2001 4.6 misfire on one cylinder

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My son in law has a 2001 F150 with the Triton 4.6 engine. It has 190,000 miles on it. A few weeks ago he had a misfire that set a PO302 code. He changed the COP on cylinder number 2 and that cleared the problem.

Now he has a PO307, cylinder number 7 misfire. He and I installed a new COP and put a new Motorcraft plug in 7.
It still generated a PO307. We swapped the new COP for one of the other COP's and still got a 307.

We then put a new fuel injector in that cylinder. That didn't help.

I connected a vacuum gauge to the brake booster hose and at idle the truck has a steady 18 hg of vacuum.

I realize I need to do a compression test at this point. Thats going to be a hassle on this truck. Is there anything else for me to check?

I can check the fuel pressure tomorrow but that shouldn't be on only one cylinder if it's low should it?

The misfire is severe enough to be noticeable in the cab.

Thanks,
Terry
 
Sounds like that cylinder is having trouble for sure... Compression test is what I would suggest given all that you have tried.
 
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Originally Posted By: Nick1994
You didn't say anything about spark plug replacement...


"He and I installed a new COP and put a new Motorcraft plug in 7"
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I would check for fuel and spark at that cylinder. Just because you replaced them doesn't mean some electrical issue didnt rear its head and they are not working.
 
Originally Posted By: Colt45ws
I would check for fuel and spark at that cylinder. Just because you replaced them doesn't mean some electrical issue didnt rear its head and they are not working.


I have to pull that plug out to do a compression test, so I suppose I could crank the engine with the plug out and grounded just to make sure the coil is getting a signal.
 
Originally Posted By: StevieC
Originally Posted By: Nick1994
You didn't say anything about spark plug replacement...


"He and I installed a new COP and put a new Motorcraft plug in 7"
13.gif

Oooh! I thought he was still talking about number 2

Still weird to replace only 1spark plug...
 
Originally Posted By: terry274
Originally Posted By: Colt45ws
I would check for fuel and spark at that cylinder. Just because you replaced them doesn't mean some electrical issue didnt rear its head and they are not working.


I have to pull that plug out to do a compression test, so I suppose I could crank the engine with the plug out and grounded just to make sure the coil is getting a signal.

If you hold the gas pedal to the floor, it activates "flood clear" mode in the ECU and will not operate the injectors, so you can crank without it starting.
Good for compression check, too.
 
Originally Posted By: Nick1994
Originally Posted By: StevieC
Originally Posted By: Nick1994
You didn't say anything about spark plug replacement...


"He and I installed a new COP and put a new Motorcraft plug in 7"
13.gif

Oooh! I thought he was still talking about number 2

Still weird to replace only 1spark plug...


No worries...
cheers3.gif
 
This is when you really need a nice bidirectional scan tool so you can run a relative compression test, monitor the cam signal, et cetera. I think the PC version of the ForScan app can do relative compression actually.
 
Originally Posted By: Colt45ws
I would check for fuel and spark at that cylinder.


Why do that when you can throw parts at it ?
 
So, you know for sure that it's cylinder number 7? If you disconnect that cylinder, there is no/minimal change?

Or is it that the other plugs are old and not firing well?
 
Just for info's sake:
My friend has a '97 F-150 w/ 4.6l and he has the pair of 4 socket coils with spark plug wires going to each plug.
Since he bought the vehicle Fords come up in threads (like this) and in conversation and it appears to me that Ford used coils and COPs all over the year range of the 4.6 and 5.4 engines.

There seems to be no rhyme or reason to it.

What is a "connector hat going to the COP", a plug of sorts?
 
Thanks for the replies. A special thanks to Ethan1 and Trav, both your suggestion were helpful. I have not yet managed to fix the truck unfortunately.
What I have done:
Pulled the COP and used a jumper cable and spark plug to verify it does have spark.
Used a compression tester and got 120 PSI with a cold, dry engine. When I was doing the test I neglected to open the throttle, nor did I add oil to do a wet test. Well, I am a rookie...so this didn't really tell me much.

Connected a light to the fuel injector connector. It flashed as the engine ran.

Installed Forscan on my computer. This truck has MANY problems:

===PCM DTC P0307===
Code: P0307 - Cylinder #7 Misfire Detected

Module: Powertrain Control Module

Diagnostic Trouble Code details

Cylinder #7 Misfire Detected

Ignition System

Fuel System

This DTC may be caused by :

Blocked kinked or crushed fuel lines

Fuel contaminated

Evaporative emission control system malfunction

EGR system fault.

Base engine fault

Check for any other codes that may cause a misfire.

