Hi, I have a 2000 4.0. A couple weeks ago i got po171 and po174. I read on here that it could possibly be a leak in an elbow on a vacuum hose. I can not find that hose and elbow for the life of me, I have searched for hours. I've looked at other diagrams for other years and engines, all they're all different from my engine compartment. I cant find any diagrams for my year. Any help or knowledge of diagrams would be much help.
Thanks!

 

If it is the PCV hose, check drivers side at the rear of the valve cover. short s shaped hose connection the intake to the PCV.

 

I checked that i didn't see any tears or holes in it.

 

One way people here have indicated to find leaks is ... Spray Carb cleaner, ether/engine starter fluid, in light bursts around the top of your engine, near the manifold, hose connections, where ever you see vac lines, or manifold connections, while the engine is running. Any pick up in RPM's will indicate a possible vac leak. you may find that hose this way.

 

Thank you, I'll try that and get back. thanks

 

Took me along time to get back but I've tried all the things to find if i have a vacuum leak and come to the conslusion that it must be something else causing the codes. So what else could be going on that are causing lean 02 sensor bank 1 and 2 codes. I've cleaned the MAF already. thanks!

 

Possible ... Low fuel pressure (pump weak or clogged, filter clogged) Bad O2's (not likely lose both upper O2's at the same time) Third O2, down stream sending wrong signal confusing ECM. Other sensors sending wrong info to ECM.

All these possibles require testing of each sensor and fuel pressure, to see if they all fall in Manufacture's parameters. Not an easy nor quick task. But there are vids posted to guide ya thru this.

I bought a OBDII program that works thru my laptop, giving me real time reads on all sensors and engine data. Not only gives me codes, it explains those codes and possible solutions if I enter that data on a website.

Good Luck, lets us know how your doing.

 

I just went through this recently and tried quite a few things. Drove fine so not a big rush. I changed my upper intake gaskets and codes were gone. They would show up when cold and started last winter. When they came back this fall I started to slowly check all the usual suspects.