becutler

I'm brand new to the forum here but I have snooped around the forum for years and it has helped me tremendously. However, I have been unable find the solution to my issue.

Please don't kindly point me to the search bar.

Ok so here's the truck: 2007 Scab 4.6 XLT. On a cold start and sporadically at low RPM times like parking lot maneuvers and turning, the truck will sometimes shudder or buck like an old carburetor car in need of a tune up. Also, the idle speed itself can be jumpy. This isn't "normal" modular Ford motor bad idle, this is extreme, and a few times the truck has actually stalled. Once the truck gets some persuasion from my right foot, performance at speed is flawless. Usually I have an Edge Evo tuner on my truck but it has been set to Level Zero (factory) through this process

No codes are present.

In chronological order, the following has been addressed chasing the problem. An asterisk (*) denoted items that seemed to temporarily help the issue.

Premature oil change
MAF cleaning*
TB cleaning
FORD SERVICE:

• general inspection
• injector cleaning
• TB "position reset"
• spark plugs
• inline fuel filter replacement
• new PCM flash

FPDM replacement*
Transmission Fluid check
MAF cleaning, round 2


So as you can see, the usual gremlins of plugs/coils, MAF, TB, fuel filter, and injectors have all been addressed, to no avail. I'm at my wits' and wallet's end as to how to move forward.

EDIT: (the following was originally a response to Joe which can be seen below. I believe it clarifies my issue) I realize now that the term "poor idle" may be misleading. The truck does not do crazy things while sitting still. Rather, it acts up at parking lot/ intersection speeds. It shudders when coming to a stop. It shakes and bogs while applying throttle mid-turn at a "+" intersection. It bucks and shifts wildly as it leaves a stoplight. And all of these symptoms can be bypassed by planting to go pedal to the floor until cruising speeds are reached.

techrep

iTrader: (1)

if cleaning the maf helped .. i would replace it.. $40 rockauto

becutler

It's also worth noting that the problem seems worse in temperatures below 40°

joe mcmillan

What is the idle speed in park and then in gear? How much does it vary low to high?
Have you done the complete relearn process? If not, need to go through this completely.
Type of air filter?

becutler

At 75*T
Park idle settles at 1050 rpm after jumping upwards of 1200 at start up. Drive idle 850 rpm at start up. Warm drive idle 550 rpm.

These numbers are higher than I have experienced over the winter. I know I've seen cold Drive idles around 650. On these colder mornings, coming to a stop at the exit of my complex would often, but not always, cause an rpm fluctuation of about +-100 on the 2-1 downshift coming to a halt. For example, applying brakes and tach at 600, "clutch release" occurs and tach rises to about 700 rpm, shift completes and the tach dives south of 500 and the truck coughs, shudders, and finally regains its composure as it comes to a complete stop. I can usually tell within 10 seconds of cranking the truck in the morning if it's going to act like a COPD patient or a happy kitten.

I have done the relearn process that I found on this forum twice but not since the new FPDM, which was a corroded heap and had rainwater pooled up inside, in contact with the circuit board. The process I found was a series of minutes with no accessories idle, all accessories idle, and driving.

The truck has a K&N CAI with the K&N filter. The filter was recently cleaned and oiled, but the directions were followed to a tee and the MAF has been cleaned twice since the oiling, so I don't believe the filter oil is causing the issues.

joe mcmillan

I was not concerned about the cold idle speed. It may be significant.
My 4.6 idles @525 in Drive at operating temp. Very smooth and no fluctuation.
Did your truck idle smoother before the K&N CAI?
I ran a K&N filter for a period of time and do not recall any idle issue. Returned to paper filter as I learned more about the K&N and possible issues.
Do you ever get any CEL?
How many miles?
It may be worth it to go through the complete relearn process again:

Now that you've cleaned your TB do a TPS reset, it won't hurt a thing and may improve your Throttle response also.
Put Key in the ignition and turn to the ON position, remove the drivers side floor mat, don't start motor, let the bells and chimes do their thing and when they finish push the peddle to the floor and then release the peddle to come back up, turn key to the OFF position, now repeat two more times.
After doing this start the motor and go for a ride and see if it's as good as new!
PS. don't start the motor and floor it, just drive it like you want to keep it!
----------------------------
This is used for clearing codes by disconnecting the battery cable for 15 mins. Be sure there is no cell phone chargers/lap top/anything like that plugged in. While cables are disconneted I always cycle the key. And turn the head lights on. Then follow it up by the relearn process.

Battery relearn
Because your vehicle’s engine is electronically controlled by a computer,
some control conditions are maintained by power from the battery. When
the battery is disconnected or a new battery is installed, the engine must
relearn its idle and fuel trim strategy for optimum driveability and
performance. Flexible fuel vehicles (FFV) must also relearn the ethanol
content of the fuel for optimum driveability and performance. To begin
this process:
1. With the vehicle at a complete stop, set the parking brake.
2. Put the gearshift in P (Park), turn off all accessories and start the
engine.
3. Run the engine until it reaches normal operating temperature.
4. Allow the engine to idle for at least one minute.
5. Turn the A/C on and allow the engine to idle for at least one minute.
6. Release the parking brake. With your foot on the brake pedal and with
the A/C on, put the vehicle in D (Drive) and allow the engine to idle for
at least one minute.
7. Drive the vehicle to complete the relearning process.
• The vehicle may need to be driven 10 miles (16 km) or more to
relearn the idle and fuel trim strategy along with the ethanol content
for flexible fuel vehicles.
• If you do not allow the engine to relearn its idle trim, the idle quality of your vehicle may be adversely affected until the idle trim is
eventually relearned.

becutler

The CAI was installed by the PO, it has been on the truck all of my ownership. 130k miles. No CEL, just a monkey wrench light the few times the issue has caused a limp mode situation. Clears with a restart.

I realize now that the term "poor idle" may be misleading. The truck does not do crazy things while sitting still. Rather, it acts up at parking lot/ intersection speeds. It shudders when coming to a stop. It shakes and bogs while applying throttle mid-turn at a "+" intersection. It bucks and shifts wildly as it leaves a stoplight. And all of these symptoms can be bypassed by planting to go pedal to the floor until cruising speeds are reached.

joe mcmillan

That monkey wrench (check engine) light is producing a code every time it comes on. Just because there is no wrench when you restart does not mean there is no code.
Check for codes with your tuner. As long as the battery has not been unhooked (or the codes cleared via manual input to your tuner) there will be codes. Those will help with diagnosis.
I believe you said you have an Edge Evo - correct?
Use it for codes, also use it in #2 mode for better transmission management.

becutler

I forget the number, but the few times it has thrown a wrench and gone into limp mode (this was before the FPDM and the trip to Ford) the code was something to the effect of "over torque situation." Did some digging back then. The Mustang guys get it a lot, and it doesn't tell you much. It happens when the computer thinks the motor is producing an unsafe amount of torque.

The Edge just made my problem worse. Before this wild goose chase I used to run #3 mostly. The problem became progressively severe, so I backed down to 2, and then to 0. Each step decreased to severity of the hard shifts/shuddering. The truck has been on #0 since Ford reflashed the ECM.

becutler

As an aside, I thought the wrench was for "perform maintenance" and the CEL was the one that actually looks like a crate motor. I may be splitting hairs for no reason, just wanted to check.