Rough idle? P0171, P0174? Here's what you need to check first!!!

[adamal87]

I have same rough idle symptoms

Same symptoms, but different codes. P0356 & P0358. Cylinders 6 & 8 are missfiring. The dealer wants to compleatly replace the 2 problem ignition coils, remanufacture the boots on the rest, & replace all spark plugs. With a wonderfull price of $950. I know I have some options, so what do you guys suggest? I can get a pack of 8 coils at autozone for $120 & we all know how cheap plugs are. Its the labor cost I fear with this one.

 

[tallsville]

adamal buy the coils and plugs yourself(look on ebay, i just but 8 cops for less than $100 and plugs for $35). you can replace them yourself but can be pita. if thats all you're doing is plugs and cops, try and find a small mechanic, no need to go to a stealership. shop around.

 

[adamal87]

Thanks for the advice Tallsville! I ended up getting 2 complete coils & 6 boots for $140. Got the labor done for $130, so I didn't get as good a deal as you, but under $300 for the whole job will work for me.

 

[McNally]

hey

just had these codes pop up on my 2000 Expy XLT. I'm going to look into the vaccum leak. What i am concerned with is a noise. It sounds like a "rattle" only when its running. You can hear the "rattle" cease when you shut the motor off. the noise is around the r/s (pass) valve cover. is that the sound the pcv valve makes? looking to cover all of my bases here. thanks in advance. great original right up....very helpful

 

[Big Red Monster]

ok so i did some checking on my engine and the infamous elbow seems swollen and possibly cracked. Im going to replace it, but the hose its connected to has insulation around it, is this the heated version of the assembly? also seeing as its all plastic i had an idea, Ill make a new tube out of aluminum, steel or copper tubing, is this a good or bad idea?

 

[Big Red Monster]

fed up with all mechanics. ordered the elbow and a new pcv valve from O'Reilly auto (motor-craft brand of course), going to change them out tomorrow. I also cleaned my Mass air flow sensor today, seemed to help out a little bit but Im changing the elbow just because between all of you and the F150 forum it seems I have a 95% chance that the elbow will solve the code so wish me luck!

still considering if I should make a new line out of cooper tubing, waiting on your responses.

 

[Big Red Monster]

replaced the whole damn assembly from elbow to elbow, truck idles a little smoother now, gonna see how it runs the next few days. the elbow was collapsed on the inside

 

[Circa1981]

Glad to see this thread revived!

This just started happening to my 2003 4.6L Expedition.

Runs fine when cold. Once warm, the idle drops and stays low. If I give it gas it will die once I take my foot off the pedal. So far it has only died at stop lights and slow turns, or when sitting in park, never while moving.

Today I tried to pull the hose that runs from the pcv valve to the intake, but I could not get it off. Is there a secret to getting it off the intake? It came off the pcv valve really easily but I could not pry it from the intake in the back near the firewall. I think I actually squished it and I noticed later when I started it back up that the elbow has extreme suction on it now when I start the truck. Is that normal?

It felt fine as far as holes and I am not sure if that is the problem. I didn't notice the idle change when I played around with the elbow back there.

The code I am getting is P0506. It says it's the idle air control. I realize that's a generic code though.

My plan is to clean the MAF sensor, replace the pcv (both cheap) and the idle air control valve and possibly connector and continue searching for a vacuum leak with fingers crossed.

Anyone have any suggestions?

 

[Big Red Monster]

Mine was kind of glued to the manifold lmao. What u need to do is using a small screwdriver push the elbow back and then while pushing back wiggle the elbow it will pop right off. Installling the new one will be easy. I also cleaned the area the elbow attaches to with MAF cleaner

 

[sergt]

ok guys i've got the same P0171,P0174 on my, change MAF,O2 sensor's, finally change PVC line, got rid of P0174 but still have same symptoms and still have P0171. So far it has only died at stop lights and slow turns, or when sitting in park, never while moving. Any suggestions?