Figured I would tap the expert minds here:

2006 Ford F-150 4.6L 4WD - 112,000 miles

Issue: Idles rough once truck reaches normal operating temperature and then has some stumbling on acceleration.

Truck was running fine when it was parked to rebuild rear end. Sat for about 6-7 weeks with about 1/4 tank of gas.

Parts installed chasing down this issue (all were done within last 2 weeks except plugs):
Plugs (last Summer - about 5,000 miles on them)
COP’s
Throttle position sensor
Throttle body gasket (smoke test showed leak)
Fuel pump delivery module
Both upstream O2 sensors
Air filter
MAF inspected and cleaned with MAF cleaner

I have use of a family member’s Matco Maximus 2.0 diagnostic tablet. These are the only off the wall readings I got:

Absolute throttle position B, D and F are in the red, but regular absolute position is fine
Short term fuel trim B1S2 and B2S2 are 99.2 and do not change at all

No injector faults
Power balance test is good
All other sensors show within range

I am leaning towards EGR and here is why: When I unplugged the dual vacuum line and tried to pull a vacuum on the 2 ports, this is what happened.
Bottom port - pulled and held a steady vacuum.
Top ports - I was unable to pull a vacuum. As I squeezed trigger to apply vacuum, needle would barely move and stay around zero.

Any ideas?

This message has been edited. Last edited by: RBeach,

What brand COP’s did you use? The Chinesium’s are hit or miss if you didn’t go with Ford COP’s. Was the original TPS bad?

Vacum hose at rear of throttle body.

quote:

Originally posted by PowerSurge:
What brand COP’s did you use? The Chinesium’s are hit or miss if you didn’t go with Ford COP’s. Was the original TPS bad?

This^^. Also what brand O2 sensors? I would definitely run OEM sensors as well.

Disregard the short term readings from the B1S2 and B2S2, as these are the post cat o2's and are only used for cat efficiency.

Should be looking at the short term and long term fuel trims for the B1S1 and B2S1 sensors. This will give you a read on how the engine is running, lean or rich.

If running lean, check for vacuum leaks and check fuel pressure. Just because you replaced the fuel pump, it doesn't mean it is good. This is another place where I would use OEM.

quote:

Originally posted by PowerSurge:
What brand COP’s did you use? The Chinesium’s are hit or miss if you didn’t go with Ford COP’s. Was the original TPS bad?

I got them from Amazon. ENA Premium brand. Got them because of the reviews. 4.5 stars out of 1,934 reviews. Granted, I know everyone pushes factory, but I have used these before on previous vehicles with. No issues. Plus. I am not getting any misfire codes. I even unbolted and pulled them off one by one.

quote:

Originally posted by 21bubba:
Vacum hose at rear of throttle body.

It is good. No breaks or leaks. That was one of the first places I checked after I found the video that said that 90 degree elbow is prone to breakage.

quote:

Originally posted by Shifferbrains:

quote:

Originally posted by PowerSurge:
What brand COP’s did you use? The Chinesium’s are hit or miss if you didn’t go with Ford COP’s. Was the original TPS bad?

This^^. Also what brand O2 sensors? I would definitely run OEM sensors as well.

Disregard the short term readings from the B1S2 and B2S2, as these are the post cat o2's and are only used for cat efficiency.

Should be looking at the short term and long term fuel trims for the B1S1 and B2S1 sensors. This will give you a read on how the engine is running, lean or rich.

If running lean, check for vacuum leaks and check fuel pressure. Just because you replaced the fuel pump, it doesn't mean it is good. This is another place where I would use OEM.

O2 sensors are Bosch.

Pressure at fuel tank is 39.79 PSI
Pressure at fuel rail is 39.69 PSI

quote:

Originally posted by RBeach:

quote:

Originally posted by PowerSurge:
What brand COP’s did you use? The Chinesium’s are hit or miss if you didn’t go with Ford COP’s. Was the original TPS bad?

I got them from Amazon. ENA Premium brand. Got them because of the reviews. 4.5 stars out of 1,934 reviews. Granted, I know everyone pushes factory, but I have used these before on previous vehicles with. No issues. Plus. I am not getting any misfire codes. I even unbolted and pulled them off one by one.

Unless the OEM Ford ones were bad, I would re-install them. On those Ford modular engines a lot of times you won’t get a misfire code with a bad COP. If one of the Chinesium COP’s (or even a Ford COP) is bad they will act fine until they get heated up from the engine and then act up.

quote:

Should be looking at the short term and long term fuel trims for the B1S1 and B2S1 sensors. This will give you a read on how the engine is running, lean or rich

At idle:

STFT B1S1 = .78 (-15-15 standard)
STFT B2S1 = -2.34 (-15-15 standard)

quote:

Originally posted by PowerSurge:

quote:

Originally posted by RBeach:

quote:

Originally posted by PowerSurge:
What brand COP’s did you use? The Chinesium’s are hit or miss if you didn’t go with Ford COP’s. Was the original TPS bad?

I got them from Amazon. ENA Premium brand. Got them because of the reviews. 4.5 stars out of 1,934 reviews. Granted, I know everyone pushes factory, but I have used these before on previous vehicles with. No issues. Plus. I am not getting any misfire codes. I even unbolted and pulled them off one by one.

Unless, the OEM Ford ones were bad, I would re-install them. On those Ford modular engines a lot of times you won’t get a misfire code with a bad COP. If one of the Chinesium COP’s (or even a Ford COP) is bad they will act fine until they get heated up from the engine and then act up.

