[mpb]

Help,

Is anyone out there familiar with the 4.6 Northstar? Mine is prone to idle surge. Someone took off the plenum and I was wondering if I might be on the right track looking for a vacuum leak there or should I look toward the crank positioning sensor? Thank you.

Rabbit

 

[Krashed989]

The plenum? I've never heard that term used before... Are you talking about the intake manifold cover? That cover is the top of a large vacuum chamber, so if you were to not put it on right, you would get surgyness.

 

[Ranger]

Krashed is right. Probably a bad seal somewhere around the cover gasket. Your definately looking for a vacuum leak.

 

[addison_ii]

While you're under the hood you might want to check your ISC motor. It may need to have the contacts cleaned as well as the above advice.

 

[davesdeville]

I'm just curious, on the 93-94 intake manifold, is the top piece just part of the plenum area or the runners as well?

 

[Krashed989]

The runners are there to direct the flow of the air, but the they are not sealed. So I guess you can say the plenum is part of the runners as well.

Yeah I looked up the word plenum. Funny that out of all the time I've spent working on cars, I have never heard that term before.

 

[mpb]

Thanks for the feedback. Should there be oil in that area?

 

[Krashed989]

A little bit of oil in that area is normal. Don't worry about it.

 

[kls]

My '94 eldo just started doing that, surgering while ideling. I WOTed out a couple of times and it was OK. This all stated after not driving on freeways for about a month. It keeps coming back as long as I'm only doing city driving. Helps when it starts to surge throw it in park and rev the rpms. I was thinking maybe dirty fuel injectors? :hmm: