Hello,

I am in the process of diagnosing a rough idle / hesitation when cold problem.

Have already found a lot of useful info here. Thanks!

There is a clicking sound coming from a part on the right (pass.) side of the upper intake plenum. It is cylindrical, has an electrical connector on top w/ 2 wires, is right next to the MAP sensor and appears to be held in place by two of the studs holding the plenum.

I think it is the purge solenoid, but am not sure. Can someone confirm or deny?

The solenoid clicks intermittently when the engine is idling (it idles rough). I almost mistook it for a rocker arm tapping. The idle smooths out when the engine is warm, and the clicking becomes rapid and constant. Is that normal? Does this part typically need cleaning or replacement?

Thanks for any insight.

Franco
2002 Blazer LS 4.3
125,000 mi.

 

jus wondering if you ever figured it out? im having rough idle problem too. never noticed the noise though.

 

I've done a lot to the Blazer since I made that post.

The problems I was experiencing at that time were caused by a worn distributor drive gear and a burned spot on the coil. I also replaced the ignition wires while I was at it.

The truck was running great, then threw a code when the weather started cooling down. It was not reaching full operating temperature because the thermostat was stuck open. Since I would be draining the cooling system anyway, I decided to replace the lower intake manifold gaskets along with the thermostat. They had leaked a couple of years ago and I put in a can of Bars Leak... I knew they wouldn't hold forever, and I'm glad I replaced them. When I got the manifold off, I saw that the gaskets were a soggy mess...

While I was at it, I installed the upgraded fuel injection spider that I bought from a member of this list. This is a great resource!

The truck is running like new, but recently threw the P0440 code, so I'll be looking at the evap system again. Yes, the part I mentioned is the Vapor Canister Purge Solenoid. I cleaned it when I had the intake apart, but haven't looked into it further. The truck runs great and it's cold outside...

Re: your rough idle... I'd look at ignition causes first. How many miles are on it? Have you replaced the cap, rotor, wires, etc? Are you getting any codes?

peace