PO171 & PO174 on 4.0 ohv

[Lou Colmo]

Codes PO171 and PO174 ( bank 1 & 2 lean ) showed up on my wifes 98 Explorer on the way to work today. I've seen the posts that talk about the recall with the sohc engine, But I take it those do not apply to the ohv. The fuel filter is 3 months old and it just got a new air filter ( standard type). Does anyone have any idea's ? Thanks in advance.

 

[aldive]

Take a peek at http://www.obd-codes.com/trouble_co...neric/p0174.php

 

[Lou Colmo]

Well I cleaned the MAF and reset the computer, The CEL didn't come back on untill the wife stopped for gas,So I replaced the gas cap and reset the computer again and the CEL came back on a few days later. From what I've read it could be a vacumm leak( don't see anything obvious ) or bad o2 sensors. Is there a way to check the o2's with a meter for resistence ?

 

[Billy177]

possibly loose intake manifold bolts do you have an sohc or an ohv your signature says ohc but the post says ohv

 

[Runnin'OnEmpty]

Lou, I agree with Billy and the loose intake maniflod bolts. You may have to replace the gaskets if re-torqueing the bolts dosen't help.

It's doubtful that you'd get lean codes on both banks, if the cause was faulty O2 sensors. A vacuum leak is more likely.

 

[Lou Colmo]

Thanks guy's. It has the noisey 4.0 ohv in it.

 

[Mike 97]

I am dealing with the same problem on my ranger. I also have an idle problem - starts up fine but the idle bounces from ~600 rpm to ~1000rpm. You can listen to the exhaust and hear a -pop- every so often. I am leaning towards a misfire problem. Is there a way to check for misfires using a scanner? Are there any common places to check for a vacumm leak?

 

[monkeydude3]

I have a 1994 4.0 L OHV and I hear that same popping noise... I need a new coil as far as I know (bad ass missfire)... For the lean 1998, my auto instructor has a 1998 ranger with the 4.0L OHV and his came up with THE SAME EXACT codes you encountered... we checked it all and found no vacuum leaks, but found one of the EGR hoses that go to the EGR tube to be considerably loose and I felt air blowing out of that... not sure if it was the fix as this was before winter break and then he left.... check the EGR hoses... also a simple way to check for a vacuum leak is take carb cleaner and spray it at places you suspect bo be leaking, if it changes your rpm considerably whether it be up or down, you have found a leak....take care!
GEORGE

 

[davidbaggett]

hey Lou, I am a newbie here, but my explorer is also throwing 0171 and 0174. Just wondering if you found the culprit. thanks

 

[Mike 97]

Thanks for the advice. I will have the time to look at my truck tommrow - will update with any findings.