Timing gun erratic signal

EDIS and Megajolt installation related topics. Be sure to review the <a href="http://www.autosportlabs.net/MJLJ_V4_vehicle_installation_guide">Vehicle installation guide</a>

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andyk5000
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Joined: Tue Aug 07, 2012 7:21 am
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Timing gun erratic signal

Post by andyk5000 »

Hi all,
I've got a problem or 2 with my Megajolt system...
I get 3 out of 4 leads to give good pulses with an inductive timing gun,one is weaker,but when the rpm goes above 2000 3 out of 4 drop out completely.
I also have a misfire condition at 2500 rpm and above,and on idle pulling leads 1 and 4 make little difference to the engine's running,although I then get a better spark signal on the gun.
It appears that the timing stutters about at the higher rpm but hard to be certain as the signal gets lost.
This is constant with or without MJ so rules MJ out.
I have tried 2 EDIS units and 2 coils.
Using resistor plugs,silicone 10mm leads, have tried with another lead set,same thing.
Timing wheel has no runout,sensor gap 0.5 mm,have tried increasing it with no change.

Engine is Fiat 1100 FIRE,using one choke of 45 webber on a 750 Formula race car.
When racing its has misfire above 2500RPM,worsening with increased RPM,won't rev above 6000.
The system ran well once,at the rolling road,but never since.

Any ideas anyone??
Thanks,
Andy

andyk5000
Posts: 3
Joined: Tue Aug 07, 2012 7:21 am
Location: United Kingdom
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Improvement

Post by andyk5000 »

Well I've played around some more...
Another EDIS unit,and now the timing gun works over the rev range.
Also the timing seems solid now,can't test for an under-load misfire as yet but hoping I'm on the road to recovery.
Still can't figure out how it could have timing scatter only on cyl 1 though...

brentp
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Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

thanks for the update. let us know how the drive test goes.

Are you using the same timing gun across all of your tests?
Brent Picasso
CEO and Founder, Autosport Labs
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andyk5000
Posts: 3
Joined: Tue Aug 07, 2012 7:21 am
Location: United Kingdom
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Post by andyk5000 »

Hi brent,yes the same gun on all tests.I don't think the problem ever lay with the MJ itself,just everything else.We have a race at Snetterton next sunday so I guess we will find ou then-no chance of a rolling road session before then sadly.I will report back...

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