jrogers

I have euro CIS and generally run pretty rich. I currently use Denso W24ESR but I think I am fouling them (high RPM full throttle miss, intermittently). Any recommendations for a better plug, or comments about what I am currently using?

Here is a dyno sheet on the motor.





Thanks,

Jim

Geoffrey

I'd use a Bosch W4CS plug.

m42racer

[QUOTE=jrogers;6169481]I have euro CIS and generally run pretty rich. I currently use Denso W24ESR but I think I am fouling them (high RPM full throttle miss, intermittently). Any recommendations for a better plug, or comments about what I am currently using?

"Think" your fouling could be the word you could either die or live from.

Do a hard run at full boost at peak torque RPM then do a full Ignition cut. No idling. Look at # 3 Plug. If you do not know how to read a plug show it to someone who does. DO NOT change plugs just because someone here say so. They have no clue if you need to or not. They will have their favorites, but that does not mean you need to use them. You have to make sure it is OK at full power. Often the plug is just right at full power but can be fouling at idle and part throttle. Then your choices are more choice of firing end and position not so much heat range.

ASK, if your not sure. Run a plug too hot and you could be replacing more than just plugs.

Jitters

Hey Geoffrey!

Is your recommendation based on the increase in displacement from stock? I ask because it was suggested that I use a Bosch W3PO plug, which I believe is the standard plug for the 3.3. I'm also running a 3.4 and would like to run the correct plug as well.

Thanks,

Jitters

Geoffrey

I agree with what Simon mentions above in the selection of spark plugs. However, it has been my experience that a stock heat range plug Bosch W3DPO is too cold for the 930 engine and a heat range of '4' works much better. The W4CS last a long time and are a better material than a stock plug and I've had issues with platinum plugs in the past on 930 engines.

I don't know anything about the plug you are currently running, however, if the engine is missing and fouling plugs, I'd look for something else mechanical or something set incorrectly in the fuel system before assuming it was the plugs and spending $120 for a set.

Jitters

Thanks Geoffrey for the feedback. I'll give them a try.

Cheers,

Jitters

m42racer

Totally agree. Good advice. Plugs should be the last thing to check, once all other functions have been.

Millhaus

I also run the WC4S plugs in my 1980 Euro CIS stock.

No issues. The spec plugs fouled out too much.