P1071 and P1074 with rough Idle and stall

[csanch40]

Good morning,

I have an '04 XLT with the 5.4 2v. I recently got the P1071 and P1074 lean codes and a few days ago noticed a rough idle and eventual stall if left at idle.

About 6 months ago, I had a diagnosed coolant leak from the intake manifold. I ran some stop leak and that took care of the coolant issue. My guess is that the gaskets round the manifold are also bad which is throwing the code, and causing the rough idle.

Anyone else have experience with this? Other culprits? Vacuum lines? Time to get the new intake manifold?

Thanks for all suggestions.

 

[Plati]

check out that rubber elbow
$50 says it's the elbow
haven't lost on a $50 wager YET
https://www.expeditionforum.com/threads/obdii-reader.34543/

i had multiple problems on that thread but root cause was the elbow

 

[Hamfisted]

The only sure way to tell is using a smoke machine on the intake system. Other than that you'll just be firing a parts cannon at the problem. What was the coolant leak on the intake manifold? They are notorious for delaminating there where the cross flow attaches up front. It would not be unusual to replace the entire intake manifold with a new Ford part. But yes, check ALL the rubber elbows and fittings attached to the intake.


https://www.amazon.com/AutoLine-Pro...Mechanics+smoke+machine&qid=1600704007&sr=8-3


https://www.amazon.com/Ford-2L1Z-9424-AA-MANIFOLD-ASY-INLET/dp/B000NS1A8K/ref=sr_1_6?crid=2SDU1MIGHGNV2&dchild=1&keywords=ford+5.4+intake+manifold&qid=1600704236&sprefix=Ford+5.4+intake+man,aps,186&sr=8-6

 

[Jeff G]

I agree with Hamfisted. I had a rough idle and a P0174 code. Sprayed every hose and intake manifold and couldn't locate the leak. Had it smoke tested and found a hose I had checked and sprayed repeatedly had a slice in it and smoke poured out of it. That took care of the rough idle. The P0174 was a clogged cat.