===END PCM DTC P0307===

===RCM DTC B1884===
Code: B1884 - Passenger Air Bag Disable Warning Lamp Circuit Failure

Module: Restraint Control Module

Diagnostic Trouble Code details

Passenger Air Bag Disable Warning Lamp Circuit Failure

--- Possible Causes --------

-PAD Warning Lamp Inoperative

-Suspect
-Warning Lamp -Electronic Crash Sensor (ECS) Module

Suspect a short in the wiring.

===END RCM DTC B1884===

===RCM DTC B1318===
Code: B1318 - Battery voltage Low

Module: Restraint Control Module

Diagnostic Trouble Code details

Battery Voltage Too Low

--- Possible Causes --------

- Battery Voltage below 9.6volts

-Suspect Battery state of charge Charging system

===END RCM DTC B1318===

===GEM DTC B1365===
Code: B1365 - Ignition start circuit battery short

Module: Generic Electronic Module

Diagnostic Trouble Code details

Ignition start circuit battery short

===END GEM DTC B1365===

===GEM DTC B1431===
Code: B1431 - Wiper Brake/Run Relay circuit failure

Module: Generic Electronic Module

Diagnostic Trouble Code details

Wiper Brake/Run Relay circuit failure

--- Possible Causes --------
This code can be generated by:

-Ground/Short Front Wiper RUN/PARK Relay

-Open/Front Wiper RUN/PARK Relay


-Suspect Front Wiper RUN/PARK Relay

-Suspect Generic Electronic Module

===END GEM DTC B1431===

===GEM DTC B1434===
Code: B1434 - Wiper speed relay coil circuit failure

Module: Generic Electronic Module

Diagnostic Trouble Code details

Wiper speed relay coil circuit failure

===END GEM DTC B1434===

===GEM DTC B1458===
Code: B1458 - Wiper washer pump motor relay coil circuit failure

Module: Generic Electronic Module

Diagnostic Trouble Code details

Wiper washer pump motor relay coil circuit failure

===END GEM DTC B1458===

===GEM DTC B1840===
Code: B1840 - Wiper Front Power Circuit Failure

Module: Generic Electronic Module

Diagnostic Trouble Code details

Wiper Front Power Circuit Failure

--- Possible Causes --------
This DTC can be generated by:

-Ground Short Front Wiper Power Feed

-Open Front Wiper Power Feed

-Suspect Generic Electronic Module

===END GEM DTC B1840===

===GEM DTC B1428===
Code: B1428 - Safety belt lamp circuit failure

Module: Generic Electronic Module

Diagnostic Trouble Code details

Safety belt lamp circuit failure

--- Possible Causes --------
This code can be generated by:

-Ground Short Driver's Seat Belt Lamp

-Open Driver's Seat Belt Lamp

-Suspect Driver's Seat Belt Lamp

-Suspect Generic Electronic Module

===END GEM DTC B1428===

===GEM DTC P0500===
Code: P0500 - VSS sensor circuit fault.

Module: Generic Electronic Module

Diagnostic Trouble Code details

VSS sensor circuit fault.

Open VSS circuit.

Shorted VSS circuit.

This DTC may be caused by :

Suspect VSS.

Worn or Damaged VSS drive gear on transmission output shaft.

Suspect PCM.

Faulty or damaged instrument cluster module.

===END GEM DTC P0500===

===GEM DTC B1318===
Code: B1318 - Battery voltage Low

Module: Generic Electronic Module

Diagnostic Trouble Code details

Battery Voltage Too Low

--- Possible Causes --------

- Battery Voltage below 9.6volts

-Suspect Battery state of charge Charging system

===END GEM DTC B1318===

===GEM DTC B1315===
Code: B1315 - Battery saver relay coil battery short

Module: Generic Electronic Module

===END GEM DTC B1315===

===RAP DTC None===
Successful DTC reading, no error codes found

Module: Remote Anti-Theft / Personality Module

===END RAP DTC None===

===ABS DTC None===
Successful DTC reading, no error codes found

Module: Antilock braking system

===END ABS DTC None===

I have the truck connected to a battery charger at this time. It may be low from cranking and not starting, or starting for a few seconds and being shut off.


I would really like to help my son in law, he's a good guy. But this is beyond my ability.
 
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Most of those codes look old from a previous one-time event like running the battery down. Erase them and see which come back.

The cylinder 7 issue is the main one since it's causing a noticeable performance problem. On any old engine it is good to compression test all the cylinders properly (warmed up and with throttle open) so you know where you stand mechanically.
 
Just for the heck of it change the plug again. It would be very rare and I have only had one or two in my whole career that were truly DOA but its worth eliminating if nothing else.
 
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