probably because the majority of general servicing mechanics don't really understand what different issues cause missfires..

cause all they do 90% of the time is general servicing, and problem resolution and fault finding goes to the guys who've been doing the bizz for twenty million years..

and you'll also find guys who mods cars will generally have a better idea right away than the true soobapoo mechaniks as they've probably had the same problem..

anyway, for my take on it, could be the following, plugs, either you've melted one, or its got too big a gap, and spark is blwoing out, its got a semi melty piston and theres oil getting in there causing a missfire, fuel pump is bung or on its way out, leads, if it has them, or a dodge coil or coil pack, and beyond that, a wiring fault somewhere, or faulty cam angle sensor or afm..

should give you a bit of stuff to try out..

id go for the leads and plugs first off tho, also have a good look at the colour of the plug, if its too clean/grey/white it could be running lean which will also cause a miss fire, and in the end, lead to detonation and busted bearings, smashed ring lands, or pistons with holes in them...

and a real long shot, could be a stuffed injector pouring way to much fuel into the thing for it to handle and its wetting the plug tip causing it to miss too..

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Jesus Built my car, Its a love affair, Mainly Jesus and my hotrod

i did ask i was just getting some extra feedback, it can't hurt to get a few more opinions from other rex owners... =(

Fitted an Air flow meter element today, fixed it.

old thread but my gc8 00 is getting occasional missfire on WOT. Now before my 100,000 it was doing this, and i replaced my pfr6bs with pfr7bs. This solved the problem as im running 1.2bar. Since the 100,000 pfr6bs were put back in and the 7bs given to back to me. Its happening again, so i am going to replace them. What i want to know is, the leads that go to the plugs, how often should they be changed?

I noticed in my service manual they are not required to be changed at 50,000 or 100,000 intervals. Whats the deal with that? Dont the leads from the coilpack to plugs ever wear down? Surely they would, and if so what are some nice leads to purchase, maybe ross can help me out

Thanks in advance,

Eric.

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Honda Hannspree Edition CBR 600 RR - SOLD
Yamaha FZ1N - Purchased

Like all things, they degrade over time. It is not unusual to have to change the leads within 2 years/40k on some cars. It's usually best to have a good look at them and if you can see any wear marks, dark spots or grey/arc spots, then change them. It is good practice to replace all of them and eliminate the hassle of any others failing. As far as what brand, well genuine leads are actually a decent quality and they fit properly. You can try some other leads but you will not get any more power out of them and they will still only last about the same as factory ones... 2c worth.

Hate the miss under WOT, it's so offputting and you have to back off big time. I reckon the leads would be the least chance of being the culprit Eric, especially if they are kinda newish .. year or so.

I know everyone says it, and i have been with you before when your car has done this a long time ago, and it was your Pod filter and AFM yeah?

You don't run a Brant, so you can rule that out.

- Plugs (gapped correctly, recommend NKG Platinums)
- AFM
- Coilpack

Intermittant issues are so much fun aren't they.

On a side note, does anyone know when the Brant kicks in for Anti Hijack, and it kills the motor, is that killing ignition or fuel?

R.

Rich,

I know what the problem is with the miss firing under WOT, its the plugs. Because im running a high boost in require NGK pfr7b's not the 6b's. Just wondering when/if i should change my leads, they have not been changed since ive had it at 67,000. its got 102,000 on it atm.

When i back off and then accelerate, my car always had a slight stutter to begin with. From what ive been told its the PowerFC and z32 AFM on my 2ltr engine.

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Honda Hannspree Edition CBR 600 RR - SOLD
Yamaha FZ1N - Purchased

Seems weird being the plugs ..

I have ran both platinums and iridiums @ 20psi with the correct gapping and they have been fine with my EJ205. Unsure of what those part numbers you are quoting mean sorry ..

Sean seems to think the Platinums are the go, had no issues with either plugs on my motor. Just saying keep an open mind with your problem and don't get set on the solution until you are 100% sure as in a lot of cases you'll change the plugs back to the ones you think should work and the problem remains ..

Intermittant issues dude .. they'll do your head in.

Yeah, i know. All the numbers and letters are, are the codes to different types of NGK plugs. 6b's are used for less boost where as 7bs are used for higher boost. Both are platinum types, which leads me to believe 6b and 7bs are gapped differently, which creates this problem. In the meantime ive given 'chitty subaru' a call to see what the price of some genuine leads are. Hours later, might i add, nothing as of yet lol.

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Honda Hannspree Edition CBR 600 RR - SOLD
Yamaha FZ1N - Purchased

I believe my car has a miss firing problem as well. Its not the AFM because I just stuck a new one in there and also have tried another AFM from another car.

When idles, I see the engine has a real light shudder/shake in intervals. You can sorta pick it out if u listen to it carefully. Plugs were changed at 100k service - How often should these be replaced? Spark plug leads I believe they are factory - Unsure if it has been changed.

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STi Version VI