Weird Idle

[Verse]

2000 Mountaineer.

I've noticed that on a cold start, while in park, my truck has a sort of weird idle.

it will idle normal for a moment, then idle high to low, high to low, high to low, repeat. Like it can't figure out what RPM it wants to idle at. I know cars frequently idle at different speeds when idling for long periods of time, but i'm speaking in terms of just a few moments.

i was wondering if it could be the IAC that needs cleaning. When my lincoln town car started having a weird idle, similar to this one, it wasn't long before the idler went out and i stalled at every other red light. cranked back up fine, however it was annoying, and many people flipped me off or leaned on their horns thinking i was dozed off at the wheel or texting and driving. But i'm just trying to see what else could be the problem.

I love this little truck. it's been pretty dependable so far.. so i wouldn't be surprised if it'll need a lil money put into it soon. Check engine light only because of an emission leak. Luckily i live in a state that doesn't do emissions tests.

 

[lobo411]

It's probably tied to your CEL and whatever code you've got, which most likely boils down to a vacuum leak somewhere.

 

[ZWilson07]

it's probably tied to your cel and whatever code you've got, which most likely boils down to a vacuum leak somewhere.

^2.

 

[Verse]

the code is P0442 - eval emission small leak

you guys think this could have something to do with it?

 

[koda2000]

it's sounds air related. as such, it could be the IAC (cleaning doesn't always work, sometimes it will) or a vacuum leak somewhere. usually, with a constant vacuum leak the idle will be high. get the CEL code and report back. which engine do you have? the SOHC V6 is more prone to upper intake manifold gasket/o-ring leaks, especially when cold, and PCV elbow cracks.

 

[Verse]

it's sounds air related. as such, it could be the IAC (cleaning doesn't always work, sometimes it will) or a vacuum leak somewhere. usually, with a constant vacuum leak the idle will be high. get the CEL code and report back. which engine do you have? the SOHC V6 is more prone to upper intake manifold gasket/o-ring leaks, especially when cold, and PCV elbow cracks.

hi koda, the CEL code is P0442. The engine is 5.0 V8 with 116k miles.

 

[koda2000]

hi koda, the CEL code is P0442. The engine is 5.0 V8 with 116k miles.

P0442 is a vacuum leak in the evaporation system. it must be a pretty big leak to be causing stalling. your have relatively low miles, especially for a V8, so whatever the problem is it should be pretty obvious. have you had any work done recently? things to check:

gas cap
fuel filler and vent pipes/hoses for holes
line from fuel take to the evap canister over the spare tire
the evap canister itself
hose from evap canister to engine compartment
connection to purge solenoid (located under the batter tray)
hose from purge solenoid to the intake manifold

 

[ccm2001]

Open ur hood listen for a whistle try to pin point it. Just look at all the vacuum lines

 

[ZWilson07]

With it being in the evap system, it could be all the way back to the gas tank/charcoal canister area of the vehicle. Without having a smoke machine, or a way to monitor STFT/LTFT while using propane and such, it is going to be hard to find if it is in fact a vacuum leak.

Personally if it was me and I didn't have the tools, I would either be deciding to drop it off and a good local shop with a smoke machine to easily find the leak, or put the money into buying some tools and doing it myself. More than likely your best bet is going to be to drop it off at a good shop. If they have a smoke machine, they could find it in a very short amount of time and shouldn't be to much on labor.

Goodluck