Forced Induction - what gap and spark plugs?

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Originally Posted by Lukezen27

thats excatly what happens




Why did it just start now?

I've been hitting it far harder for longer then that 1/4 mile time

I'm think'n the 8 pound spring has loosened up a bit and letting a bit more boost then my last dyno

It was brand new last time I got her dynoed

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Have you read any of the posts? Its all been explained. Your missfireing/blowing out the spark. Stop thinking, goto repco and ask for 4xBKR7E-11's.. Hand over $16.90. Tap them agains the wall until your 0.8mm feeler gauge is dragging on the electrode. Install. Test. Problem fixed.

Do you even know what boost cut is? It cuts ignition signal. Which is exactly what happens when your spark is being blown out by boost. You have the wrong plugs. You have the wrong gap. Simple. DO it befor eyou blow out ur headgasket again cause of the miss-firing.

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Originally Posted by aaronng

Oops, just reread and he has a tune for his setup. As long as his tune adds more fuel in as the RPMs increase irrespective of what the map sensor reads after maxing out, he's fine.

But there are those who still run stock tune.

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His tuned for 10-11psi. I assume toda has fattened up the topend for some safety. Regardless, the emanage does not care what boost u are running. It will happily let you run right off the maps and detonate your head off. It doesnt care.

#Unless the boost cut limiter has been enabled and set. But im sure if it was, toda would of mentioned something in this thread.

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Originally Posted by Weq

His tuned for 10-11psi. I assume toda has fattened up the topend for some safety. Regardless, the emanage does not care what boost u are running. It will happily let you run right off the maps and detonate your head off. It doesnt care.

#Unless the boost cut limiter has been enabled and set. But im sure if it was, toda would of mentioned something in this thread.

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Yeah Adrain has tuned my car with these plugs and gap and yes more fuel than needed for safety..

Nope I don't think he setup the boost cut limiter that I know of.

But I get the cooler plugs and gap em won't I need a return?

Weq, if it were the plugs misfireing/blowing out, the motor will start to hessitate, it all would not suddenly cut out. As I have explained and Lukezen has, its is all suddenly cutting out for a second or so and then is fine again. I have seen it before.

there must be some sort of boost cut inplace, or its overboosting and shutting off, as there must be a certain boost map that it wont read past......

as deano said...........

ask your tuner and see what parameters he has set on the boost readings

Would there be any chance that the boost cut was wired to the output of the knock sensor?

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Originally Posted by Weq

Once a stock map sensor reads over 10.8psi, it does nothing more then stop increasing its voltage. It hits the roof.

The emanage hasnt got a boost cut set, i'll bet my two left testis on it. Toda, care to input?

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Yup, bang on... :thumbsup: (Your balls are safe)

In addition to there being no boost cut function in the E-Manage,
There is a MAP sensor output clamp function.
On boosted applications this clamp voltage is applied on boost so the std ECU does not see boost & fail in to stupidity.

Re Luke's plugs,
To be honest I can't remember the heat range these were.
Probably 6's (BKR6E-11's)
It didn't have an issue on the dyno,
But that said, the drag strip is a different monster & too hot a plug could cause the sensation of a miss fire through pre-ignition (detonation)

That in mind, rather than point the finger at just the plugs.
My guess is the mixtures on boost when subjected to the conditions of drag racing may well be a little too (Safety tune) rich for the boost being run.
That is wavering between 11.1 & 11.5 @ the tail pipe which is closer to 10.7 & 11.1 at the engine.
Combine this with the rapid drop in ignition timing on boost & it's not a big stretch to consider the missfire is possibly a rich missfire.
We could try leaner, but I also don't have any wish to break it.
Anyway, we'll all probably find out when Luke gets back from Holidays...
That's my 5 cents
Cheers

When you say misfire, do you mean the spark is not strong enough to ignite the entire mixture? Or is the resistance to spark from electrode to ground is too great because of the rich mixture and high pressure, so he gets a spark that is inadequate to start combustion?

hey luke just get some copper plugs, just in case you kill another set.

Well there apears that e-manage has the boost cut enables but I didn't do it.. and Adrian didn't coze he didn't know it was there, must be stock setting

I saved the SGC file today at work to check it out..

http://www.doubledynasystems.com/Car/dyno/boost_cut.png

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Originally Posted by Lukezen27

Well there apears that e-manage has the boost cut enables but I didn't do it.. and Adrian didn't coze he didn't know it was there, must be stock setting

I saved the SGC file today at work to check it out..

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LOL...
It's not a boost cut as such,
It is to stop the std ECU going bananas when it sees boost pressure.
(Remember your car used to throw a check light)
Anyway,
As I said above:
There is a MAP sensor output clamp function.
On boosted applications this clamp voltage is applied on boost so the std ECU does not see boost & fail in to stupidity.

& what you're looking at there is that exact clamp setting I was talking about.

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Originally Posted by TODA AU

LOL...
It's not a boost cut as such,
It is to stop the std ECU going bananas when it sees boost pressure.
(Remember your car used to throw a check light)
Anyway,
As I said above:
There is a MAP sensor output clamp function.
On boosted applications this clamp voltage is applied on boost so the std ECU does not see boost & fail in to stupidity.

& what you're looking at there is that exact clamp setting I was talking about.

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I see

I thought as much and did both factions

And your sure it won't be the stock map sensor then?

So I should just get some BRK7E(-11) gap em to 0.032?

I've got the new Walbro fuel pump next to me and will install that tomorrow to cross that off the list lol