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Ba Xr6 Turbo Missfiring Under Wot - With New Coils And Plugs


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Hi guys


Hoping someone might be able to give me an idea where to start with this...


2003 BA XR6 Turbo, 125000KM. I am the second owner since I got it at 120000KM where it was in stock standard form around 8 months ago.


A week after owning it I took it to HorsePower Factory and got a basic custom dyno tune, cold air intake, with the factory fuel injectors and valve springs left alone.


All was well for 3000KM and then the gearbox started slipping, so I had the BTR 4 speed rebuilt to OEM spec less than 2000KM ago. When I got it back the car was going great, feeling a lot of responsive and agressive.


A few weeks later, it started missing at idle so I swapped the coil packs and spark plugs for new genuine Ford ones. Since then, it idles perfectly, but I now get a loud backfire at wide open throttle when shifting into 2nd. And just now tonight I noticed it is missfiring fairly badly around 50% of the time when WOT from 80kph... sometimes its a short missfire and it clears and keeps pulling hard, othertimes its spluttering really badly so I back off the throttle. Tonight was the first time I had tried WOT from 80KPH since doing the plugs/coils a month ago.


Aside from that, it drives great as my daily driver, and sits on 110kph towing my dirtbike trailer no worries.



I have checked all the air intake hoses and everything is still in place since I did the plugs and coils. I am wondering if it is something to do with the spark plug gap? In my receipt from HPF it shows "re-gap spark plugs as required"... so perhaps these new OEM ones aren't fitting the tune? Or perhaps I have a faulty coil pack, which would be bad luck as they are brand new.


Unfortunately I threw out the old coil packs and plugs.


Is it common to modify the spark plug gap when tuning these? Should I just ask HPF to re-gap some new plugs for me?


Thanks in advance for any ideas you have, love driving this car and looking forward to sorting this out.


Cheers,

Tim

  • To Loud
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Please take this with a grain of salt, I am no expert, but I think this may be the valve springs mate.

Can Luke please tune in and advise?

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If your boost is higher than standard you need to gap your plugs down

.7 or .8 gap should be good

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  On 12/12/2015 at 1:16 PM, Wilko16 said:

If your boost is higher than standard you need to gap your plugs down

.7 or .8 gap should be good

^WHS

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As others have said. It's more than likely plug gap. What ones did you install

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  On 12/12/2015 at 9:24 AM, timburns23 said:
A few weeks later, it started missing at idle so I swapped the coil packs and spark plugs for new genuine Ford ones. Since then, it idles perfectly, but I now get a loud backfire at wide open throttle when shifting into 2nd. And just now tonight I noticed it is missfiring fairly badly around 50% of the time when WOT from 80kph... sometimes its a short missfire and it clears and keeps pulling hard, othertimes its spluttering really badly so I back off the throttle. Tonight was the first time I had tried WOT from 80KPH since doing the plugs/coils a month ago.
Cheers,
Tim

Yeah sounds like valve springs /end italics

Also cheers and Tim in the one post, how did we miss that?

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  • To Loud
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Luke, that is why I thought it was valve springs, due to that line in Italic.

It's gonna be a pain in the ass to get done, may as well upgrade a few other parts, if you got plans to upgrade and get the valve springs done to.

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OP changed plugs and Coils. Problem started. Regapping the plugs to the correct range is the place to start.

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