Help!
1999 ford ranger xlt with 4.0 OHV
PULLING A CODE P-0171 LEAN BANK 1 WITH A PENDING CODE P-0174.
END OF EXHAUST SHOWS SUPER LEAN ,GRAY COLOR.
THIS JUST STARTED ON APRIL 16TH AND ENGINE STARTED MAKING A LOUD TYPE SUCKING NOISE.
ENGINE IDLES FINE ,BUT WHEN REVED, SOUNDS LEAN AND NOW HAS SLIGHT HESITATION WHILE DRIVING.
IM NOT RICH BY ANY MEANS, SO ASKING FOR HELP
THANK YOU, JERRY

 

The lean codes and loud sucking noise probably mean exactly what you'd expect - an air leak. Start looking for a broken hose or torn intake boot.

 

could it be anything else?

 

Ive been reading up on the 0171 code on the '99 4.0 OHV , and it sounds like it could be alot.
I no longer have a,shop or garage, so outside doing this, I hear intake manifolds leak. Vehicle is high muleage, 229,000

 

Welcome to the forum

Turn Cap Lock OFF

First, Lean or Rich codes DO NOT MEAN engine is actually running Lean or Rich, so your exhaust is normal

These codes mean the computer's air:fuel calculations are off and in the case of Lean it means computer is having to open fuel injectors longer than it calculated to get balanced O2 oxygen levels on that bank

P0171 is lean on bank 1, bank 1 is the passenger side of the engine, bank 2 the drivers side on V6 or V8 engines

Since you don't have P0174-lean bank 2 as well, then could be lower intake vacuum leak, or there may just be a delay until P0174 shows up

You hear a noise with engine running, so you will need to track that down, its most likely a vacuum hose that has come off or is leaking

There are 3 reasons for Lean codes
Vacuum/air leak
Dirty MAF sensor
Low Fuel pressure

Only the air leak will cause a noise so that's where I would start looking

You have a 4.0l OHV engine in a 1999 Ranger
On the drivers side of upper intake is the Vacuum Manifold, lots of hoses plugged in there, with engine running unplug each hose and put your finger over that port, see if engine RPMs change

PCV Valve hose is a common leak, it duns down to the PCV Valve in the top of valve cover

The 4.0l OHV's lower intake bolts can loosen up, they are just snug tight, 14ft/lb so if one gets loose it can cause an air leak on one bank of the engine

Also when engine is cold check O2 sensor on the passenger side exhaust, it can get loose and cause a false lean

 

what is turn cap off?
Also found vacuum lines that,are plugged off, right under the,air filter box ,Have no idea what,was there. Also in same area was a open vacuum line.
Will the gas thank canister solenoid, which was just replaced is where I found most of the very loud hissing sounf is coming from.
Would this give a bank 1 lean ?
And, sorry ,I sound like a idiot. Thought I knew my cars, It does have a pending 0174 code
Ughhh

 

On your computers keyboard

 

Follow any suspect vacuum line, like the canister solenoid line, to the intake manifold, and unplug it then plug that port so no leak, then see if "hiss" is gone after startup

Any vacuum leak can cause 0171 and 0174, but if you have both then its an upper manifold vacuum leak(shared by BOTH sides of the engine) not lower manifold vacuum leak, i.e. loose bolts

 

seems I fixed the vacum problem,
Thanks
Now another problem.
hopefully you or someone reading this can help.
​​​​​​​engine goes back down to idle normally, but spark advance takes forever. Idle, advance stays at about 24° for a few, rough idle, then about 30 to 40 seconds latter, will slowly come down to 10° and smooth idle.
why is it sitting at high idle for a few before coming down.
Please tell me it something simple. Only problem left.
Thanks to all who reply in advance
​​​​​​​Jerry