Solved: 2002 Ranger idle problems; oxygen sensor codes; bank 1 & 2 lean

Howdy all:

Intro:
I am VERY new to this forum but posting this for the sake of building a reference for future searches with these problems. I think I came here at a bad time. As I understand it, TRS.com is going to lose all of it's archived posts which were used to search past posts that could solve a problem. If that is the case. Let me post my problem so that others may be able to find some direction in the future.

The truck:
2002 Ranger 4.0L SOHC 80K miles
The Problem:
I had a check engine light come on. I took it to autozone and they said the codes read that the o2 sensors were bad and reading lean. ARGH, if I could go back to that day, I would have saved a $100+ dollars! As it happens I bought and replaced the TWO O2 sensors they said were bad.
(I could go on about the sensors I bought, one was before the catalytic converter and one after, the guy at autozone didnt know there were THREE O2 sensors on my truck.)

Moral of the STORY:
Dont trust check engine lights codes entirely. My gut instinct was 'how can TWO O2 sensors go bad at the same time'??? THAT should be a clue to anyone that goes to an auto parts store to have their codes checked. (I previously owned a Dodge Dakota with an intermittent electrical problem so I am no stranger to throwing money at a problem and hoping it goes away! I should have came to TRS and posted the problem here first!!!)

The Grand Finale:
My brother and I did a tune up on my truck before a long road trip. Everything was fine afterward. About 200 miles into the roadtrip the check engine light comes on. I have it tested at a different autoparts store and AGAIN they are saying it is the oxygen sensors! I say BS two of the three are brand new!

I continued on the road trip and noticed there is no difference in gas mileage, but the idle is running high. Like if I downshift to 2nd gear at 25 mph the rpm is running at 3k! I fix the problem by shifting to neutral and gunning the engine until the rpm comes back to normal.

While on the road, I contact my brother and he suggests something else could be triggering the bank 1 and bank 2 lean codes such as an IAC sensor, or a vacuum leak. He is right on! When I got back and checked it further sure enough we found a vacuum leak. It was in the corner of the vent line for the pcv valve. (If you guys want pics just let me know!)

Anyway, even with an electrical tape fix the idle on my truck resumed to normal and I havent faced the idle problems again. I havent put a lot of miles on my truck in the meantime but finding a vacuum leak and fixing it is very encouraging!!

Last but not least, IF you encounter this problem, I totally lucked out and had a guy at the Ford Parts center find a part that works for a lot less $$$. The part number is 3w7z-6853-aa. It costs $17 verus the $32 for the entire vacuum line, plus you get two of the corner vent hoses-they are not a precise 90 degree turn hose like the original but they still work.

I hope this eventually helps someone.

Cheers!

-Brian

PS A link to the location and part is here...


http://img.photobucket.com/albums/v228/pdxchump/DSC_0033a.jpg

Edited to add photo link.

Thanks for your post. I was headed toward the O2 sensor also. Past troubleshooting other vehicle experience was pointing that way. This is the first Ranger I've owned. Hope I can repay the info someday for someone. cmc

Thanks for posting RedRider. That's good info, and it will help others down the road. Codes are kinda like a huntin' dog; it'll point you to the right tree, but you gotta bag the critter yourself.

On the newer versions of ODB2 (I wanna say 98?+) there are a LOT of codes...

the cheap scanner that is used at schucks, autozone, etc, only pull the main 'code', but if you have a better (read MUCH more expensive) reader, you can pinpoint a lot better what the cause is. It's still not perfect (IE, it'll say Main code:XXXXX, then list the things that could cause it for that particular problem)

Sometimes it's worth it to pay someone with a SnapOn Modis reader or equivilant :grin:

Great post, should help a buncha people in the future

yep. excelent post............

Thanks for all the replies! You encouraged me to write about my serpentine belt problems. Apart from those two things I am no good to this forum!

Cheers.
-Brian