!HELP! 100mph then downhill

[04cobrafordboiz]

my setup is 2.75 pulley; i used a superchip tuner; borla cat-back; k&n cai; steeda idler pulley
the cobra pulls like a beast but for some reason once i get around 100mph it stops pulling feels like belt slip but then i noticed when i got home a misfire and it was a spark plug...... this is the second time the same spark plug does this and only after i get on it hard???:shrug::shrug:oke:

 

[Jroc]

I'm no expect but what kind of spark plugs are you running and what are you gaping them at? I run NGK TR6 plugs gapped at about .032. Maybe you should get a good dyno tune. I thought you were going to say you burn't up a piston or something.

 

[04cobrafordboiz]

no thank god actually i just changed all the plugs today it had some autolite crap i put some bosch platinum plugs should be a little better been alright so far just came back from drivin it pretty hard and everything seems good no misfire anymore,....i do need a tune though i hear its really worth the money especially running a smaller pulley...

 

[04cobrafordboiz]

why does that plug keep goiong out?:bash:

 

[Jroc]

no thank god actually i just changed all the plugs today it had some autolite crap i put some bosch platinum plugs should be a little better been alright so far just came back from drivin it pretty hard and everything seems good no misfire anymore,....i do need a tune though i hear its really worth the money especially running a smaller pulley...

I think thats your problem right there, you got the wrong spark plugs and without a costum tune on your modded Cobra your A/F is probably all messed up. With a blower pulley the size of yours a tune is required. You can mess a boosted car up if you just throw anything on there and don't tune for it. Get it done ASAP before you really tear it up.

Maybe your cars running rich or Lean and its killing your spark plugs. What do they look like when you take them out? Different spark plugs will produce a cooler or warmers spark than others. Like I said I'm no expect, but the wrong plugs and a bad A/F ratio can cause detonation. You want to run the cooliest burn plug you can without messing up your idle if I'm not mistaken.

IMO the NGK TR6 plugs are the best for these car. Some people will recommend a cooler running spark plug but the majority run this one.

http://www.lethalperformance.com/pa...tr6-ngk-tr6-v-power-spark-plugs-set-of-8.html

 

[Juruense]

Your car will die if you do not take corrective action:
1) get a tune
2) remove the bosch crap plugs and install Autolite (they are not crap!) or NGK plugs gapped at .032
3) DO THE COOLING MOD

Your car is not safe to drive and the damage may already be done. Good luck and nice job :nonono: