Rough Idle

[ICrushedAPrius]

I'm almost positive it is your IDLE AIR CONTROL. It's common for Expy's and especially Excursions to need this replaced. It cost me about 300 bucks to get done.
Your idle air control will vary your RPM's depending on weather (cold/hot) fuel used, etc. By adding/restricting air flow to make the fuel/air mixture leaner or heavier.

 

[ICrushedAPrius]

I'm almost positive it is your IDLE AIR CONTROL. It's common for Expy's and especially Excursions to need this replaced. It cost me about 300 bucks to get done.
Your idle air control will vary your RPM's depending on weather (cold/hot) fuel used, etc. By adding/restricting air flow to make the fuel/air mixture leaner or heavier.

 

[ajspellm]

Well just got it back from the shop and they say that both bank 1 and 2 are running lean. They are quoting me $875 to replace the intake plenum. They say that they are made of plastic and tend to warp over time and it needs to be replaced. Does that sound correct or is there something else cheaper that could possible be bad?

 

[ppeck]

Lane24 Rough Idle

I would like to thank Lane24 for the valuable information on that hose.
My 2003 Expediton started missing and had a rough idle and stalled a couple of times.
Took it to Autozone and had them hook up their obd reader. Codes po171, po174, p2195, and p2197 popped up on the reader.
I cleaned the MAF and had no change. Put in fuel injecter cleaner and had no change.
Looked on this site and found Lane24's thread. It took a little while to find the damaged elbow but shure nuff that was the problem. Thanks again

 

[stang99gtv8]

Had exact same problem with mine last winter. PCV valve and hose was replaced for like $50, good as new.

 

[gwinnch]

Lane24, thanks for the vacuum leak heads up. Found a cracked rubber connector between the pcv and the heated air inlet adaptor (i think) on the passenger side of my throttle body, and replaced it with a 2" section of 3/8" id radiator outlet hose i had floating around...i'll let you know how that works. Found this thread searching codes P9600 & P9602. Have been getting P0171 & P0174 for awhile. More backstory: Got a P0305 & P0316 this morning before I found the vacuum leak. Going to run it now & see what codes I still have. 156K on the motor and 15K on the fuel filter. All plugs changed about 125K.
Wouldn't have found that vacuum leak, even though it was right in front of me, without your photos, etc. Lane24. Thanks! Stay tuned....

 

[Lane24]

Glad its helping.

 

[gwinnch]

Started right up this morning (had been hard to start) and has not thrown any codes after being started & stopped 4 times. Thanks again.

 

[webfeet69]

iaciaciac the sky is falling

Everbody is sayin iac, i disagree!11 my 02 was doing the same thing and one of first things i check is the mas. for 5 $ you can get a can of cleaner just for this. all you have to do is take off the air cleaner clamp and look in side and see the mas. before you go any further disconnect the battery. Then spray the senser inside the hose going to the throttle body. let the residue evaporate then reinstall and give it a try. mine was doing the same thing and this cure worked>

 

[Lane24]

I Don't think everyone is saying IAC, just one guy. I think we are saying PCV hose. IAC is common thing for shops to tell you who don't know about the 'elbow problem' . Yeah, I think the first thing most of us does is clean their MAF. I clean my MAF, or mas as you call it whenever I change my oil. It is talked about quite often in other threads related to these codes. But thanks for mentioning it here. Someone will def. make use of the info.

 

[napew2009]

problems

Here's a 100% cure: Buy a CHEV!!!! Ok I'm kidding. lol. I have an expy as well

 

[vtefire]

Ok please help. I have replaced everything on my 2004 Ford Expedition 4.6L, everything meaning, coils, spark plugs, EGR...runs a little better, but when it is cold outside it is difficult to start. Once started it runs with a very slight hesitation. I have hooked it up to a monitor, no codes and no check engine light. So does anyone have any idea. My expedition has over 123000 miles and has been running great since I changed the fuel filter and found out i had bad gas. A new one was installed and like I said at the top, replaced the coils plugs and the EGR as of yesterday. Runs strong when warm, with a slight hesitation when you give it gas. I refuse to take it to a dealer do to they want a fortune. Any suggestions would be helpful, thanks.

 

[Lane24]

Vtefire. Have you read the first page of this thread? Have you checked your vaccuum assembly, your IAC, cleaned your MAF sensor... or some of the other things mentioned. All good places to start.

 

[vtefire]

Yes I have read all the threads. I have checked all my vacuum lines but I have not checked my MAF sensor or the IAT sensor. I will check those. thx

 

[strokin393]

Ok my truck idles but has a miss to it so I unhooked each injector on pass side one by one and it made no dif, it ran the same. I did same thing on driver side and it did what it should do, idle down. I changed the 4 injectors and one of the coil packs on pass side and still the same. I changed fuel pump, plugs, filters, plugs, and cleaned maf, and tb. I don't know what else to check. The truck backfires when I start it after its already been running. I think because its not burning all the fuel. What do I check next? I already checked hoses for vacuum leaks and don't see any.

 

[strokin393]

And pass side exhaust covered with oily gas inside it pretty bad

 

[anjy834u]

well sensors are definitely important. do check them

 

[SC-Surfer]

OK, I have a 98 Expedition in the shop with the same problem. 4.6L Right side miss fires - Other mechanic is working on it. He went through all the same steps as you (It has been to 3 shops)

So we pulled the valve cover and what did we see? 2 rockers were sitting on the head. Placed them back on, drove it and same thing happened.

Not quite sure if its sticking valves or weak lifters. We did Seafoam the intake. Still ended up throwing the 2 lifters.

Only seen this once before on a V6 Jeep Liberty. That turned out to be a broken exhaust spring.

I would pull the valve cover and have a look. (Oh what fun Ford made that)

get yourself a LED flashlight at Lowes or where ever. Trust me, your going to need it to check the springs.

 

[METALLICA]

guys can you show me where the iac valve is located? i think my truck needs its iac some cleaning, tnx..

 

[Lane24]

Where the red arrow is pointing. The pretty silver thing. It's an old pic from before I got the body lift. Much easier to get a t now.