08 Ford Fusion Idle Rough (rat nest in air cleaner!)

[wolfehunter]

My daughter's 2008 AWD Fusion with 3.0 V-6 and 130,000 miles is idling rough and occasionally is stalling. Last week she called me and told me it was "bucking" while going through the drive thru and the check engine light came on. First thing I did was check wiring and then the air cleaner. Sure enough there was a large rat nest built in the air cleaner with bird feathers, corn husks and the like. I know it was a rat because a few days before this happened I shot a rat with the BB gun that the dog chased up under the car. It was behind the motor near the firewall and I was very careful not to shoot any vacuum lines off although I second guessed myself when this idle problem started and double checked all the lines........all were good.

I checked the codes and they were P2195 and P2197 which are both O2 sensors which I'm thinking threw the code because it was running lean not getting enough air so the computer was dumping extra fuel causing a rich condition? She normally gets 25 mpg and I checked her odometer settings and she has only been getting 15 mpg. I replaced the plugs with Autolites, installed a new air cleaner, cleaned the throttle body and mass air flow sensor and checked for vacuum leaks. Cleared the codes and runs great. Gas mileage is back up to 25 mpg but still idles terribly and sometimes stalls. I can't even do the recommended idle relearn procedure after cleaning the throttle body as it won't stay running. It "lopes" like it has a big cam in it and if you put it in gear while idling it bucks. I notice that if I put the air conditioning on while in neutral it idles fine so odd it would do that under load. And it does run fine otherwise without a hiccup. Check engine light hasn't come back on yet. Fuel injector go bad? There is no idle air control sensor to replace on these as they are built right into the throttle body. I am thinking this is RAT related!! Any thoughts? Thanks, Scott

 

[wolfehunter]

Forgot to mention I added a bottle of Seafoam to the gas tank to try and clean up the injectors if it was needed.

 

[Lolvoguy]

Did you try disconnecting the battery for a few minutes?

 

[mk378]

Look for chewed hoses or other air leak anywhere after the MAF sensor (including before and after the throttle body). Running worst at very low air flow then getting better suggests there is a leak of unmetered air.

Also look for chewed wires everywhere. There will almost certainly be chewed wires, they may not actually be completely shorted or broken yet though.

 

[clinebarger]

What are the Fuel Trims doing? If they are high at idle & correct under load....Suspect a vacuum leak. If they are high under load as well.....Suspect the Mass Air Flow or Fuel Pressure.

Take a good flashlight & inspect the MAF for debris across the resistors, I know you said you cleaned it, But you need to visually inspect it!

 

[wolfehunter]

Yes, disconnected - battery terminal and ran jumper wire to cables to clear computer. MAF looks good and recleaned it.

Friend of mine told me wire insulation has soybean oil in it and that the rat may have chewed off O2 sensor wires? Will crawl under tonight and look things over. Will report back. mk378 may be on to something! Thanks for suggestions.

 

[wolfehunter]

Just rechecked codes P2195 and P2197 and they are both sensor # 1's. Both on top side of engine so won't have to crawl under!

 

[wolfehunter]

Wiring all intact on sensors. Possible the blocked air filter caused them to go bad? They are original O2 sensors and car has 130K so ordered two Motorcraft replacements. May as well put them in since nothing else turning up. We'll see

 

[wolfehunter]

I replaced both Bank 1 and Bank 2 Sensor #1's last evening with no change in the rough idle and bucking when in drive and stopped with foot on the brake. Did some research and a bad Mass Air Flow sensor and PCV valve can possibly cause these symptoms. Going to replace the MAF sensor first and then if still no improvement will try the PCV valve.

Will a bad catalytic converter cause these symptoms? I am thinking the O2 sensors AFTER the converter would have thrown the codes if that was the problem correct?

Other thing I guess it could be would be a bad fuel injector but wouldn't I have other symptoms under load if that was the cause?

What might I be overlooking that would maybe be an "easy fix"?

Thanks,
Scott

 

[mk378]

The codes are for "stuck lean" which really suggests an air leak, which is certainly likely after having rats under the hood.

Cylinder drop test to see if the misfiring is one cylinder or distributed among all of them.

Or like you said the MAF could be reading wrong.

A bad converter (doesn't convert) won't cause running problems but throws the converter not working code P0420. A bad converter (melted / clogged up) is more apparent driving than idling.

 

[Falkirk88]

A quick check for the MAF is to disconnect the MAF, start the engine and see how it runs. If it runs good, then the MAF is bad. If it still runs poorly, need to check for vacuum leaks.

 

[wolfehunter]

I did unplug it while the car was running and it stalled but didn't unplug before starting it. Does it make a difference?

Sprayed carb cleaner around all vacuum lines with no change in rpm but maybe didn't hit the leak. No hissing or high pitch noise either. I may replace the intake gaskets next just to be sure.

 

[Falkirk88]

Yes, you want to disconnect the MAF before starting. This should make the ECM use a fixed set of parameters to allow the engine to run. That is, if this year allows it.


Another thing to check is the EVAP solenoid. If this is leaking(stuck open), this will cause a lean condition at idle. These are a common failure item on Fords.

 

[Number_35]

That's the Duratec 3.0, correct? With my friend's '06 Mazda MPV, there was a complex air hose that ran to the rear bank. It may have been hooked up to the power brake booster. Anyway, it had weakened and collapsed at around 200K km (120K miles) and had created a bad vacuum leak. Symptoms were very much as you've described. Not hard to replace. Sorry I don't remember the exact details - that was a few years ago now.

 

[wolfehunter]

Thanks for the tips. MAF sensor coming tomorrow but will disconnect and test per instructions. Will research the EVAP solenoid and check out that vacuum line. Keep you posted.

 

[wolfehunter]

Started car with MAF unplugged with no change to idle. It is a 6 wire MAF sensor so I checked it with a multimeter and it seems to be sending signal to the PCM correctly as voltage increased with rpm's. I cancelled the new MAF sensor order. I pulled the EGR valve last night and have it soaking in solvent to try and clean it up. I don't have a vacuum pump to test it. Probably should just replace it as I'd hate to put it all back together and the cleaned up EGR be the culprit.

And the vacuum line running from the EGR valve to the exhaust manifold is metal so not leaking. Did not find any other vacuum lines that looked bad or running to any of the banks. Will recheck though before putting it all back together.

 

[clinebarger]

Fuel Trim values are the best diagnostic tool/parameter for this concern

*Monitor the long term fuel trims, if fuel trims are high (over 10%) at idle only, but come down off idle, suspect a vacuum leak. Use short term fuel trims while spraying carburetor spray around all intake areas, if fuel trims drop into negative numbers in any particular area, suspect that area as a leak. On this particular vehicle, pay special attention when spraying around the upper intake gaskets, and inspect closely at the PCV tube for cracks or collapsed PCV hose.

*If fuel trims are fine at idle, but are excessively high during acceleration or cruising speeds, suspect fuel concern, or mass air flow input concern.

*Check fuel pressure during the concern, if fuel pressure drops below 30 PSI during low power concern. Check power and ground to the fuel pump during the concern. If no power or ground is lost during low fuel pressure, suspect plugged fuel filter or weak pump.

*If the fuel pressure does not drop during a lack of power or high fuel trim event, first check the mass air flow voltage. In most cases, normal voltage will be .6 to .9 volts at idle. Compare mass air flow voltages to specification. In most cases, if the mass air flow is the cause of the lean condition, unplugging the mass air flow sensor and road testing can be an effective means of diagnosing. If concern is still present with the mass air flow sensor unplugged, it is unlikely the mass air flow sensor is the cause.

*If fuel pressure, mass air flow voltage is ok, and there are no vacuum leaks, suspect fuel quality concern or possible plugged injectors.

 

[wolfehunter]

Thank you for the advice on the fuel trim numbers. I don't have the equipment to do that.

Tried a new Manifold Intake Pressure switch and did not resolve the issue. Ruled out EGR valve as it is working properly. Replaced upper intake manifold gaskets while I had it apart as a known problem area. Still persisits.

I payed closer attention to the idle behavior upon trying these different sensors and hoping I solved it. I notice that upon first starting the car the idle is high as it is warming up the engine and it idles terrific leading me to sometimes think......."maybe I solved the issue"........big let down each time!! As the car warms and the idle starts slowly falling it begins to gallop somewhere around 800 rpm's. It does this for maybe 15-20 seconds and the fast idle picks up again pushing it up to about 1200 rpm's for awhile and I keep thinking maybe the computer is doing the idle relearn sequence and it will correct itself. Nope........as the idle eventually starts to come down below 1000 rpm's to around 800 it begins to gallop again. A few times it has stalled after the second fast idle phase and it drops rpm's.

I again looked for vacuum leaks, bad hoses or pinholes and sprayed everything with carb/choke cleaner with no changes to the idle. But kind of hard to recognize a change when it sits there constantly fluctuating from 700 to 800 to 700 rpm's continuously.

I am going to test voltage at all 6 ignition coils and fuel injectors next. I give up on vacuum related issues. I refuse to give up.

 

[wolfehunter]

Fuel Injector Resistance: Cylinder #1 12.5 ohms, Cylinder #2 12.5 ohms, Cylinder #3 12.7 ohms, Cylinder #4 12.5 ohms, Cylinder #5 12.5 ohms, Cylinder #6 11.1 ohms. Acceptable range is 11-18 ohms so although #6 is lower I don't think that is the problem.

Ignition Coil Resistance: Cylinder #1 B+ to tach 1.2 ohms and B+ to spark plug end 13.75k ohms, #2 1.2 ohms and 10.62k ohms, #3 1.1 ohms and 11.66k ohms, #4 1.1 ohms and 12.31k ohms, #5 1.2 ohms and 14.7k ohms, #6 1.2 ohms and 12.91k ohms.

All the coils are between10.62k ohms and 14.7k ohms which I'm thinking is acceptable but I couldn't find any definite specs on them. Anyone see anything out of whack? I tested them all with the engine stone cold. Wondered about letting engine warm and retest everything to see if any variance. I would have to put the intake back on, warm the car and then hastily take the intake manifold while engine still warm to get at the injectors and #1,2 and 3 ignition coils. GGGGGRRRRRRRRR!

Noticed the car does have an exhaust leak that I don't think I noticed before. Related to my problem in any way? Soon time to take it to someone that can run the fuel trim data. I did put forth my best effort.

 

[gathermewool]

Fuel trim is irrelevant until you drive the car some. They're not called long-term fuel trims for nothing'.

Have you driven the car to see whether the codes come back?

What about an idle relearn?