spark plugs?

is it because it is platnum not copper? or is it the 103 plug? If i were to replace them what should i go with?

Platinum doesn't conduct electricity as well as copper. Thus you can achieve higher energy with straight copper electrodes vs platinum coated electrodes.

That all being the same, if they are gapped to .035 they shouldn't have an issue up to 15psi as lots of folks have run double platinum plugs and 15psi in the past without issue.

The best plug is a standard copper plug that you simply change regularly.
 
I am one of those that runs Plat and 15PSI with no problems, but mine is basically a DD with a butt load of power.
 
well i am using a 99 mustang block with the super coupe heads. the exhaust ports are gasket matched, and i am running stock boost 10-11psi. the plugs are app103 (double platnum) and they are gapped to .035". i have a screamin demon coil and ford racing 9mm wires. the sputtering is very bad in 1st and 2nd gear (5100 rpms) and then not so bad in 3rd and 4th. so i narrowed it down to plugs or coil. there is never been a flashing check engine light when the sputtering happens wich in the back of my mind wants to rule out coil, and I know i am getting gas. before i did the swap i could go to 5800 rpms no problem.
 
Those coils have been known to cause those exact issues for several folks around here. Get a stock one and put it on.. besides, those coils are of no benefit over the stock ones as the stockers perform perfectly even for those running 400+rwhp.

Fraser
 
Those coils have been known to cause those exact issues for several folks around here. Get a stock one and put it on.. besides, those coils are of no benefit over the stock ones as the stockers perform perfectly even for those running 400+rwhp.

Fraser

I'm using a stock coil and wires making 350+rwhp.
 
Those coils have been known to cause those exact issues for several folks around here. Get a stock one and put it on.. besides, those coils are of no benefit over the stock ones as the stockers perform perfectly even for those running 400+rwhp.

Fraser

thank you!!!
 
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