I just can't win.. yesterday it threw a coil 4 misfire, replaced coil pack and fix it for about 10 mins it was running like a dream til I got now a p0355 along with the 420 and 430.. my mechanic thinks it needs a whole new ECU.. are we missing something here?!?! All spark plugs coil packs are new even the fuel injectors.. no vacuum leaks
Back to rough idle
- Thread starter BrendanMc
- Start date
Have you checked the EGR Valve?
It wouldn't cause that code but it can definitely cause a rough idle. EGR valves usually start getting crappy as the car ages and gets high miles. They aren't too expensive and isn't too hard to replace but, can be time consuming.
The Powertrain Control Module is grounded to the coils, so, if you replaced the coils with anything but OEM Motorcraft coils, you might have a bad ground that is making your PCM go crazy.
joegr
Dedicated LVC Member
Also, check that the connector to the coil is latching correctly. Those latches break if you look at them wrong, and it would explain it working correctly for a little bit after you replaced the COP. The connector may have popped back out. I had to zip-tie some of mine.
Yea they aren't motorcraft.. but they have all been tested with a multimeter.
joegr
Dedicated LVC Member
That's a nearly completely useless test for the COPs. The main failure mode is (or at least used to be) high voltage breakdown of the epoxy in the coils. Ford sent out a TSB to the dealers saying that the only useful way to test the coils was to do an operational stress test and look at the results with an ignition scope.
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Marginal COPs could test fine, but as soon as you put the load & stress of different driving enviroments, they might not be able to fully operate within specifications. I had a shop put generic coils on my car (without my knowledge), and it was driving my poor PCM nuts, to the point where it started shifting erratically.
milehighmikey
Dedicated LVC Member
I'd strongly advise Joe's check posted above. As you get the engine running, if a connector is not latched, it can totally back out of the connector on the COP. Once a coil is not firing but the injector is still injecting, you then would see issues with the cat, p0420. Also just a DOA coil could be at play.
So I'm pretty sure changing the coil pigtail worked.. it was in bad shape, runs a lot smoother now and no more p0355.. but p0430 came back still. For the EGR... where the hell is it? I have a 2005 LS 3.0, its not where every other model has it out in the open.. does this model even have one?
joegr
Dedicated LVC Member
I'm not 100% sure, but I don't think that 2005 and 2006 3.0 had one.
That's not an EGR code anyway.
Catalyst System Efficiency Below Threshold (Bank 2)
joegr
Dedicated LVC Member
What did you replace them with. Most aftermarket cats are crap, and the LS is particular about it.
04_Sport_LS
Dedicated LVC Member
Vacuum leak can cause a lean misfire.
No vacuum leaks, 0355 is fixed I think from a bad pigtail, now back to 0430.
04_Sport_LS
Dedicated LVC Member
Well Joe is right about the P0430 code...
You have at least one defective catalytic converter. The aftermarket ones are known not to hold up bery long.
Some of the members on here have purchase the Magnaflow versions with good results.
Cheaper than OEM... but not as cheap as most aftermarket junk.
You have at least one defective catalytic converter. The aftermarket ones are known not to hold up bery long.
Some of the members on here have purchase the Magnaflow versions with good results.
Cheaper than OEM... but not as cheap as most aftermarket junk.
The LS really is the car version of a hot, spoiled woman. Buy her anything she might consider cheap and she'll buy Gucci with your credit card later
Couldn't a bad O2 sensor be giving wrong readings? The cats only have 30,000 miles on them
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Haha
milehighmikey
Dedicated LVC Member
Bad COPs can spoil a new cat by allowing raw fuel to be constantly dumped into the cats, so mileage is irrelevant in the case of running the engine with missing ignition occurring on one or more cylinders.
So it couldn't just be a bad O2 sensor?
joegr
Dedicated LVC Member
It's possible, but unlikely. This sounds like the typical case of shoot the messenger...