paschendale

Hi

I hope I can find some help on this Forum! I own a 2006 Roush Mustang 4.6 V8 Supercharged with CAI. I live in the UK.

I have a recurring error code - P0353 - Ignition Coil C Primary/Secondary Circuit that keeps triggering the OBD light on the dashboard.

I have so far replaced the spark plugs with Autolite Revolution HT0 plugs - gapped at arond .32mm, replaced the coil packs with Accel 140033 Super Coils and had the PCM checked for correct calibration and functionality by the Roush Representative in the UK - Mountune Automotive - They were the ones that originally upgraded the Stock GT that was imported into the UK (they were Roush UK at that time).

I have swapped Coil C with another coil, but the fault remains as Coil C - so it isn't the coil pack, it seems.

When the light is triggered there is no perceptable change to the way the car runs, apart from a very slight misfire type symptom when accelerating from low speeds in a high gear - but when accelerating hard, that symptom is not there. I get no misfire code and wonder whether it may just be a weak spark.

When the code is cleared, the car runs sweetly again. there is no real pattern to how many miles I drive before the light is triggered either. Sometimes it is after 40 -50 miles, somtimes 4 or 5 and sometimes 400!

Not sure where to to go next with eliminating probable causes.

Would appreciate any advice or assistance in resolving this issue

SMOKE

Have you contacted ROUSH HQ and explained the issue?
If I'm reading this right- Sounds like the PCM may need to checked and mapped for the changed plugs. I know it sounds tedious but have you documented these changes and made Mountune aware that the same codes pops despite the changes?
Gone back to stock and note if there's a code again?

paschendale

Yes, I explained to the guy at Mountune that we had changed the plugs and the coils and gave him the specs for both. He has assured me that the tune on the PCM is good and correct.

Someone has suggested that I check the wires to Coil C, especially at the the plug that connects to the coil as a weak connection may break intermittently and cause the fault code to come up...does that make sense to you?

I didn't notice any weakness to that plug when doing the swap over work, but I guess it only needs to be slightly weak to affect things - They are not particularly robust wires anyway, by the look of them!

Cheers
Pasch

paschendale

I do notice that the hard plastic Roush branded tubing that runs from the air filter to the throttle body sits very tighty ontop of plug C, which is just in front of and below the throttle body itself. When you remove the tube you can see that the wire to the coil has been under pressure from the tube pushing it down. I wonder if this might be the cause of the problem?

Would it be OK to modify this tube and by cutting it just before the moulded end that mates with the throttle body and just before the connection to the air filter, and replacing the main centre section that goes over the top of coil C between the two ends with more flexible rubber tubing of similar guage, less pressure would be placed ontop of the plug that fits into coil C?

Thoughts anyone?