greetings to everyone,

I've been a member for a while now but only lurk when I need info. and for that this site has proved to be very useful.

now I'm at the point where I need some help. I have an '04 F150 that has started having some idle issues as of yesterday. it has stalled on me twice but only when the a/c is on. it also has an erratic idle with the a/c on. once I turn it off idle is smooth. it only stalls when I'm at a stop with the a/c on, not when it's in motion with the a/c on. but like I mentioned above, it has only stalled twice, but the erratic idle is there always when the a/c is on.

where do I start? can anyone help? I'm ignorant when it comes to these newer Ford engines. any help will be highly appreciated.

--carlos

 

Sounds like a failing TB! Try cleaning it! When was the last time the spark plugs were changed out? Fuel filter?

 

by TB do you mean throttle body? what exactly can fail in a throttle body?

 

The throttle body in these trucks are all electric! It's a drive by wire system and the electronics in the TB have been known to fail. But a good cleaning with TB cleaner can help. You must remove the TB from the truck before cleaning.

 

ok, point taken. I'm assuming this is the best case scenario, what would be the worst? this is also the 6cyl model, if that means anything.

 

Add a full vehicle signature so we can further help you! I gave you the info for the V8 engines.

 

Any codes?

 

info on the truck is as follows:

'04 F150 4.2L V6 about 103k miles on it.

just got back from the local AutoZone and they pulled the codes for me. the only one that came up is P0506

can you guys help any further?

 

Check this link...... P0506 Idle Air Control System RPM Lower Than Expected - DTC Code

Probably just a good cleaning is needed.

 

thanks for the link. sheds a lot of light on the situation.

when taking the throttle body off, does the IAC valve have to be removed from the TB for cleaning?

 

I don't think you have an IAC, but if you do, that is better. Not sure when Ford stopped installing. Remove the IAC and clean it good. Soak the inside of the throttle body to clean it as well. You don't need to remove the throttle body to clean with spray. Remove the little red hose that comes with the TB spray as you don't want it to fly off and into the TB.

 

how can I make sure if I do or don't have an IAC?

 

FYI never clean the TB with it on the engine! The plastic intake manifold starts to dissolve with the cleaner.

 

Trust me, I'm all about taking care of our vehicles, but do you have proof in the chemistry that throttle body cleaner ruins plastic manifolds or are you making random statements that have not been proven in your lab?

Please show your lab reports that support your statement or any FMC lab supporting statements concerning plastic degradation and feel free to copy and paste your report here. I anxiously await your reply so I don't jack up my trucks.

Thanks,

John

 

Mine is acting very similar to Pony's. Rough idle and stumbles/stalls at low engine speeds like stop lights and turning into the driveway. Can't use the a/c except at highway speed.

I have not had a chance to get the codes on it but will tonight.

Anyway, I replaced the fuel filter (very dirty!), air filter and spark plugs. The air filter was not terribly bad and the spark plugs were not fouled but looked somewhat lean with a lot of erosion and pitting on the electrodes and straps. The engine starts easier but the problem is still there.

I was going to clean the throttle body but the Haynes manual suggest not cleaning with a spray solvent as the throttle body and it's components are coated with a substance that is to prevent crud from sticking to it. So, I didn't clean it.

The engine is a 4.6L with 80,250 miles on it.