PO353 WRONG CODE?

[djrythmn]

OK please help if you can. My wife has a 2007 fusion w/ 3.0 V-6 ( 63000 miles) She gets home and 2 hrs late I take her car to go drop off movies (it was raining) The car boggs down wont even go 10 mph.

I go to Auto shack to borrow their scanner. (yeh engin light came on) I got the code PO353 third cylindar coil, first/secondary . I'm not up on all the computer stuff (and probably should have a professional do this but I don't have the cash. So I researched on line and went thorough the following steps.

1. I replaced that plug. (still missfiring)

2 Replaced all the plugs. (Still misfiring but not as bad about 85% of where the car should be)

3 replace coil pack for no3 Cyl. ( Still nothing)

4 switched new coil pack to another cyl to make sure it worked (Yes it did)

5 pulled connectors one at a time from front bank coils to see difference in rpm change (all three worked)

6. Was able to reach underneath intake and pull connector on number 3 coil pack (no change plugged or unplugged. still missing.

 

cylindar order firewall

1-2-3

4-5-6

radiator

 

I have no idea at this point nor do I have the tools to go any further. I take it to a shop and they tell me what I already know except for this They tell me the firing order is

 

 

1-3-5

2-4-6

Ok that would explain that I changed the wrong coil pack but it doesn't explain why i didn't get spack from (what I thought was number 3 coil)

 

HELP!!!! Is my firing order right or his? He said that was the order ghe got from his scanner. but I haven't been able to fing anything online to corroborate this........

[FusionDiffusion]

The correct cylinder numbering is:

 

Firewall

1-2-3

4-5-6

Radiator

 

If you replaced both the plug and the coil on #3, it's likely you have either a wiring problem or a bad PCM. You should confirm you are getting power to #3 coil and that the coil is being turned on and off by the PCM.

 

There is a TSB for this issue that specifies replacement of the PCM and all six coils: http://www.revbase.com/BBBMotor/TSb/DownloadPdf?id=176650

 

Did the original #3 coil show any signs of damage?

Edited February 27, 2013 by FusionDiffusion

[djrythmn]

no there wasn't any damage i could tell .. and i took the coil from 3 and placed it in 5 and it worked.

[djrythmn]

Since 3 is in the back. how do I check for spark when fully assembled? or how can i check with intake off?

[FusionDiffusion]

You want to check for power on the connector, not spark. You should be able to unplug #3 and access the connector with the intake manifold on, right? With the key on you want a constant 12V with the key on on the gray/yellow wire and you should have a pulsed ground on the the other pin (white/brown wire) with the engine running. You can check these with a $5 test light.

[djrythmn]

Thank you I'll grab that from the store. But one more thing. The strange thing is. what would make a scanner assign the wrong code? The mechanic told me (as I argued the firing order. That he cleared the codes and I by one went thru the front bank which would be 4-5-6. He said when he unpluged each seperate one for what we think as 4 he'd get the code 352 then he'd clear the codes again and 354 for what we think is 5. Did he have a faulty scanner or is there another problem I'm not seeing?

[FusionDiffusion]

He was either reading it wrong or the PCM is on the fritz. Coil unplugged should equal the coil circuit code you get. If not then they're something screwed up (either the wiring harness, the PCM, or the mechanic). There might also be a delay between when he unplugged the coil and when the code shows up.

[fusionfamily]

Just as a side note. Don't confuse firing order and cylinder location.

Cylinders are as follows:

 

Firewall

1 2 3

4 5 6

Radiator

 

Firing order is 1-4-2-5-3-6

 

As for checking the coil - bit of a pain in the butt to do... but you can either check power going to it with an oscilloscope (I wouldn't recommend a test light becaue you really can't tell what the signal looks like. Just cause the light flashes accordingly doesn't mean there isn't resistance in the line causing the coil to not fire correctly - ie: dwell is too short, etc), or do a 'poor man's' stress test by turning the coil over - pointing straight up - and see if it still fires.

 

Or the PCM could be screwed (faulty coils cooking the PCM when the magnetic field collapses and the voltage spike in the primary isn't contained by the diode).

 

Or an issue with other wiring in the area causing enough interference to cause the coil not to fire / fire erratically, etc.