Ford V10 Techs - Both Banks Lean

[u118224]

A friend has a 1999 E350 V10 and it's throwing p0171 and P0174. We've checked for leaks, sprayed carb cleaner around the intake but haven't found anything. I don't have a smoke machine, which would make things considerably easier. I checked and cleaned the MAF but it really wasn't dirty. I think the truck has less than 100,000 miles. Any thoughts?

 

[WhiffySpark]

Check fuel pressure regulator

 

[jonzer12]

Check fuel pressure?

 

[u118224]

I checked fuel pressure last year and it was within spec. I cleared the code and he drove it the rest of last summer. The truck was parked for the winter and he recently put it back on the road. The codes set when he was idling the truck for an extended period. I'll check fuel pressure again.

 

[Super Mech]

Check for a vacuum leak in the PVC sytem(elbows, hoses,etc.). Very possible it could be plenum gaskets also, but w/o a smoke machine it's hard to tell. Sometimes it's the MAF sensor but I've seen PCV hoses to be the most common cause.

 

[WhiffySpark]

I checked fuel pressure last year and it was within spec. I cleared the code and he drove it the rest of last summer. The truck was parked for the winter and he recently put it back on the road. The codes set when he was idling the truck for an extended period. I'll check fuel pressure again.

Not fuel pressure. You need to test the regulator. Ford is known for it.

Those plastic manifolds always seem to be a damn problem too if it's an earlier v10. Check your o2 sensor readings as well

 

[WhiffySpark]

Also, you can check for leak with a vacuum gauge. If it doesn't read right smoke machine would be next step

 

[MLB0611]

Lots of bad info, use a scan tool that shows fuel trim short and long term at idle is the short term pegged at 25% and if you rev it up do the trims go close to 0 on short term? if so you have a vacuum leak if it is around 0 at idle watch front 0 2 sensors snap the throttle, does it go to 900 mV, then do a hard run with it if they still go to 900 mV then it is not fuel related it would be likely a MAF problem.

 

[u118224]

Thanks, I checked fuel trim last fall but I felt it was inconclusive. I'll check again and report back. Thanks to all who have responded.

 

[theoldwizard1]

PVC and power brake hose and fittings as well as all other vacuum connections.

At that age, the PVC grommet(s) and hoses get soft and leak.

 

[WhiffySpark]

I have never replaced a PVC hose for a lean code in 10 years. Or any vacuum connections or fittings.

 

[Super Mech]

I have never replaced a PVC hose for a lean code in 10 years. Or any vacuum connections or fittings.

Then you don't work on many Fords.

 

[WhiffySpark]

Then you don't work on many Fords.

Yup all day long. Had 3 fleets of Eco line vans.

I hated my life then. Lol

 

[Dr.phil]

plugged fuel filter

 

[MLB0611]

Yup all day long. Had 3 fleets of Eco line vans.

I hated my life then. Lol

Were they all diesels? because I have replace hundreds of Vacuum harnesses on fords from the common PCV elbow on 5.4s to the 3.0 main Vacuum harness etc all for lean codes

 

[ryanl925]

I have never replaced a PVC hose for a lean code in 10 years. Or any vacuum connections or fittings.

I guess you don't work on ford trucks much.

 

[jethro29]

to check for an intake leak on these engines you HAVE to check when the engine is STONE COLD like after it sits all night.99% of the time an intake leak on these motors will NOT SHOW UP WHEN THE MOTOR IS WARM.also check fuel pressure and volume.any exhaust leaks?

 

[jethro29]

i have never replaced a pvc hose for a lean code in 10 years. Or any vacuum connections or fittings.

lol.

 

[KineticDissent]

Any freeze frame data available?

 

[u118224]

Any freeze frame data available?

I hope to get my scanner on it tomorrow or Monday. I'll report back.

 

[u118224]

to check for an intake leak on these engines you HAVE to check when the engine is STONE COLD like after it sits all night.99% of the time an intake leak on these motors will NOT SHOW UP WHEN THE MOTOR IS WARM.also check fuel pressure and volume.any exhaust leaks?

There's no exhaust leaks. I can't read fuel trims on a cold motor, at least not until the O2 sensors are warmed up. I can check fuel pressure, checking volume is a PIA. I really don't think it's a fuel problem but I'll know for sure once I can read the short term trims.

 

[cludwin]

So I haven't worked on a V10 before but when you get both banks lean that means 1 of two things you're not getting enough fuel or air is getting in past the mass air sensor which isn't being accounted for. If you have already replaced the fuel filter then the I would suspect it's running lean due to air getting in past the MAF sensor because it's both banks. You'd have to be really unlucky to have a fuel delivery problem that just happens to live on both sides of your motor if it wasn't the fuel filter.

I had the same problem on my ranger and it ended up being the upper intake gasket was leaking. I tried spraying ether all over the motor looking for a surge in RPM's but the leak was slow enough so that I never heard the RPM's serge when I sprayed. In the end I tested the pressure at the fuel rail and it was good so I guessed it had to be a leaking intake gasket.

I replaced the gaskets about 2 years ago and I haven't had a lean code since.

Good luck this one drove me crazy.

 

[JTH]

My memory is BARO PID would be off if MAF has an issue. It's been a few years and I can't recall numbers but it would make both banks fuel trim off. On motor homes it was usually oiled K&N filter or water soaked air filter.