Fuel pressure is 36 idle and 40 psi with throttle. When I turned off the engine and let it sit for 5 minutes, the pressure gauge was 5 psi lower than when the engine was running.

 

Have you checked if there’s an inline fuel filter and if so, have you replaced it? It would be along the inside of the driver side frame rail if it’s there.

 

Yes I put A new Motorcraft fuel filter on it back in June along with new Motorcraft air filter. I'm thinking about ordering noid light to see if the injector pulse is ok. If I recall correctly, pulsing light on noid means everything is ok, no light means no current, solid light somethings wrong or bad pulse from ECU. I pulled all coils one by one and verified there is spark on all of them with spark tester. I am not sure if this will tell you anything, but it doesn't run too bad when start up cold after sitting overnight, still A little rough idle. When I drive it lets say 10 miles, park it at Subway shut it off long enough to eat lunch. It runs a lot rougher at warm start up to the point of shaking the whole truck. Clears up when driving about 1500 rpm and higher. rough idle is back at stop light though.

 

I have a couple other suggestions for you, otherwise I’m at a standstill until you check the vacuum (you might say I’m stuck at idle ).

1) Perform a hard reset - disconnect both battery cables and clamp or bolt them together for 1/2 an hour to completely clear the PCM memory (this will not affect security protocols or create a no start condition). Afterwards, drive it for at least 20 miles with as much time on the highway at cruising speed as possible. Engine and transmission performance may be rough at first but that’s only because the PCM has to relearn adaptive values.

2) Fuel pump volume test - pressure is good but volume may not be. Relieve fuel pressure and disconnect the fuel line either at the rail or at the filter (post filter if you go there). Attach a length of hose to the line (3/8” should work) and make sure it’s directed into a container - paint mixing cups work well for this as they’re marked for volume and can tolerate gas exposure.

Jump pins 30 and 87 of the fuel pump relay (key doesn’t have to be on - pin 30 is hot at all times) and run the pump for either 5 seconds, 10 seconds or until the container is full (if the container fills up between 5 and 10 seconds, keep track of how long - a stop watch is recommended). Once you know the volume collected, multiply it by the appropriate factor depending on how long the pump runs.

You want to see a minimum of 1 pint in 30 seconds; so if running for 5 seconds, multiply by 6; if 10 seconds, multiply by 3, etc.

If the result is less than 1 pint, repeat the test pre-filter. I know it was recently replaced but an increase in volume pre-filter indicates it’s clogged. No increase indicates a weak pump.

 

[QUOTE=DBGrif91;19026095]I have a couple other suggestions for you, otherwise I’m at a standstill until you check the vacuum (you might say I’m stuck at idle ).

1) Perform a hard reset - disconnect both battery cables and clamp or bolt them together for 1/2 an hour to completely clear the PCM memory (this will not affect security protocols or create a no start condition). Afterwards, drive it for at least 20 miles with as much time on the highway at cruising speed as possible. Engine and transmission performance may be rough at first but that’s only because the PCM has to relearn adaptive values.

2) Fuel pump volume test - pressure is good but volume may not be. Relieve fuel pressure and disconnect the fuel line either at the rail or at the filter (post filter if you go there). Attach a length of hose to the line (3/8” should work) and make sure it’s directed into a container - paint mixing cups work well for this as they’re marked for volume and can tolerate gas exposure.

Jump pins 30 and 87 of the fuel pump relay (key doesn’t have to be on - pin 30 is hot at all times) and run the pump for either 5 seconds, 10 seconds or until the container is full (if the container fills up between 5 and 10 seconds, keep track of how long - a stop watch is recommended). Once you know the volume collected, multiply it by the appropriate factor depending on how long the pump runs.

You want to see a minimum of 1 pint in 30 seconds; so if running for 5 seconds, multiply by 6; if 10 seconds, multiply by 3, etc.

If the result is less than 1 pint, repeat the test pre-filter. I know it was recently replaced but an increase in volume pre-filter indicates it’s clogged. No increase indicates a weak pump.[/Q
My vacuum gauge finally came in today. The first pic is the reading at idle and normal operating temperature. The second is 2500 to 2700 rpm at normal operating temperature. I also did that fuel volume test and got 4 & 3/4 pints of gasoline in A jug in 30 seconds.

 

Well....

The vacuum readings look normal as long as they were stable and didn’t drop off.

There’s a few other things that come to mind, but basically if nothing comes of this, I don’t know what else to suggest. This is indeed a head scratcher.

1) I’m not trying to beat a dead horse, but I think there needs to be confirmation of the intake manifold being properly sealed. The intakes on the triton 4.6 and 5.4 engines of this era are known to warp and split at the seams. I would think if this were the case you’d be seeing system lean codes but it’s possible the leak(s) may not be bad enough. Get it smoke tested - if there’s any leaks at all, the smoke test will confirm it.

2) Did you try the hard reset on the PCM?

3) What’s the quality of gas you normally run (top tier or cheapest you can find) and when’s the last time you put fuel system cleaner through it (sea foam, marvel mystery oil, etc)?

