough. Last time he checked he said the injector (injectors? I'm not sure how many I have!) looked fine, but now I'm wondering if it's worth getting replaced to see if it could be that. I don't know how you feel about the injector cleaners, and maybe it's all in my head, but it did seem to help a little, leading me to wonder about the status of the injector(s). On a slightly different tack, what manual would you recommend for the home mechanic? I had a Haynes for my previous Blazer, but need to update as this one is newer. Is there a better one out there for those of us that like to try some of this at home? Thanks for such a prompt response, I think I'm really going to learn a lot checking out these forums!!

 

Try a couple cans of SeaFoam. Follow the directions on the can, run one can through the gas tank, after you replace the fuel filter, and another can through the intake via the brake booster or pvc hose (read the can it tells you how to do it).

Just for ****s and giggles I would also change the air filter, or at least inspect it pretty good. Tell me you don't have a K&N!!!! If so, your problem might lie on your MAP/MAF sensor. The wire gets coated with oil and causes all sorts of issues, rough idle being one of them.

As for repair manual. Hanyes/Chilton do a decent job when your just learning. Forums like this can provide those extra tips those manuals leave out. Things like how to make removing a particular bolt easier, etc. For the past 15 years or so, and to this day, I still pull out my Haynes manual to see how to do stuff. Stuff I haven't tackled before. I have a Haynes manual for all my vehicles. Kind of hard to beat thm for as cheap as they are.

 

Thanks for the advice...I'll try the SeaFoam (does it matter if the fuel injector cleaner is still mixed in the full tank of gas?) and have my mechanic check out the air filter. This Blazer is so new (to me, anyway) that I haven't had much of a chance to poke around under the hood and see what's what. Even if I may not be able to fix it, I still like to know exactly what my mechanic is doing to my ride!

 

A new (and unexpected) development....Had to run out to pick up my daughter at a friends, and although the idle still seemed better, I noticed that there is now a bit of a whining sound in the lower gears as it accelerates. Also seems to "surge" a bit when coasting at the low end. Does this make any sense? Hopefully this is all related to the same problem, not anything new...

 

More info is always better.

Did the mechanic change the spark plugs when he changed thw wires. Rough idle could be from improperly gapped spark plugs. It could also be from the WRONG spark plugs. I hihgly recommned AC Delco plugs in our engines. The electronic ignition systems is highly tuned and operates in a very tight manner, having a similar plug is enough to cause performance problems.

Did you mechanic test the fuel pressure? Your new bit of information and the rough idle could be related to a fuel pump that is operating erratically. Did he check teh fuel pressure regulator? Almost the same result as the fuel pump.

Lastly, and I hope this isn't the case.
Torque converter. Typically a whine in low gears is from a failing torque converter. Make sure the tranny has the proper amount of tranny fluid in it. A failing torque converter can also cause a rough idle. Poor engine performance is the first thing to fix. Most tranny issues turn out to be engine problems. I suspect your issue lies in the engine (specifically the fuel pump or spark plugs), however keep the torque converter in mind.

 

that's beautiful. Want me to send you pm's every few days?

 

Just checked w/my mechanic-plugs are Delco, no K&N air filter (his wife has a Bravada the same year, same engine, so he is at least familiar with what you all have told me!). I will tell him to check the fuel pump and regulator (he still can't get any codes to show up but he agrees that it is running really off). Will let you know if we manage to find the problem, or if this is to be a continuing story...