ECU - closed loop / open loop

[Gelf]

Richard, Adrian

Thanks for the advice

Andy

[Gelf]

I reduced the gaps down from wellover 0.7 until i just couldnt get the 0.7 gauge in the gap.

Been driving today, there is a difference. Plugs were a biscuit brown colour, but a bit sooty also.

[Richard L]

I learnt from the past that the rallycross cars ran between 0.4 to 0.45mm plug gap when tuned to produce 700-800 BHP.

Your result was consistant with plug gap. If the plugs were biscuit brown with some black markings, it appeared that the fuel didn't have enough time to finish burning before exhaust valve was opened. It could be ignition timing related or still a small amount of mis-fire.

Do you have means of advancing the ignition or reduce the plug gap further?

[Gelf]

Originally Posted by Richard L

I learnt from the past that the rallycross cars ran between 0.4 to 0.45mm plug gap when tuned to produce 700-800 BHP.

Your result was consistant with plug gap. If the plugs were biscuit brown with some black markings, it appeared that the fuel didn't have enough time to finish burning before exhaust valve was opened. It could be ignition timing related or still a small amount of mis-fire.

Do you have means of advancing the ignition or reduce the plug gap further?

No way of advancing ignition as im aware, with altering the map that is. Ive got a distributorless, direct ignition system.

[TurboGTi]

Originally Posted by Richard L

Your result was consistant with plug gap. If the plugs were biscuit brown with some black markings, it appeared that the fuel didn't have enough time to finish burning before exhaust valve was opened. It could be ignition timing related or still a small amount of mis-fire.

Richard the above statement made me realise how much fuel i'm wasting ... my spark plugs are always sooty ... hmmmm ii've already reduced my spark gap to about 0.6 or so so i'll try and pull some mS from the fuel injector opening time and also fiddle with the timing ....

Thanks its great to be apart of this

[Gelf]

Just ordered some Denso Iridium plugs to replace my Bosch 3 earth electrode plugs.

Standard plug gap is supposed to be 0.8mm / 1.0mm, which is probably where it was before i reduced them.

Anyways, Denso Iridium plugs are claimed to require at least 5000 volts less for the spark to jump the standard electrode gap.

[Richard L]

Originally Posted by Gelf

Just ordered some Denso Iridium plugs to replace my Bosch 3 earth electrode plugs.

Standard plug gap is supposed to be 0.8mm / 1.0mm, which is probably where it was before i reduced them.

Anyways, Denso Iridium plugs are claimed to require at least 5000 volts less for the spark to jump the standard electrode gap.

I am not really an expert on plugs, all I could remember it when I was playing with engine some five to six years ago, a standard plug is fine. I used to use get the single electrode type and I can play with the gaps easily. I rerely used the cold plugs because it fouled so easily.

These day, there are some many choices but as far as an engine's point of view, thery all work equally well.

It will be entirely up to you what plug is most suitable for you, but please before spending out a great deal of money just try the typical commercial low cost ones- you may be pleasantly surprised.