My 97 Ranger with a 4.0V6 with 120,000 miles, was dieing at stops so I cleaned out the throttle body and the IAC. The dieing issue stopped but I was getting a roaring through the air intake. It sounded like a vacuum cleaner roaring. Nothing seemed to be obstructing from the air cleaner to the throttle body. It also sounded like it could be in the intake manifold. I finally unhooked the Air intake at the throttle body while it was running. After the truck died I started it back up and it sounded a little better but it was still there. Anyone have any ideas what is causing the roar?

 

Air leak somewhere, check around the intake manifold.

PCV fitting, tubing or fittings.

 

I checked all the vacuum connections I could find and nothing was leaking. I thought maybe it could be leaking around the IAC connection but it seemed tight. I will have to check it again.

 

Replace the IAC. The motor is messed up and the howl will go away.

 

The howl finally went away when I pulled the air intake off the throttle body. Now we have a surging that causes a stall sometimes at stops. Could it still be IAC after I cleaned it? It always starts back up.

 

The IAC is working but the motor in it is shot. The motor is causing the roar. It stops with the air intake tube off because the tube is resonating the sound from the motor. It took me awhile at work to trace it down on a couple of our rangers but that is what stopped the roar. Or howling as it sounds. Good luck.

 

I should clarify that when I pulled the air intake off the throttle body the engine quit. After I put it back together the howling or roar went away and did not come back. Could this surging be related to a possible bad alternator?

 

I replaced the IAC and it worked fine for a couple of days then the check engine light started flashing and the engine started missing and died when you put a load on it. Could it be the MAF sensor or something else. I am going to try to get it to Advance to get the codes pulled.

 

Codes pulled were:

P0171
P0174
P0301
P0302
P0303
P0306

 

The first two mainly have to do with an air leak after the MAF like

I mentioned in post 2 or a bad MAF(replace only as last resort).

These can be hard to locate.

The rest are misfire codes.

Check your plugs and wires.

With that many cylinders misfiring, check the coil.

When driving the truck does it stumble under load (as in going up hill), does the CEL flash at that point?

 

The truck usually stumbles at stops. I was checking the truck out at idle and it started flashing and backfireing some then smoothed out. I assume that is when the first codes appeared. I managed to get the MAF out but I could not get the sensor separated from the housing so I used some q-tips and electrical contact cleaner and cleaned the sensor in the housing as best I could. It did seem to help when I restarted it. It did try to stumble but the new IAC kept it from quitting. One thing I did notice was the egr was very rusty. I did not find any holes in the egr pipe to the intake but I could not tell if there was any holes in the rusted egr valve. I also noticed no vacuum in the hose connected to the egr valve, should there be? I have checked all the vacuum hoses and PCV and cannot find any air leaks.

 

Update 1997 Ranger 4.0 v6 121,000 miles: I finally got a good cleaning done on the MAF. I checked all the spark plugs except one that I could not get out, I was trying not to create another problem. I will hit it with PBblaster and try it later. All the plugs appeared to be good so I checked gap on them and put them back. I pulled the negative terminal off to clear all codes. I drove it around until the check engine light came back on. It had been iding a little rough @ 750 rpm's when in gear. IAC is keeping it from dieing. I also runs rough under light loads and at cruising speeds of 35 mph and 55 mph. Acceleration is good. I have checked and double checked for vacuum leaks and have found none. Went to Advance to get the codes. They are as follows:

P0171 - Lean
P0174 - Lean
P1311
P1511

Everything seems to point to O2 Sensors now. What do you all think?

I almost bought plug wires but they were not in stock, so I did not buy them for now. Would they help maybe?

Funds are tight now and I do not want to throw parts at it.

 

We are not supposed to clean MAF sensor wires with qtips,

There is a sensitive coating on them, this could be why

You have metering codes now.

Check your fuel pressure.

Then double check for air leaks

Oil cap
PCV
Intake Manifold gasket
Injector o rings

P0171 and P0174 are leading to Air leaks,

The O2 sensors are dealing with poor fuel mixture.

 

I was changing the EGR valve and managed to get the 2 mounting bolts loose with out breaking them. The ends of the bolts that stuck through the threads were so corroded I never thought I would get them out without breaking them. They must be different sizes because I used a 3/8" socket for one and a 10mm for the other. I am going to see if I can find replacements. The problem I ran into was the fitting that is bolted into the EGR. It is so corroded I don't know if I will be able to get it out without rounding it off. If the fitting can not be replaced it looks like the pipe that runs from the EGR to the exhaust will have to be replaced. Does anyone know what that pipe is called? I can not find it on the online parts catalogs. It got dark on me so I am down until tomorrow.

 

Few years ago when my Sable threw a P0171/P0174 code, I found a split in the PCV hose.

Found this interesting site a while back.

Ford P0171 & P0174 Lean Codes