Misfire

[BobWrinkle]

Hey guys what are the possibilities for misfiring?

I can hear it missing every 5secs on idle and sometimes i get crazy misfires on boost.

I have changes leads and now running bosch super 4s however they are gapped to 11 as per both ngk and bosch books...

Ideas?

 

[Pyro]

Faulty coil packs??

 

[matress]

i think the ngk book states the gap that the plugs come with...

you should gap them to about 0.7mm

that could be one reason why they're missing.

what heat range are they?

 

[BobWrinkle]

Both books has 90-92 hh galant br4 turbos as running 11mm gaps.

Have FR 78 X bosch super 4s in now. And have a set of BP611s in glove box ready to try...

Is there a way to test coil packs?

 

[matress]

11mm is massive man... you can't gap a plug that far... it's probably 1.1mm

but anyway... mitsubishi recommends 0.7-0.8mm gap... it should be stamped on the underside of your bonnet, unless its in japanese

 

[Entaran]

I'm so not telling you this ever again.

THE FACTORY SERVICE MANUAL (please note the caps) SPECIFIES THE SPARK PLUG GAP TO BE BETWEEN 0.7 AND 0.8 MM

Any other stupid questions that i've already answered on MSN and in two other threads?

 

[rob323]

Did the misfire start occuring out of the blue, or did you change something and thats when it started.

I have never had any good experiences with Bosch plugs and now will only use Denso or NGK.
Just get some NGK BPR7ES plugs, gap them to 0.7 mm and see if that $12-$16 investment fixes the problem.

 

[matress]

or even the 6's...

you might have a bit of a problem with 7's fouling, see how you go though.

 

[CLuTZ]

Just get some NGK BPR7ES plugs, gap them to 0.7 mm and see if that $12-$16 investment fixes the problem.

What he said!!

 

[BobWrinkle]

Hmm just noticed on boost a really loud hissing...If i had a boost leak would that be consistent with misfiring?

 

[CLuTZ]

Hmm just noticed on boost a really loud hissing...If i had a boost leak would that be consistent with misfiring?

yes.


dont forget to check your b.o.v too.

 

[bazeng]

WHAT THOSE GUYS SAID!!!

7mm - 8mm

the books are wrong!!

get the plugs without the 11 at the end... they will be pregapped to .8mm

go for 7's if ur driving the thing hard...
6's if its a stocky

 

[BobWrinkle]

Its stock but i drive like a wanker...so 6s or 7s?

 

[bazeng]

7s wont hurt
if it fouls
go back down to 6's

 

[matress]

it'll depend a bit on your tune as to whether they foul or not.

my 7's foul is i leave the car idling when its cold, otherwise it's sweet.

but seriously man, they're about $2.50 each! :lol:

 

[BobWrinkle]

Yeah but I am a busy man and the shitty car shops in the ACT are only ever open during business hours.

 

[smokes]

do you have a boost gauge? i didnt, and my car started misfiring, then i put one on and discovered that i was getting a boost spike, which caused it to miss. obviously though a boost spike wouldnt cause the miss at idle though

 

[BobWrinkle]

Just found the problem.

Massive tear in the ic hose over the exhaust manifold.

Taped up until tomorrow and hooray i had forgotten how much faster it was on full boost