Another thing....I haven't driven her with the doghouse on since I first started working on her...makes me wonder if the 'house was just hiding the pinging???

 

You might have an injector leaking, and the excess fuel is making it hydrolock - be careful.

It's the only way you'd get fuel in there with the injectors disconnected. But it's usually just one injector...

 

So. During last drive. If i punch it to pull out on highway, it sounds like she's backfiring, but it sounds like its under the rig. Like a boat exhaust. I've always attributed that to WAY retarded timing. Once she catches, she hauls. The REAL pinging is around 3k RPM, then she shifts, and the pinging is still there, but less. If I REALLY hammer it (drop two gears), 90% of the pinging goes away. The 'house DEFINITELY hides most of the pinging. Definatly didn't ping on MY first trip with her.

My scanner actually has a troubleshooting section, and spark knock is one of the areas (it changes troubleshooting advice based on what vehicle I tell it it's connected to!!!).

Verify FP is in spec.
Maf and BARO for correct reading.
Excessive EGR flow.
Monitor short fuel trim and spark advance while driving. If SFT goes up and SA retards, check for correct PCV valve.
PCV valve fluttering at idle.

 

Krewat,
I'm starting to wonder about my fuel delivery. My Haynes manual states:
"Fuel Pressure; 6.8L V10; 2006 and earlier; KOEO 35-45psi; KEOR 28-45psi".
According to my scanner, FRP_DSD (fuel rail pressure desired) is calling for 65psi (almost 50% over what my book says should be) on both engine off and running. Live data KEOR reflects that. Fuel rails pressure sensor shows KOER FRP at 64-65psi. With 20# of pressure over what should be there, that would explain the rich exhaust.

KOEO, fuel pressure starts at 44psi, and drops to 38 within 5 minutes. My book states "Fuel system hold pressure (after 5 minutes) 30-40psi. My 5-minute test is within specs, but with what you said about a leaky injector and watching the pressure drop, leads me to leaky injector(s). Especially since all 10 plugs obviously had excess fuel when pulled for the compression test.

Since all the injectors have the same mileage on them (219k), if ONE is leaking, the others aren't far behind.

What would be making the computer ask for 65psi at idle, or ANY time really..? Could that be a sign of a faulty FPS?

 

Bump?

Anyone got any ideas on the high fuel pressure (both desired AND delivered, at idle or at speed)? I have a mechanical fuel pressure gauge coming tomorrow to verify that is what's truely hitting the injectors. If it is, where should I look next?

Mc

 

I can't lend much to this at this point, because I think the newer fuel injection systems are different in terms of fuel pressure regulator, what the computer calls for (and how), etc. (I'm not sure if it really changes, just saying I have no experience with the newer systems).

But - if the computer is calling for 65PSI at idle or when the engine is off, that sounds like a LOT - the specs from your Haynes manual are more what I expect on the earlier systems - 28-30 at idle, 38-40 under load. KOEO, 38-40 PSI. On the older systems, they use a vacuum-regulated FPS - at high engine vacuum (idle), pressure is 28-30, low engine vacuum (under load or engine not running but key on) 38-40.

I'd be leary of what the scanner is telling you too - never take what it says as gospel. A PID in the PCM could be saying it's "calling for" 65PSI - but it's really an unused PID.

Do you have an FPR that's visible, and does it have a vacuum line going to it?

 

Yes to the FPR, and yes, it has a vacuum line. I got an inline fuel pressure tester setup at NAPA ($150...glad I got it). This is probably the ONE thing they put in an easy spot. Top of engine. Farthest back. I feel for you truck guys if it's in the same place on the '06 v10. Then again, you can SEE your spark plugs.

I cycled key, bled fuel from gauge, repeated until I had solid fuel in release hose. No air in the setup. Should be the best fuel pressure reading I can get.

KOEO:
Spike to 90 for 1 sec then drops to 58 and holds. When I shut off key it drops to ~45 within 1 second. Every time I turn the key to run, this happens.

KOER:
While cranking, varies between 50-70 until she starts. 54-56 while idle. Same when RPM brought up to 2k. Remove vacuum line. Goes up to 68, idle or 2k.

Shut engine off and it goes to 45. 45 minutes later, it's at 42. I'm saying my injectors are good, they just can't hold back 60psi of fuel pressure. With the pump off, the injectors bleed fuel until it gets to the 40's. Same while running. They are designed to allow a metered amount of fuel by each time they open. With 50% more pressure, 50% more fuel enters the cylinder? 02 sensors see this and try to (advance?) the timing, but can't go far enough, making it ping (pre-ignition)?

This thing has a Fuel Pump Drive Module. I understand it to be like a VFD for a well pump. More demand (pressure drops), computer tells pump to spin faster, making more pressure. I'm thinking the fuel pressure sensor is bad.

Getting a vacuum gauge tomorrow to make sure the engine is pulling what it should be. Also trying to find pin-outs and testing steps for this sensor. I did order a new FPS, PCV valve, and FPDM. I'm still going to see if I can find how to test the FPS, but those are the three parts I'm leaning to.

If the pump peaks to 90 and can hold almost 70, I'm ruling out pump-related issues.

Removed FPDM. No cracks, no serious corrosion. Reinstalled.

McMechanic

 

Replaced FPR, PCV, AND FPDM. Still have 65psi no matter what. I can't find anything else as for where to go next. I dont have much hair left.

 

The only thing left is the PCM is telling the FPDM to keep the pressure up high at all times. Usually, the PCM will drive an external output by dragging it to ground, and pulse-width modulating it to vary the speed or pressure. If the output in the PCM is shorted to ground, it will drive the FPDM at 100%. However, in situations like this, the PCM usually has a test for this and a way of sensing if the PCM is driving the circuit at 100% and throw a DTC.

See if you can check the voltage at the FPDM input, if there is such a thing. I'm just theorizing, I have no idea how the return-less fuel system works (I'm assuming it's return-less) ? If you had a 'scope, that would be even better.

 

I don't have an oscilliscope, just my Solus Pro. And a DVM. About all i can do at this point is replace the PCM (cant find wiring diagrams/pinouts/voltages). If i had that info, i might be able to dig a little deeper. Bad part about the PCM, it has to be flasjed in the vehicle...which would mean getting it on a trailer and towing it 2 hours to the nearest dealership.

 

Yes, its returnless. The way i understand it, the fuel,pressure sensor talks to the PCM, which talks to,the fuel pump driver, which talks to the fule pump. Tge system just sppeds up or slows down the fuel pump to maintain desired pressure.

 

The kicker is the OGHER bus i have to work on is an '05 with 6.0 diesel and a no start....an no manual...

 

Um, do you have a scanner that can read PID's? What does the PCM THINK the pressure is?

 

My Solus can read PIDs. According to my scanner, the DESIRED fuel pressure is 65, and the ACTUAL fuel pressure is 65. By mymechanical gauge, it sits at 58-59psi.

 

Hmmm... so for some reason the PCM WANTS 65 psi.

Interesting read:

Under Pressure: Maintaining Ford?s Electronic Returnless Fuel System

If the fuel temp is high, the PCM wants to keep the pressure high to prevent vaporization.

can you check for a fuel temp PID and see what it says?