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H25A V6 with a mis-fire
Posted: Wed Nov 11, 2009 11:16 am
by Weemsy
got a Grand vitara with a H25A motor.
problem is that it has a mis-fire on cylinder 4. ive swapped plug, coil, lead, injector to different cylinder, but the miss stays on cylinder 4. compression test and leak down test were spot on.
the only thing ive noticed is the plug is black, compared to other cylinders, but, still has a spark.
any help please????
cheers
weemsy
Re: H25A V6 with a mis-fire
Posted: Wed Nov 11, 2009 11:40 am
by Bolo
Weemsy wrote:got a Grand vitara with a H25A motor.
problem is that it has a mis-fire on cylinder 4. ive swapped plug, coil, lead, injector to different cylinder, but the miss stays on cylinder 4. compression test and leak down test were spot on.
the only thing ive noticed is the plug is black, compared to other cylinders, but, still has a spark.
any help please????
cheers
weemsy
test the voltage going to the spark plug. as it may be enough to jump the gap but not enough for it to burn all of the fuel ...
Re: H25A V6 with a mis-fire
Posted: Wed Nov 11, 2009 11:46 am
by Bolo
you also said you swapped the injector. have you seen the injector squirt fuel??? it could not be getting a pulse to work on number 4
Re: H25A V6 with a mis-fire
Posted: Thu Nov 12, 2009 1:05 pm
by Weemsy
gidday bolo,
yeah ive scoped the injectors and the coils, both have a matching pattern to other cylinders. (although that doesnt mean the firing point is correct).
just had the induction manifold off just incase the gasket was split (clutching at straws
)but all appears fine.
Re: H25A V6 with a mis-fire
Posted: Thu Nov 12, 2009 1:27 pm
by Bolo
well another thing i would try is , find a mate or someone you knwo if they have one , and swap computers and see what that does.. it could be a fault in there.
Re: H25A V6 with a mis-fire
Posted: Thu Nov 12, 2009 3:04 pm
by Weemsy
gidday bolo,
apparently they cant be swapped, as its a coded ecu for the immobiliser in the key
aint technology great!!!!
Re: H25A V6 with a mis-fire
Posted: Thu Nov 12, 2009 3:16 pm
by Bolo
Weemsy wrote:gidday bolo,
apparently they cant be swapped, as its a coded ecu for the immobiliser in the key
aint technology great!!!!
well see if you can get it on a scan tool and see if any fault codes come up. and go from there..
Re: H25A V6 with a mis-fire
Posted: Thu Nov 12, 2009 9:48 pm
by flyingbrick
black spark plug means its running rich- probably so rich it wont fire nicely.
probably injector stuck open which would not show on scope as electrical pulse sent to injector would remain the same.
Guessing as im not a technician.......