: P 0171 and P 0174 code - 2004 Deville

08-07-13, 01:41 PM
171 and 174 code coming up on my 2004 deville. I have removed engine cover and sprayed starting fluid all around intake system especially rubber boots,etc. Cannot detect any air leakage. Is there something else causing these two codes to come up:helpless:

08-07-13, 02:01 PM
P 0171 and P 0174 are caused by large air/vacuum leaks in the intake ducting, intake manifold, or PCV dirty air piping - from the right (rear) cam cover PCV orifice to the passenger end center tunnel in the intake manifold. Your best bet would be to use a mechanic's stethoscope to snoop for hisssssses.

Did you shoot/listen down at the intake manifold/throttlebody connector plenum - the rubber boot and clamp that you can barely see ?

Cadillac Tech Tips in Discussions, Item Specific.

Bank 1 and Bank 2 lean fuel mixture codes

08-07-13, 02:59 PM
Spray at the bottom (6:00 position) of the plenum duct and flex it while doing so (engine idling of coarse).

08-10-13, 03:01 PM
You got it Ranger. Exactly at 6 oclock the plenum is cracked . Nothing strange would happen until I deformed the plenum with a little bar. Thanks for the help that warning was driving me nuts.

08-10-13, 03:33 PM
Plenty of manifold and plenum pictures in my albums.

Plenum and 8 intake manifold seals from RockAuto for $15 + shipping. The Dorman box.