2004 f150 5.4 rough idle
10-26-2015, 12:51 PM
#1
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2004 f150 5.4 rough idle
I have a 2004 fx4 with the 5.4 has rough idle. I changd phasers at which time had to re-time engine. Replaced all plugs with motorcrafts and all coil packs, changed cam positioning sensors and vct's. Truck runs great except for idling and codes p0351 and p0356 come up. I found a few post that talked about this but neither came to a conclusion. Can someone help me or direct me to a thresd I may have missed that may solve this. Thanks for any help
10-26-2015, 02:34 PM
#2
LightningRod
The codes you mention are quiet specific and directly related to your "rough idle" complaint - "Ignition Coil 'X' Primary/Secondary Circuit" where 'X" is cyl 1-8 expressed as 'A' through 'H' (for whatever reason I'll never understand). But forget that for another day.
The COPs are wired to 12 v on one side and the PCM pulls the other coil terminal go ground to 'fire' the coil. Code 351 says the PCM either sees no 12 volts applied to the coil or the coil draws NO current when it pulls the secondary terminal to ground.
You might trace / verify some wiring and electrical connections to do with effected coil circuits. Especially - have any of the little plastic "clips" on the coil connectors broken? I've had to replace four of them on mine because the rubber in the connector would cause it to back out until it would lose connection - and produce exactly the same codes.
------------ PostScript
I have temporarily placed a copy of the Engine Performance section of the 5.4L wiring diagram that might help trace wires back to PCM here. http://www.devoll.com/Public/f150-wi...-to-6-of-6.pdf You should be able to download and print or save to your computer. ( 17:12 pm CDT)
Hope this helps
The COPs are wired to 12 v on one side and the PCM pulls the other coil terminal go ground to 'fire' the coil. Code 351 says the PCM either sees no 12 volts applied to the coil or the coil draws NO current when it pulls the secondary terminal to ground.
You might trace / verify some wiring and electrical connections to do with effected coil circuits. Especially - have any of the little plastic "clips" on the coil connectors broken? I've had to replace four of them on mine because the rubber in the connector would cause it to back out until it would lose connection - and produce exactly the same codes.
------------ PostScript
I have temporarily placed a copy of the Engine Performance section of the 5.4L wiring diagram that might help trace wires back to PCM here. http://www.devoll.com/Public/f150-wi...-to-6-of-6.pdf You should be able to download and print or save to your computer. ( 17:12 pm CDT)
Hope this helps
Last edited by F150Torqued; 10-26-2015 at 06:16 PM. Reason: Added PostScript
10-26-2015, 09:57 PM
#4
I've replaced everything too and still rough idle. Got it checked and turned out to be the Intake manifold.
11-06-2015, 02:13 PM
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just to update. all plugs checked out fine. but just had new codes come up along with po351 and 356 there are now p0606 and p2106. which 606 is pcm and may be reason for 2106. Guess I am taking to ford to have them check pcm will keep updating. anybody else have these codes?