4.6 L random misfire on cylinder 2, it's not the coil-pack : 2003 Lincoln Aviato

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  #1  
Old 03-02-14, 03:41 PM
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Wink 4.6 L random misfire on cylinder 2, it's not the coil-pack : 2003 Lincoln Aviato

Engine light flashes intermittently. I bought a new coil pack and it didn't help, fortunately they let me return it. I put in all new plugs to eliminate that possibility. I swapped out the crankshaft sensor, 1 o2 sensor, ran several cans of seafoam and various other cleaner in gas as well as crankcase.Its getting fuel. When get to highway speeds it smooths out, not sure if it's actually firing properly then or just the speed makes it appear to get better. I had a mechanic pull the valve cover and all the valve springs look good, of course we couldn't see if there was any carbon buildup. I am lost. The car has power but slightly hesitates at takeoff and slightly skips at low road speeds. I do burn premium but i believe the previous owner burn 87 octane. The previous owner seem to have done most of the maintenance on a regular basis, Mileage is a well taken care of 132,500. I tried to include everything I have done to help isolate the problem. Any advice would be greatly appreciated.
 
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Old 03-02-14, 03:59 PM
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Have you had the codes checked?

I would check all vacuum hoses, pcv (make sure it's sucking) and iac valve (remove and clean as needed). I still have a similar problem on my 4.6L V6 F150 after replacing plugs, wires, coil pack... but my coil pack was bad 2 of 6 cylinders anyway (tested primary and secondary resistance with voltmeter). Waiting for warmer weather to check out the rough idle. (-18F tonight)
 
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Old 03-02-14, 04:09 PM
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Good idea. I wish you the best and if I find a solution to my issue I will forward the information. I love people helping people. Have a great evening.
 
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Old 03-02-14, 04:15 PM
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I forgot to mention also cleaning the MAF sensor, between the air filter and intake. Best to you as well.
 
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Old 03-02-14, 04:39 PM
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1st thing to do is to read codes. Assuming, this was done?
2nd is, to eliminate coil pack, you simply swap one in question with one known to be good. If issue follows the coil pack, it's coil pack.
Under circumstance of coil pack being good, spark plug being good, and cylinder in Q still misfiring, you have 2 options left:
- ECM is going bad
- fuel injector mulfunction for the particular cylinder.
As it not only takes spark to fire, it also take petrol and oxygen.
I'd say, take injector out and clean it.

https://www.youtube.com/watch?v=dp-ECEpN52k

https://www.youtube.com/watch?v=7aT4S1lIBAY

Misfires can be caused by anything from fuel delivery to a mechanical problem. For me, the first step in diagnosing the source of a misfire is to determine if the misfire is specific to one cylinder or several. An easy way to do this is with a power balance test.
Solving Automotive Performance Issues - Eric The Car Guy- Stay Dirty!
 
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Old 03-02-14, 05:44 PM
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I bought a new coil pack and it didn't help
I cannot say for sure about a 2003, but in the late 90s a 4.6 V-8 had two coil packs, one at the front of each cylinder bank. Did you check both coil packs for cracks? It's a common issue.
 
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Old 03-02-14, 07:30 PM
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just to ask when you replaced #2 coil where on the engine was it. i find some people dont really know that ford count in order starting with pass 1234 drivers 5678.
 
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Old 03-03-14, 02:57 AM
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it was the 2nd back on passengers side
 
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Old 03-03-14, 04:08 AM
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I had the same thought as Igor - possibly a bad/clogged injector.

And the 87 octane fuel would not be a factor.
 
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Old 03-03-14, 04:16 AM
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Possibility [Note: the other TSB referenced is pretty extensive and probably not DIY]:


TSB 06-5-13

ENGINE MISFIRE WITH DIAGNOSTIC TROUBLE CODE (DTC) P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, AND P0316.Publication Date: March 7, 2006

FORD:
2003-2004 Mustang
LINCOLN:
1999-2004 Navigator
2002-2003 Blackwood
2003-2005 Aviator
MERCURY:
2003-2004 Marauder

ISSUE:

Some 1999-2004 Navigator, 2002-2003 Blackwood, 2003-2005 Aviator, 2003-2004 Marauder and 2003-2004 Mustang vehicles built before 12/19/2004 equipped with 4.6L 4V/5.4 4V engine may exhibit a runs rough, lacks power, and engine misfire, prompted by a MIL light and DTC codes P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, and P0316.
ACTION:

Diagnose engine for engine misfire concern. If diagnostics determine an engine misfire which is characterized by leakage through exhaust valve(s), only replace the affected cylinder head(s).
SERVICE PROCEDURE



FOR VEHICLES WITH RUNS ROUGH/MISFIRE CONDITION:

Perform relative compression check on all cylinders. If abnormal, check cylinder leakage and actual compression for "low" cylinders refer to Workshop Manual (WSM), Section 303-00.
If leakage/compression check indicates a valve train concern, per valve train diagnostics in WSM, Section 303-00, replace cylinder head and cam assembly, pipe plugs and timing chain tensioner, per procedure outlined in WSM, Section 303-01.
If cylinder leakage and compression tests are inconclusive, perform misfire diagnostic, per TSB 05-22-8.
NOTEO NOT TRANSFER SPARK PLUGS. INSTALL NEW SPARK PLUGS IN REPLACEMENT CYLINDER HEAD AND CAM ASSEMBLY.

NOTE:THE ENGINE MISFIRE CONCERN IS TYPICALLY EXHIBITED ON THE LEFT HAND CYLINDER HEAD AND RARELY ON THE RIGHT HAND CYLINDER HEAD. UNLESS CONFIRMED, THE RIGHT HAND CYLINDER HEAD SHOULD NOT BE REPLACED AS AN "EXTRA MEASURE" SERVICE PRECAUTION.

NOTE:THE REPLACEMENT CYLINDER HEAD WILL NOT IMPROVE OR REDUCE ENGINE HORSEPOWER OR TORQUE ABOVE ADVERTISED LEVELS.
 
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