I should state the issue was there before COP’s were replaced. I did it as preventative.

Ok. Then I would check EGR and IAC valve.

quote:

Originally posted by PowerSurge:
Ok. Then I would check EGR and IAC valve.

It is electronic throttle, so no IAC.

I think EGR valve next as well. $110 for the Motorcraft one. Just odd that the top port was not holding a vacuum but bottom one was.

Just hate throwing parts at it, but I am lost at this point.

I miss my 69 Mustang and the 1980 Datsun pickup. Yes, the Datsun. Both were so dang easy to work on, if they ever needed it.

I replaced the alternator on my daughter’s 92 Honda Civic tonight and took me maybe 30 minutes. Why can’t they make them that easy anymore? You need to computers to fix the computers in them.

Yeah, I was thinking of the 4.2 V6. It has an IAC. The more I think about it the more it makes sense about the EGR since the truck sat for almost two months.

While you’re at it do a visual on all the vacuum lines. Looks like you already did a smoke test so may not be necessary now.

Since you have the Maximus, graph the MAF, both upstream O2's, and if you can both ST Fuel trims. Drive the truck, and from a stop take off smoothly to WOT and watch the graphs. The MAF, O2's and fuel trims should go high, pretty much mirror each other.

There is a possibility that the MAF is bad. Just because it looks ok and is clean, doesn't mean it is good. Now I don't know if 2006 Fords have a generic MAF algorithm when the MAF is disconnected. You can check this by disconnecting the MAF and start the engine. If the engine runs, then it does have a generic algorithm. Go drive the truck and see if the rough idle and stumbling are gone. If it is, then the MAF is the issue.

^^^This. I went back and reread the op. I mistakenly thought the MAF was also replaced with the other parts, but it says it was inspected and cleaned.

As far as the EGR goes, you are thinking that it is partially open. Disconnect the vacuum lines and while the engine is idling feel the base of the EGR valve just under the diaphragm. If it gets and stays hot to the touch, then it probably is leaking. If it stays relatively cool, then exhaust gas is not flowing.

Also check for vacuum on the lines while idling, there should not be any vacuum. If there is vacuum, this may have an EGR control valve that has a plugged vent filter. This usually resides on the firewall, and has a cover that can be removed to remove the filter. This is a quick fast way that we can check to see if the EGR valve works, pull the cover, filter and place finger over the vent opening. If the engine stumbles, then the valve is working.

quote:

Originally posted by Shifferbrains:
Since you have the Maximus, graph the MAF, both upstream O2's, and if you can both ST Fuel trims. Drive the truck, and from a stop take off smoothly to WOT and watch the graphs. The MAF, O2's and fuel trims should go high, pretty much mirror each other.

There is a possibility that the MAF is bad. Just because it looks ok and is clean, doesn't mean it is good. Now I don't know if 2006 Fords have a generic MAF algorithm when the MAF is disconnected. You can check this by disconnecting the MAF and start the engine. If the engine runs, then it does have a generic algorithm. Go drive the truck and see if the rough idle and stumbling are gone. If it is, then the MAF is the issue.

Ford's will run with the MAF disconnected, but usually not very well. Usually cleaning them would lead to screwing them up on Fords. I would guess this is the culprit.

quote:

Originally posted by jimmy123x:

quote:

Originally posted by Shifferbrains:
Since you have the Maximus, graph the MAF, both upstream O2's, and if you can both ST Fuel trims. Drive the truck, and from a stop take off smoothly to WOT and watch the graphs. The MAF, O2's and fuel trims should go high, pretty much mirror each other.

There is a possibility that the MAF is bad. Just because it looks ok and is clean, doesn't mean it is good. Now I don't know if 2006 Fords have a generic MAF algorithm when the MAF is disconnected. You can check this by disconnecting the MAF and start the engine. If the engine runs, then it does have a generic algorithm. Go drive the truck and see if the rough idle and stumbling are gone. If it is, then the MAF is the issue.

Ford's will run with the MAF disconnected, but usually not very well. Usually cleaning them would lead to screwing them up on Fords. I would guess this is the culprit.

If it runs, it has a generic algorithm and runs on a fixed set of parameters, and will run well enough to determine if the MAF is bad. I clean the MAF sensors on Fords all of the time, I have never damaged one by doing so. You will damage a Ford MAF if you are ham fisted cleaning the sensing resistor or do not let the sensing wire fully dry before starting the engine.

RBeach,

Make sure that the snorkel from the air cleaner to the intake is properly seated and tight, and there are no splits that can allow unmetered air into the engine.

quote:

Originally posted by Shifferbrains:
Since you have the Maximus, graph the MAF, both upstream O2's, and if you can both ST Fuel trims. Drive the truck, and from a stop take off smoothly to WOT and watch the graphs. The MAF, O2's and fuel trims should go high, pretty much mirror each other.

There is a possibility that the MAF is bad. Just because it looks ok and is clean, doesn't mean it is good. Now I don't know if 2006 Fords have a generic MAF algorithm when the MAF is disconnected. You can check this by disconnecting the MAF and start the engine. If the engine runs, then it does have a generic algorithm. Go drive the truck and see if the rough idle and stumbling are gone. If it is, then the MAF is the issue.

I will do this tomorrow when I get home from work. I haven’t done the graphing with it yet. This thing has so many freaking features, I now see why he paid so much for it.

I was trying to watch live data as I drove it, and the MAF seemed to stay in range. I will check again tomorrow to be sure.