Misfiring and machine gun noise wot high load and boost.
07-12-2009, 01:42 PM
#1
Misfiring and machine gun noise wot high load and boost. I am wondering if it could be anything in my tune that is causing the misfire and machine gun when I got wot then boost kicks in.
I do see one narrow band the passenger one go really lean during the 100 % throttle runs where have the problem so assuming getting misfire on that bank or spark blowout.
The pulsewidths stay the same so figure its not fuel but spark issue.Wideband goes leaner during the incident as well.
But no knock retard during it and as said pulsewidths stay steady.
Here is slight older tune .Will post new one shortly as well. New tune have dialed up timing a lot as my engine is 408 not 346 and was using a 346 map.
Figure the big lower compression 408 can take quite a bit more timing for sure off boost and maybe bit more on boost as well .Its 9.5 to 1 and run 94 octane e10 . No alc or meth injection currently.
I do see one narrow band the passenger one go really lean during the 100 % throttle runs where have the problem so assuming getting misfire on that bank or spark blowout.
The pulsewidths stay the same so figure its not fuel but spark issue.Wideband goes leaner during the incident as well.
But no knock retard during it and as said pulsewidths stay steady.
Here is slight older tune .Will post new one shortly as well. New tune have dialed up timing a lot as my engine is 408 not 346 and was using a 346 map.
Figure the big lower compression 408 can take quite a bit more timing for sure off boost and maybe bit more on boost as well .Its 9.5 to 1 and run 94 octane e10 . No alc or meth injection currently.
07-19-2009, 08:04 PM
#3
I figured out problem. Took out 7 /8 plugs ,number 8 is nuts with my nitrous right over it.
Anyway found the problem. My 200 buck granatelli wires were cooked thru.
And they are supposed to take 1200 degrees. Well think the boots are supposed to take 500 and the sleeves 1200. Burnt right thru the sleeves wasn't using stock heat shields.
Number 5 burnt and number 6 burnt. And number one somehow had no spark plug terminal in the boot just a wire! Think the box was maybe a repack but whatever cant' be bothered trying to get warranty on the wires. I put in a combination of stock ones and accel 9000 that had lying around and used the metal boots on the number 5 and 7 for now. Will be using the metal boots on all of them. Going to think msd wires with the metal boots.
Car is running great now can boost to full 8psi current setting no machine gun anymore. Plugs looked good they were tr6ix iridium but put in some autolite 103 since was in there anyway and can use the iridiums in my other NA car. Gapped to .028 and again zero problems. Very happy to finally fix the problem. Never figured it would be brand new wires. Had an acell 9000 burn out also think it was number 6 and didn't use factory metal sleeve figured accell was heat protected enough..wrong!
Anyway found the problem. My 200 buck granatelli wires were cooked thru.
And they are supposed to take 1200 degrees. Well think the boots are supposed to take 500 and the sleeves 1200. Burnt right thru the sleeves wasn't using stock heat shields.
Number 5 burnt and number 6 burnt. And number one somehow had no spark plug terminal in the boot just a wire! Think the box was maybe a repack but whatever cant' be bothered trying to get warranty on the wires. I put in a combination of stock ones and accel 9000 that had lying around and used the metal boots on the number 5 and 7 for now. Will be using the metal boots on all of them. Going to think msd wires with the metal boots.
Car is running great now can boost to full 8psi current setting no machine gun anymore. Plugs looked good they were tr6ix iridium but put in some autolite 103 since was in there anyway and can use the iridiums in my other NA car. Gapped to .028 and again zero problems. Very happy to finally fix the problem. Never figured it would be brand new wires. Had an acell 9000 burn out also think it was number 6 and didn't use factory metal sleeve figured accell was heat protected enough..wrong!
07-20-2009, 10:15 AM
#5
I am running stock coils but only going to 8psi so far but pretty sure will be ok to 15psi or so that is likley going to be top boost with upgraded 70lb/min LG turbos which plan on getting. I have 300 shot potential of spray as well but will likely run 125 or so shot. instant spool and supercooling effects . Nitrous was mostly installed for intimidation factor and for car show factor.It works good for that.
A twin turbo car with direct port nitrous is a pretty big attention getter!
I will likely get the truck setup just making sure it can work with regular msd f body wires otherwise will get longer ones.
So my issues were 100% wires burning thru. you should be fine running pretty much any good plug like tr6,tr7, autolite ,the ngk iridiums at around .25 to .028 gap even on stock ignition but for sure on the truck coils. You can also try dailing up the dwell on hptuners.
A twin turbo car with direct port nitrous is a pretty big attention getter!
I will likely get the truck setup just making sure it can work with regular msd f body wires otherwise will get longer ones.
So my issues were 100% wires burning thru. you should be fine running pretty much any good plug like tr6,tr7, autolite ,the ngk iridiums at around .25 to .028 gap even on stock ignition but for sure on the truck coils. You can also try dailing up the dwell on hptuners.
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07-20-2009, 12:49 PM
#8
Check your wires..maybe a burnt one...are wires newer?
High mileage car..maybe weak coil or coils.
I would go to the truck coils pretty much plug and play. Just trying to find out for sure
if f body msd wires fit with them since the coils sit higher up on the valve cover. Hope they clear my direct port lines as well.
High mileage car..maybe weak coil or coils.
I would go to the truck coils pretty much plug and play. Just trying to find out for sure
if f body msd wires fit with them since the coils sit higher up on the valve cover. Hope they clear my direct port lines as well.
07-27-2009, 09:58 AM
#9
orderd some msd wires but now hearing they don't fit the truck coils.Conflicting opinions on that . Also want to use metal boots.
I seem to have a misfire problem again with my car. I should maybe just use factory wires in the metal boots like one guy is with same turbo kit and says he has no problems. But other guys are using the msd with no metal boot covers and they also said no problem.
Still would like to go to the truck coils at some point.
I seem to have a misfire problem again with my car. I should maybe just use factory wires in the metal boots like one guy is with same turbo kit and says he has no problems. But other guys are using the msd with no metal boot covers and they also said no problem.
Still would like to go to the truck coils at some point.
07-27-2009, 02:11 PM
#10
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orderd some msd wires but now hearing they don't fit the truck coils.Conflicting opinions on that . Also want to use metal boots.
I seem to have a misfire problem again with my car. I should maybe just use factory wires in the metal boots like one guy is with same turbo kit and says he has no problems. But other guys are using the msd with no metal boot covers and they also said no problem.
Still would like to go to the truck coils at some point.
I seem to have a misfire problem again with my car. I should maybe just use factory wires in the metal boots like one guy is with same turbo kit and says he has no problems. But other guys are using the msd with no metal boot covers and they also said no problem.
Still would like to go to the truck coils at some point.
Last edited by SuperC1; 07-27-2009 at 03:07 PM.
07-28-2009, 07:58 AM
#11
Might this The MSD truck wires look the same as the car wires but they are a little bit longer. I pulled all my wires and tested them, and found two of them were bad. I haven't taken the car back out, but I will tonight. I couldn't find any test data for the coils so I couldn't test them I think Gm is keeping that info a secret.
Has some tech info on the various coils....
http://www.megamanual.com/seq/coils.htm
07-28-2009, 08:55 AM
#12
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This is what I found for the MSD coils.
Primary resistance, .57 ohms.
Secondary resistance, 3.1k ohms.
Maximum voltage, 44,000 volts.
MSD 8247 Multiple Spark Coils for LS2/LS7Last Updated: 2009-06-26 11:15:57
