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hi guys,

have a problem i am hoping someone can help me with.

the car will stutter ie. revs will stop building just for an instant on full throttle over about 5500rpm all the way to redline. feels like something is momentarily pulling the car back then releasing then pulling back again and again. the problem seems to be worse the colder the surrounding temperatures are for example at night. on a hot day the car will actually rev fine all the way to redline.

the problem isnt AFM, have alredy tried changing them over. car has been rebuilt and run in just recently. it also has new spark plugs and all that jazz. rebuild uses mostly stock items except for a slight overbore requiring larger pistons (larry perkins racing series). also computer has been reset twice now.

any help would be greatly appreciated

thanks

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forgot to add the car has had a diagnostic done and nothing came up.

incorrect spark plug gap was my first guess too. i dont know what they are gapped to as a workshop did this. i thought they might be too wide but the guys there assured me that wasnt the case.

keep those ideas comin

thanks

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last night i got as far as swapping igniter packs found one of the plugs was very loose however 2day the stutter is back.

when it stutters there is a loud pop from the exhaust. would coil packs produce this? also i thought that if the coil packs were playin up it would affect the car when driving normally not just when at high revs?

anyway if sum1 could clear that up 4 me that would be great

thanks again

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last night i got as far as swapping igniter packs found one of the plugs was very loose however 2day the stutter is back.

when it stutters there is a loud pop from the exhaust. would coil packs produce this? also i thought that if the coil packs were playin up it would affect the car when driving normally not just when at high revs?

anyway if sum1 could clear that up 4 me that would be great

thanks again

The pop is most likely backfiring (ignition of the unburnt fuel in exhaust pipe) from ignition failure in one or more cylinders.

My guess is also on coil packs not providing enough voltage (resistance across the plug gap is greatest under peak load). Try borrowing a good coil for someone and substituting one at a time.

Could also be a cracked insulator on a spark plug or cracked plugs on the coil pack harness. Also check that the harness ground lug is clean, connected properly and grounded tightly.

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hi guys,

it doesnt seem to be my coil packs. swapped them with a freinds ran his in mine and mine in his gtr and both cars ran fine.

a new problem is developing now which i guess is caused by this miss or ignition failure. when idleing the car will suddenly drop revs and sound like it is under heavy labour. when it does this there is heaps of smoke coming from the exhaust which i am gussing is unburnt fuel.

hardest thing is the car wont play up all the time so it is very hard to get my mechanic to look at it.

again any help would be great

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ive got almost exactly the same problem with my suzuki.normal boost is fine.if the car is around85 degrees or higher is fine on high boost but if the temp drops lower on full boost it has a stutter.taking the car to the mechanic this arvo so ill see what he says is wrong with it and let you know

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