4) Unplug the MAF sensor and inspect the female side (harness) of the connector - you may have to remove the retaining clip for a good view, but you’re looking for the terminals to appear spread out. Loose connections at the MAF can affect idle. If that checks out, tap lightly on the MAF with a wood dowel or the handle of a screwdriver and see if idle gets worse - if so the MAF has a problem.

5) You can also try unplugging the MAF with the engine running - the engine should die or severely stumble before recovering - if there’s no change at all, either the MAF is faulty or the PCM isn’t receiving the signal.

 

I'm not sure what you mean by not dropping off...The vacuum gauge needle stayed steady both idle and revving motor to 2600 rpm and didn't fluctuate back and forth. Now when I snapped the throttle from idle to wide open throttle, the gauge dropped and instantly went back up to 50 like pics showed. And when letting off the throttle the gauge went to 60 and stabilized back to 50 once engine went to idle. I could do A video if this site allowed videos.
I will order A smoke machine. and update you with the results. Hopefully I'm not aggravating and bothering you.
Yes I've did the hard reset for 20 minutes with the pos. and neg. posts disconnected from the battery, and crossed together with jumper wire.
Tapping the MAF while engine was idle didn't make any difference. I had continuity on all wires from maf plug back to where I could probe it near the valve cover.
Engine stumbles very bad and eventually dies when MAF plug is disconnected.
So yeah even my local shop that has hi quality snap on scanners and tools are stumped. I'm getting tired of messing with it, however am persistent on getting the rough idle fixed.

 

You’re not bothering me at all, I’m just stumped at this point.

By dropping off, I mean the vacuum steadily decreases. With it holding steady at 2500 RPM there’s no reason to suspect restrictions in the intake or exhaust and as I said before, a momentary decrease with changes in engine RPM are normal.

If you really want to order a smoke machine, go for it, but maybe check with a shop to see what they’d charge to do it - could be less than the cost of buying one.

Is your truck flex fuel, or do you run any fuel with higher alcohol content such as E88 on a regular basis?

There is 1 TSB regarding rough idle and/or hard starting conditions, with or without codes - you might want to hit up your dealer and find out if the PCM is up to date with the calibrations (since it’s a replacement PCM it SHOULD have the latest software but the only way to know for sure is to check it - if your scan tool can read the PCM programming info you might be able to avoid the dealer)

TSB 12-7-4 Check the throttle plate position at operating temp at idle - it should be less than 3 degrees - if not, the PCM needs calibration.

 

Just reading on a Mustang forum where a guy had a broken chain guide. He replaced the timing set, and was positive he timed it right, but it ran just like yours. After trying to get it right, he finally went back in and re-marked the gears and chains, and he was one tooth off. Fixed it and it ran like new. May have to go back in.

 

But with his steady 20 inches of vacuum at idle, I think the timing is correct.
If the cam timing was off the vacuum would be low and bouncing.

 

He may be timed high. That vacuum looks too high for that engine to me, but I could be wrong.

 

Here in my area in West Virginia, 10% Ethanol is the max. I have ran cheap gas, mid grade, and Ethanol free high test with no change.
The shop wants $40 A hour for smoke test. I found A smoke machine on ebay for $60. I went ahead and ordered it and if I use it twice on my different vehicles, it'll pay for itself.
My scan tool isn't bidirectional, so I doubt it if it will tell me what software I have. I will try though.
Humm throttle plate angle makes sense due to low power at take off and power return at higher rpm's.

 

When I put the timing set and sprockets on, I noticed both cam sprockets turned say A half A tooth to the left and right. I didn't know where to put the sprockets to the proper place, so I could have possibly for example put bank 1 retard and bank 2 advance. I have looked online many times on how to set the cam sprockets on this 4.6 and I haven't found anything. I am not sure to put both cam sprockets to the left as far as they go and torque the bolts, or put them in the middle. I wish I would have just put the new chains and tensioners and left the old cam sprockets on there.
I dread it, but I will have to tear it apart again when the weather warms up and look at the timing to confirm I don't have her A tooth off.
This rough idle is why I put the new timing set on in the first place, I was disappointed when it still ran the same with the new timing tensioners, chains, and plastic guides.

 

You said you put a TB on it - is your scan tool capable of performing idle learn/reset procedures and if so, did you do that?

When you smoke test it, remove the intake tubing at the MAF sensor and block it off. At work I just stretch a rubber glove over them and use duct/electrical tape to seal it but a plastic bag will work as well. If you see smoke creeping out around your seal, do what you have to, to make it seal - the smoke will leak wherever it can, and if your seal is letting it out, it may not show an actual leak.

Also plug the PCV tubing at both valve covers - you want to keep the test isolated to the intake and that tubing gives the smoke an escape route into the crankcase.

 

Thanks for the smoke test tips. My scan tool has this Electronic throttle Rlrn, I'm assuming throttle relearn. Yes I did do that procedure.
Here is my PCM info. I have no clue if it is up to date or not. I couldn't find anything on my scan tool about throttle degree.