high boost top end miss?
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single digit dreamer
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From: omaha ne
high boost top end miss? i am geting a significant top end miss when i turn up the boost. somewhere between 18psi and 22psi it will kick in depending on the weather. on a good weather day it will kick in sooner. on a hot day later.
while on drag week i only had tr6 plugs so i haven't tried a cooler plug but i did gap a set of tr6's down to .025 and that didn't change the condition at all. i will be trying a cooler plug and they come set at around .025 out of the box. i expect the same problem with the cooler plug. i have also tried a/f ratios from high 11's down into the 10's with no effect.
Kurt from W2W sugested i ramp up the ignition dwell to around 6ms up top but edit and efilive do not seem to have this option, i do not have acess to hptuners.
what else should i try? even smaller gap? how much smaller? any other ideas?
i am near the limit of the turbo right now and plan on hiting it with a little nitrous to push me into the 9's but i would like to fix this miss.
while on drag week i only had tr6 plugs so i haven't tried a cooler plug but i did gap a set of tr6's down to .025 and that didn't change the condition at all. i will be trying a cooler plug and they come set at around .025 out of the box. i expect the same problem with the cooler plug. i have also tried a/f ratios from high 11's down into the 10's with no effect.
Kurt from W2W sugested i ramp up the ignition dwell to around 6ms up top but edit and efilive do not seem to have this option, i do not have acess to hptuners.
what else should i try? even smaller gap? how much smaller? any other ideas?
i am near the limit of the turbo right now and plan on hiting it with a little nitrous to push me into the 9's but i would like to fix this miss.
On The Tree
Joined: Aug 2005
Posts: 155
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From: oklahoma city
How about trying some cooler plugs. The tr6 is only one heat range cooler. http://www.thunderracing.com/catalog...vid=9&pcid=102 They have some 3 and 4 heat ranges colder. Might be an idea.
Thread Starter
single digit dreamer
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From: omaha ne
i have loged the back presure in the cross over pipe before. i was seeing about a 3-1 ratio but that was with a t76 and 3" dp. i haven't loged back presure with the pt88 and 4"dp.
my boost holds steady at this level. on the dyno when i cranked it all the way up i would see 26psi and it would settle down to 22psi, i haven't tried to turn it up much past 21psi at the track yet.
is there something worth learning that would make it worth my time to log the exhaust presure?
my boost holds steady at this level. on the dyno when i cranked it all the way up i would see 26psi and it would settle down to 22psi, i haven't tried to turn it up much past 21psi at the track yet.
is there something worth learning that would make it worth my time to log the exhaust presure?
TECH Apprentice
Joined: Jul 2005
Posts: 354
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From: Wilton Ca. (Sacramento)
I'm using the BR7EF's on mine at up to 22 psi. The Lightning guys often go these plugs once they exceed the TR6's and I've had no problems at all with misfire at a .032" gap and 22 psi. They are a step colder than the TR6's.
I have had issues with too big of an alky nozzle, but didn't really misfire, just flat shut the spark off.
Jody
I have had issues with too big of an alky nozzle, but didn't really misfire, just flat shut the spark off.
Jody
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single digit dreamer
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From: omaha ne
i just ordered 3 sets of plugs to try.
br7ef
ar94
ar93
i tried the br7ef plugs once and they had a prety strong miss at idle. i might just throw in the ar93's and make a glory run(20psi and a 100+shot), let the parts land where they may or get a nice solid 9sec run
. they dont have any of these plugs just laying around in town so i am going to load up and try a few diferent set up's. i have seen a a couple of posts where people say the autolight ar93 will not missfire at idle as easy or foul as easy as you would think for a plug that is 3 ranges colder. the reason i am running the 6's still is because of the way the 7's ran like *** just putting around. maybe the ar's are the trick?
br7ef
ar94
ar93
i tried the br7ef plugs once and they had a prety strong miss at idle. i might just throw in the ar93's and make a glory run(20psi and a 100+shot), let the parts land where they may or get a nice solid 9sec run
. they dont have any of these plugs just laying around in town so i am going to load up and try a few diferent set up's. i have seen a a couple of posts where people say the autolight ar93 will not missfire at idle as easy or foul as easy as you would think for a plug that is 3 ranges colder. the reason i am running the 6's still is because of the way the 7's ran like *** just putting around. maybe the ar's are the trick? TECH Apprentice
Joined: Jul 2005
Posts: 354
Likes: 0
From: Wilton Ca. (Sacramento)
Originally Posted by parish8
i just ordered 3 sets of plugs to try.
br7ef
ar94
ar93
i tried the br7ef plugs once and they had a prety strong miss at idle. i might just throw in the ar93's and make a glory run(20psi and a 100+shot), let the parts land where they may or get a nice solid 9sec run. they dont have any of these plugs just laying around in town so i am going to load up and try a few diferent set up's. i have seen a a couple of posts where people say the autolight ar93 will not missfire at idle as easy or foul as easy as you would think for a plug that is 3 ranges colder. the reason i am running the 6's still is because of the way the 7's ran like *** just putting around. maybe the ar's are the trick?
br7ef
ar94
ar93
i tried the br7ef plugs once and they had a prety strong miss at idle. i might just throw in the ar93's and make a glory run(20psi and a 100+shot), let the parts land where they may or get a nice solid 9sec run
. they dont have any of these plugs just laying around in town so i am going to load up and try a few diferent set up's. i have seen a a couple of posts where people say the autolight ar93 will not missfire at idle as easy or foul as easy as you would think for a plug that is 3 ranges colder. the reason i am running the 6's still is because of the way the 7's ran like *** just putting around. maybe the ar's are the trick?
Some of the Lightning guys say the same about the idle on the BR7EF's too, but mine idle fine and always have, at least for the last 13K miles I've had the built motor. Don't think it's because of my tuning! 
I think you're on the right track, try a couple different setups. You're beyond where most any of us have been as far as power, but boost and cylinder pressure-wise not that far off.Jody
Thread Starter
single digit dreamer
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From: omaha ne
i have the missfire test shut off. between trying cold plugs and a bigish cam i have enough missfires to set a code and kill my converter lockup.
it is definately more than one or even two cylinders. i think it is probably spark blow out and am just wondering if there are other things i can do to reduce spark blow out other than plugs and gap changes.
it is definately more than one or even two cylinders. i think it is probably spark blow out and am just wondering if there are other things i can do to reduce spark blow out other than plugs and gap changes.
Teching In
Joined: Jun 2005
Posts: 44
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http://www.kennebell.net/accessories...oostaspark.htm
http://www.msdignition.com/2005/2005_2.htm
I have heard of a dirty fuel injector causing a misfire that seemed like a ignition problem.
http://www.msdignition.com/2005/2005_2.htm
I have heard of a dirty fuel injector causing a misfire that seemed like a ignition problem.
Thread Starter
single digit dreamer
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From: omaha ne
Originally Posted by Pro Stock John
Magnus (Keith@HPTuners.com) said you can change the dwell time of the coils with their software.
Will the megasquirt do the job on the ignition side with cylinder pressures that are that high? As far as I know the only engine managment besids the stock pcm that can do it is the bs3, other aftermarket stand alones are having a hard time with spark beyond were you are at now.
Thread Starter
single digit dreamer
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From: omaha ne
there are a couple of ways to do it. i think mega can run the stock coils but in a wasted spark set up and i think you can set the dwell with mega too. there are other ways to make it work too but i dont know how well they work at these cylinder presures.