Hi Rev Misfire as in past 6k

Post by **Coops** » Fri Aug 29, 2008 12:06 am

Bit of a confusing problem,

on the rollers saturday the car was hitting well over 6-6.5k no probs at all.

didnt abuse car on way hoem and parked it up.
got car out yesterday, took for run, and now when it gets to just over 6k it holds back as if its on a rev limiter,
the limiter was set on 7.5k now set at 9 still does it,

have a new set of plugs and cap, no rotor arm as that was new a while back but may change it,
any ideas what it could be???
up to this missfire the car revs and pulls like a train every time. then plays up when it gets to just over 6k.

Unilite playing? cdi unit? leads? coil?

all advice welcome.

Ian Anderson · Post by **Ian Anderson** » Fri Aug 29, 2008 7:03 am

Bad fuel?
Perhaps a blockage in the pipe / dirty filter

Ian

IanT · Post by **IanT** » Fri Aug 29, 2008 8:33 am

Different plug gaps?

Where did I read somewhere recently about RV8 high rev misfires & plug gaps ??
Found it: http://www.v8forum.co.uk/forum/viewtopi ... +plug+gaps

ian.stewart · Post by **ian.stewart** » Fri Aug 29, 2008 12:28 pm

I had aplug missfire problem, turned out to be the wrong gap, closed the gap to 33tho, and the problem went away

Post by **katanaman** » Fri Aug 29, 2008 4:25 pm

ECU logs should tell you a bit. If it shows the misfire then its the unilite or cdi depending where you take your trigger from. Might even show something in the fuel itself you never know.

Post by **Rossco** » Sun Aug 31, 2008 3:53 pm

I would opt for new plugs.

Doubt if it's the CDi. You've got the 685 and that's a beast of a unit well capable of more than you've given it.

Post by **Coops** » Sun Aug 31, 2008 8:03 pm

Marki,
a log of it is here, you can see the missfire as i held it foot to the floor to try and get a reading on the log while accelerating,

http://www.v8forum.co.uk/zip/newdatalog.zip

Post by **katanaman** » Sun Aug 31, 2008 8:33 pm

yes can see it alright but its raged more than spiked so I wouldn't say its your dizzy or cdi. probably just a plug misfire like others say. Maybe someone else can have a look and see if they agree?

Post by **Coops** » Sun Aug 31, 2008 8:54 pm

i started to fit a new set of plugs and cap before my holiday, so not had chance to test it yet.

Allan, did you get my email before i went on holiday friday regarding some mallory spares mate???

Post by **Rossco** » Sun Aug 31, 2008 9:14 pm

Tony

I'll have a look and see what I have but I'm fairly sure I've only got caps left.

If you want a new one I'll bung it in the post tomorrow.

Post by **Rossco** » Sun Aug 31, 2008 9:20 pm

Rossco wrote:Tony

I'll have a look and see what I have but I'm fairly sure I've only got caps left.

If you want a new one I'll bung it in the post tomorrow.

Also looking at that log I think you've got a slight vacuum leak somewhere.

Post by **Coops** » Sun Aug 31, 2008 9:21 pm

well the plenum is off at the mo as checking the pushrod locking bolts to make sure they are still tight,
will then reseal the plenum,

Post by **Rossco** » Sun Aug 31, 2008 9:25 pm

Do you want a new cap?

Freebie for you of course

Post by **Coops** » Sun Aug 31, 2008 9:48 pm

cheers mate,
that would be spot on

just hoping it's not the rotor arm,
as can't remember who i got my last one from,
may of been you on ebay thinking about it

Post by **Coops** » Thu Sep 04, 2008 9:57 pm

right managed to get hold of another mallory cap today after work,
and a fitted the new plugs,
bolted all back together fired her up, sweet as all ways, took out on the road and ran as normal, until you let rip, as soon as you nail it to the floor and get near 6k the same miss fire is still there,

anything else?
coil?
leads??
dizzy?

starting to loose it with the car