04 4.0 Bank 1 and 2 lean

[D Hook]

idle air control

 

[Berky]

I have both 171 and 174. I replaced the fuel filter, cleaned the MAF. Still have them. What should I go to next?

Installed new plugs and wires. Went with Belden wires. I guess I'll check out the EGR valve next.

 

[jbizub5192]

I replaced my egr valve plus gasket and it is better but my Lt fuel trims are still near the +20s. I knew I had a leak in that area after using my diy smoke test. Where else can the vacume leak be? I have check all hoses and even replaced some of them. I know it is a vacuum leak because as I raise the rpm my fuel trims decrease. Being though I have an 04 it is a fully electronic throttle body with no separate IAC. Plugs and wires I doubt are going to do anything for me because I have no misfire codes. Although the codes are "lean" the engine isn't running "lean". It is actually running super rich. There reason why it says lean is because the pcm is adding more fuel due to a vacuum leak and therefore is out of parameter.

 

[mikeinri]

Run the smoke test again until you find the source. That's your best tool at this point.

Mike

 

[2000StreetRod]

fuel pressure?

Did you confirm the fuel pressure is 39 psi via OBD II?

 

[20EddieBauer02]

Bumping this up, I have an 04' xlt here with the same exact problem. 220k miles. Also has a lopey idle

 

[jbizub5192]

I wish I had a fix. It has been to cold here lately for me to look into the problem farther. I already did everything I could think of. I really need to run the smoke test again. I just keep my code reader on hand and keep resetting the code. I'm hoping to fix the problem within the next few weeks.

 

[mranderson214]

Bumping this up, I have an 04' xlt here with the same exact problem. 220k miles. Also has a lopey idle

Did you ever find a resolution for this? I have both P0171 and P0174 on my 2002 XLT V6 with a little over 230k miles.