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Misfire

Started by _Kevhaze_ , Mar 07 2016 04:04 PM

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13 replies to this topic

#1 _Kevhaze_

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Posted 07 March 2016 - 04:04 PM

Hi Everyone,

I just recently got my torana on the road and I am loving every bit of it except this random misfire while cruising, its got me stumped at the moment without throwing a heap of different parts at it.

Initially I had a surge and misfire while cruising I solved the surge as it was the needle and seat in the secondaries was stuffed (its a new carby but old needle and seat) The old needle and seat was out of my XC as I stole the new needle and seat out of it to fix my XC and I forgot I had swapped them so in the end a new needle and seat and the surge was fixed.

I also had to change my power valve as it was activating way to early and I could use a 1/4 of a tank just going 30km

I tested all my leads and found one to be a bit dodgy with high resistance so I replaced it with a new one. The rest were all new and there's a long story to the reason why I had one old one on there. That still didn't fix my problem so I took the spark plugs out of my HQ Pano as I knew they were good and put them in still with no luck also fix the problem. I don't seem to notice the misfire when cold but only once it gets some heat into it. One thing I have noticed is that my fuel filter (Positioned between the carby and fuel pump) will start off full when cold but once the engine bay is hot it would be lucky if its a 1/4 full, could it be fuel vaporisation?

it still seems to be a bit thirsty though I reckon.

ok now car specs

308 red

4sp m21

2.78 lsd

Holley 600 vac sec

blaster 2 coil

MSD 6al

I know I will cop it for this bit a Pro Comp mag pickup Dist ( it was all I could get at the time but as soon as I get the pennies it will be upgraded to a msd unit from rocket ind)

If there's anything else anyone wants to know just ask and If I remember something else I will post it up.

Cheers Kev

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#2 Rockoz

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Name:Rob
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Posted 07 March 2016 - 06:26 PM

Fuel filter sounds normal.

Would think more again on leads.

Could be a bit of crossfire.

Wait until it is nice and dark and kick her in the guts and have a good look at the leads.

COuld also be tracking in the dissy cap.

These are the first things I would do to check it out.

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#3 Oversteer

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Car:LH SLR5000
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Posted 07 March 2016 - 07:00 PM

Does it mis on power ?

a lot of the time cruise misfire is fuel issue !

.... have seen pick-up come loose in pro-comp dizzy....screws holding it down in the alloy were stripped brand new !

Edited by Oversteer, 07 March 2016 - 07:01 PM.

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#4 _Kevhaze_

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Posted 07 March 2016 - 07:04 PM

Oh and I forgot to add once it cools down again the fuel filter is full plus I just sprayed some flammable liquid around the manifold and carby to check for vac leaks but was all good

Cheers Kev

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#5 _Kevhaze_

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Posted 07 March 2016 - 07:08 PM

Hi Guys I will fire it up shortly as it has gotten dark enough now, I couldn't see any signs of tracking when I did all my earlier changes but no harm in looking again.
I have given it a boot full out the road and I couldn't notice the miss

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#6 _Kevhaze_

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Posted 07 March 2016 - 07:30 PM

Ok well I just fired it up with all the lights off and I couldn't see any flashes and I also checked the dish there is no signs of tracking and all the componets are tight

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#7 Rockoz

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Name:Rob
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Posted 07 March 2016 - 07:55 PM

Found years ago that some leads will test okay, but break down under load.

The bad connection gets worse with heat and more noticeable at revs is the theory.

Could be loose pickup.

Could be slightly bent dissy shaft.

Could be lots of things actually.

Just take note of what is happening whenever it decides to miss and work it out possibly from that info.

Can be a pain to find sometimes

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#8 _Kevhaze_

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Posted 07 March 2016 - 08:10 PM

Yep she is gonna be a fun one to figure out, I am a little worried that it is the leads as they are the ones you cut to length and make yourself which there is a chance one or two might not be quite right

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#9 _Kevhaze_

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Posted 08 March 2016 - 05:04 PM

Well I took it for another little drive after playing with a couple of things and driving down a smooth road this time I can feel it missing randomly cold or hot but not under heavy acceleration. As soon as I get some more pennies I will get a new set of leads for it.

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#10 Oversteer

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Car:LH SLR5000
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Posted 08 March 2016 - 05:55 PM

What do the plugs look like ?

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#11 _Kevhaze_

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Posted 08 March 2016 - 06:20 PM

The pic I have up loaded is one of the plugs from the original set when it was running the wrong power valve, the excess oil on the thread is from my rocker cover gasket which was weeping but now fixed

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#12 _mello92_

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Posted 08 March 2016 - 07:59 PM

Do you have vacuum advance? If so, blank off and test drive.

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#13 _Kevhaze_

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Posted 08 March 2016 - 08:35 PM

Nah no vac advance on it only mechanical

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#14 _Kevhaze_

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Posted 24 March 2016 - 11:23 AM

Hey Guys,

Well I have finally had a chance to fiddle with it and I have had luck. I cleaned all the connections in in the dizzy and to it, replaced my leads and took it for a run I found it improved it and it was better but still not right so I stole my dad's timing light and changed it from 6deg to 10deg and took it for another run and it was great, I also checked the total timing and made another slight tweak.
I took it for a nice cruise yesterday from Kyabram to tongala to echuca and back to ky, it didn't miss a beat.

Thanks everyone for all the help it has been greatly appreciated.

Cheers Kev