[Diy_efi] those bosch 4 point plugs

[Dustin Lof]

Mike I dont think it is the plugs fault, sounds like
your coil output is low.  A combination of the plugs
and a lean mixture is working your coil to the max.  A
hotter coil will do it for you.   Dustin Lof

--- Mike <niche at iinet.net.au> wrote:

> Hi chaps,
> 
> Some diagnostic experience for yesterday, Sat.
> 
> Have tuned ignition leads on my 3L turbo (same
> resistance of 2Kohms
> for each leg) and noticed the new bosch 4-point
> plugs have trouble
> firing smoothly under boost. So went to ngk
> 'ordinary' plugs
> and no problem at all, even up to 10psi of a leaner
> mixture.
> Over here the bosch 4-point at AUD55 per set of 6 vs
> ngk at AUD24.
> 
> The complication is that I am running a bit leaner
> than normal,
> so its prob not that the bosch 4-point are faulty
> but that they
> wont ignite a leaner charge under higher pressure.
> Looking at the sales
> brochure it shows a spark can occur in the plug at
> the bottom,
> this would not bode well if a greenfire type plug
> were used in
> a lean charge...
> 
> Did a compression test, its 150KPa all round, ie Dry
> test, no
> extra table spoon of oil in chamber, 2 valves per
> chamber, engine
> done about 262,000Kms  etc, I think its a bit low
> but each
> chamber is within 5% of the average...Right now the
> car is running
> very smoothly on cruise but have a bit of tappet
> noise when
> accelerating hard at 3,000+ rpm <sigh>
> 
> Comments, anyone know their last compression test on
> a 2-valve ?
> 
> 
> 
> 
> Regards from
> 
> 
> Mike
> Perth, Western Australia
> VL Commodore Fuse Rail that wont warp or melt !
> Twin tyres for most sedans, trikes and motorcycle
> sidecars
> http://niche.iinet.net.au
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> http://lists.diy-efi.org/mailman/listinfo/diy_efi
> 



	
		
__________________________________ 
Yahoo! Mail - PC Magazine Editors' Choice 2005 
http://mail.yahoo.com