Rough Idle

freddie cosme · #1 05-01-2005, 07:09 PM

I have a 1998 Chevy Blazer with a 4.3 vortex 6 cyl. My problem is I am getting a very rough idle or stumble. I replaced plugs and wires and the problem still exist. I even went through the trouble of pulling the new plugs and check to see if I cracked one putting them in. I also cleaned the throttle body and connected my snap on MT2500 scanner. After going through the diagnostics there are no codes present. I even tapped on the MAF sensor and it does not affect the stumble at all.Any one ever have this happen to them???

blazee · #2 05-01-2005, 07:12 PM

Did you change the cap and rotor?

blazee · #3 05-01-2005, 07:25 PM

If you didn't replace the cap and rotor, that is probably your problem.

You can also try cleaning the EGR valve and running some Techron through the tank.

BlazerLT · #4 05-01-2005, 07:27 PM

Replace the PCV valve also, it will cause a rough idle.

Fuel and air filter too.

freddie cosme · #5 05-01-2005, 07:58 PM

At the risk of sounding like a total IDIOT I have to ask..... I thought this particular vehicle was distributorless?

blazee · #6 05-01-2005, 08:05 PM

Nope, it's got one. If you replaced the wires yourself, you plugged them right in the cap. That needs to be replaced as well as the rotor inside of it. You can get an AC Delco cap and rotor from rockauto.com for a decent price. (that's where I got the ones for my 98 Blazer.)

freddie cosme · #7 05-01-2005, 08:10 PM

I see were the plugs wire go but I thought it was the coil assembly in a DIS system..... I am an IDIOT!!!!!!!!!!! LOL

blazee · #8 05-01-2005, 08:18 PM

Quote:

Originally Posted by freddie cosme

I see were the plugs wire go but I thought it was the coil assembly in a DIS system..... I am an IDIOT!!!!!!!!!!! LOL

Don't feel bad a lot of people have come to this forum believing they didn't have a distributor.

The DIS is on the 2.2L S10s
Yours has EDI. (Enhanced Distributor Ignition)

freddie cosme · #9 05-01-2005, 08:25 PM

Thanks.........Boy was I misled!!!!

blazee · #10 05-01-2005, 08:33 PM

You're welcome.

The screws have Torq heads. You will need a T-20 for the cap and a T-15 for the rotor.

BlazerLT · #11 05-01-2005, 11:09 PM

Quote:

Originally Posted by blazee

You're welcome.

The screws have Torq heads. You will need a T-20 for the cap and a T-15 for the rotor.

And watch you don't overtighten them or you will strip the threads out of the distributor.

They are only plastic. Tighten till firm and snug ONLY.

freddie cosme · #12 05-05-2005, 02:40 PM

I still have the rough idle after replacing the cap and rotor rechecked to make sure i did not screw anything up and it all looks good any have any ideas??

blazee · #13 05-05-2005, 03:11 PM

A rough idle has several common causes:

Some other routine maintenance items that can help are:

Air Filter
Fuel Filter
and PCV valve

Another common cause of a rough idle is carbon build up in the EGR valve:

Simply remove the valve, clean it, and reinstall with a new gasket.

In your other post you said you cleaned the throttle body. This may be another surprise to you...the throttle body only lets air in. You have an injector system located inside the intake manifold. It has six injectors one for each cylinder. The fuel enters the cylinder through a poppit valve. These valves are known to clog and cause a rough idle. The most effective way I know to clean them is to add a bottle of Techron to your fuel tank.

BlazerLT · #14 05-05-2005, 05:43 PM

Quote:

Originally Posted by freddie cosme

I still have the rough idle after replacing the cap and rotor rechecked to make sure i did not screw anything up and it all looks good any have any ideas??

What plugs are you using?

freddie cosme · #15 05-06-2005, 12:47 AM

[quote=freddie cosme]I still have the rough idle after replacing the cap and rotor rechecked to make sure i did not screw anything up and it all looks good any have any ideas??[

What do you recomend to clean the EGR?? Brakeclean??

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