Hey all. So I bought a 15% pulley from ALTA and installed it. I also bought the stock JCW spark plugs to go along with them from ECS Tuning. They say they will work with the 15 and 17 % pulleys but I am having a MAJOR misfiring issue. What spark plugs is everyone running with the 15% pulley. I liked my old acceleration without the misfire stutters. Tempted to take the 50$ plunge and buy the Brisk Racing plugs right off ALTA's site. Tell me your opinion....

 

I'd check the plug gaps and make sure everything is torqued and fit properly. This happens a lot when pulleys are changed, the stock wires and coils have a hard time keeping up with the xtra boost.

 

Thanks for the reply but it's a 4 prong plug. How would I go about checking the gap percisely? Also what setup of coil and wires do you recommend if I keep the plugs? What setup if I change the whole system?(coil,wires,plugs)

 

Well if they are four prong just make sure they are tight, I'd start with replacing the wires that's usually the issue. Maybe move the wire that's misfiring to another cylinder and see if the misfire moves with it.

 

Make sure the wires are plugged into the correct spark plug. There will be a number on the terminal on the coil that corresponds to the cylinder number. These can be easy to mix up if you aren't careful, especially on #3 and #4. Here is a pic I found online that you can use as a reference.

 

The wires and coil pack have not trouble with the higher boost/temperature of a reduced sized pulley. In fact, many aftermarket parts are worse than the stock. You might consider some NGK Iridium plugs--if yours are worn, than they will reduce the risk of misfiring. Save your money on the other bits.

 

+1 for Eric

I've had misfire issues with my R53 twice and both times new plugs solved it. And another +1 for Eric's heat range 7 plugs.

 

I was just having a P0300 Multi Misfire issue after changing my pulley because they didn't send me the right belt size. I got the right belt size from NAPA and cleared my issue right up.

May not be the same issue as yours being a P0302 but something to think about

I picked up a 060535 belt.

 

I upgraded to 15% pulley with the JCW plugs and had the same issue, but mine was calling out a misfire on cylinder #4.
I did the following..

- Checked resistance on all wires (2 yrs old). They all showed similar numbers, figured they were ok.

- Checked compression on all cylinders, all were consistent as well.

I knew that the car was getting air, spark also wasn't an issue. Last thing to check was fuel. I noticed that there was some rust around the injectors, the pressure regulator was rotting out as well.

So I pulled the intake mani out to remove the fuel rail so that no rust would fall into the compression chamber. When pulling the 4th injector out, it just snapped in half........ Had to use a rubber mallet on two others as they were seized to the manifold. Gotta love New England winter...

So I picked up a clean, used fuel rail that came with OE injectors and regulator, was $70 shipped. Bolted everything back up and fired her up. It idled and drove fine from there on. I also replaced my fuel filter (messy job). Everything has been well for about a month now (knock on wood). I guess I'd recommend checking the wires and perform a visual inspection on your fuel rail..
Let us know what you find..