1997 4.6L issues HELP with ideas please

[joshNphoenix]

I’ve had my truck for over 10 years and have never had an issue. But in the last month has been running rough. To the point of almost stalling and shudders sometimes. Also noticed a whistle noise that’s new. Scanned it and they said EGR Valve bought a new one and changed it. Same issue no change just out 50 bucks. Just pulled codes tonight and they are
P0301 cyl 1 misfire
P0155 02 heat circuit bank 1 sensor 1
P0135 02 heat circuit bank 1 sensor 2
P0303 cyl 3 misfire
P0171 bank 1 too lean
P0174 bank 2 too lean
Just wondering if anyone has had this issue and what was the issue. Thanks in advance for any advice at this point. Josh

 

[Killer Ride]

Do you have Cataytic converters ?
If they havent been checked in a while I would take it to an exhaust shop and have them do a back pressure test. They could be clogged.

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[riphip]

Codes points to possible vacuum leaks and possible low fuel pressure. After 23 years, I would check/replace old vacuum hoses, PCV and check all rubber elbows (cheapest route/repair). Could be that simple.
https://www.rockauto.com/en/catalog/ford,1997,expedition,4.6l+v8,1119574,exhaust+&+emission

 

[Trainmaster]

Like rip says, you may have a vacuum leak. Check those EGR hoses.

 

[docraymund]

Check or replace spark plugs on cylinder 1 and 3, check fuel pressure at idle and while revving, if low, change fuel filter, if still low, change fuel pump. If still running rough after verifying spark plugs 1 and 3, and fuel pressure is normal, try bending the tabs of the fuel injector male connector a little (carefully) to ensure good contact. If that doesn't work, and misfire is still on 1 and 3, either try replacing the fuel injector or check the fuel injector female lead with a noid light.

 

[mnachreiner86]

IAC on the whistle?


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[Bruce Mitchell]

Start small and work your way up. Fuel filter and vacuum lines. Occam's Razor almost always applies.

 

[mrphixit]

I’ve had my truck for over 10 years and have never had an issue. But in the last month has been running rough. To the point of almost stalling and shudders sometimes. Also noticed a whistle noise that’s new. Scanned it and they said EGR Valve bought a new one and changed it. Same issue no change just out 50 bucks. Just pulled codes tonight and they are
P0301 cyl 1 misfire
P0155 02 heat circuit bank 1 sensor 1
P0135 02 heat circuit bank 1 sensor 2
P0303 cyl 3 misfire
P0171 bank 1 too lean
P0174 bank 2 too lean
Just wondering if anyone has had this issue and what was the issue. Thanks in advance for any advice at this point. Josh

 

[mrphixit]

I had the same symptoms that you’re describing with my 99 5.4. I’m not sure if the 4.6 has it or not but my 5.4 has a vacuum line from the PC valve to the rear of the intake. The rubber coupling connecting it to the intake deteriorates and the engine runs horrible if it even runs at all. It is a real bear to replace unless you pull the throttle body. If I remember correctly, that hose is actually 2 or 3 Hoses connected with a Y or Tee and cost about $60 ten years ago. Hope this helps.

 

[00XTL]

The heater circuit codes might just be bad o2 sensors. Although it strange that they both went out at the same time. But they are cheap and easy fix. The misfire codes and lean codes sound like a vacuum leak. Intake gaskets could be leaking as well. I have an 00 5.4 that only ran like crap at stop lights. Installed new intake gaskets and haven’t had a problem since. It’s about to hit 400k

 

[Tan Exp]

yea do plugs and check your main battery.

 

[Tan Exp]

yea do plugs and check your main battery.

 

[KingRatt]

Bad head gasket also in the mix.

 

[danimerciss22]

Do you have Cataytic converters ?

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[k4vbb]

There are "typically" 2 reasons for an engine to run lean. One is a vacuum leak. This means that un-metered air (air that the MAF can not account for) is entering the system somewhere. This could be as simple as a disconnected or broken vacuum line. Be aware that vacuum lines in the cab can also affect air metering. A leak in the intake manifold mating surface can also be a cause, but I would venture to say that this is a bit more rare. A smoke test is the best way, but sometimes you can find them by spraying around the engine compartment with some starting fluid.

Another cause is clogged catalytic converters. When the exhaust gas can't escape, the engine can't let in enough air. The computer will then reduce the amount of fuel to match that of the incoming air stream, which will not be sufficient to produce the required engine power.

BUT! If you're having problems with the front 2 O2 sensor readings, the only way you can be sure that their output can be trusted (by you AND the engine computer) is by swapping in known-good sensors. That in itself "may" solve your problem. If you're lucky.