390 Rough Idle

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Mar 24, 2011 | 04:11 PM

#16

lonnie1952

Senior User

Joined: Aug 2010

Posts: 113

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From: Moreno Valley

Quote:

Originally Posted by pit_of_pity

How would the canister purge cause bad idle. I thought that this can be an issue with newer models.

http://i69.photobucket.com/albums/i7...tivesystem.jpg

Not the Purge can...The vacuum canister...if your truck is pretty much unmolested you have a Vacuum canister mounted on your driverside fender..Looks like a Soup can. It is there to hold vacuum to operate your dash switchs and such..if the hose is off..or has a leak you will get a bad idle

Looks like a SOUP CAN...under your master cylinder on the driverside fender
Has a vacuum line going in and out of the can. Worth a Look.......

Lonnie

Here is a pic

Mar 24, 2011 | 04:45 PM

#17

pit_of_pity

Thread Starter

Senior User

Joined: Nov 2007

Posts: 120

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From: New York City

I see. My truck was molested apparently. I don't have that feature. I do notice that the truck idles much rougher when connected to ported instead of manifold.

Mar 24, 2011 | 04:50 PM

#18

lonnie1952

Senior User

Joined: Aug 2010

Posts: 113

Likes: 0

From: Moreno Valley

Quote:

Originally Posted by pit_of_pity

I see. My truck was molested apparently. I don't have that feature. I do notice that the truck idles much rougher when connected to ported instead of manifold.

Ok here is a Old mech's way of finding a bad idle due to a vacuum leak
Get a can of carb cleaner with the red tube...Lightly spray small amounts
vacuum hoses..intake mounting carb mounting..throttle shafts.
if you find a vacuum leak the engine will smooth-out..maybe speed up

Lonnie