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Discussion Starter #1
Hey guys, currently running 20Ts at 8psi while I build the fuel table and NGK BKR7 spark plugs. With the oem ECU during engine break in and plugs gapped to 34, I was getting spark blow out right around 4000rpm. Regapping those to .028 got rid of the issue all together.

now with the AEM EMS and larger fuel injectors (1200cc high z) I seem to be getting spark blow out gapped to . 028 at 6000rpm boost seems to creep up to 11psi with the cold weather we’ve had up here in NJ even on an 8lb spring. Anyway, how low do you guys gap the copper ngk plugs?
Then plan is to go with a coil on plug set up over the winter and hopefully be done with it
 

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I wouldn't expect blow out at that low of boost... I'd be wondering about ignition system integrity. How close is the AFR at this point?


I'd have no problem running the gap down into the low 20s if you have to. An ignition amplifier can be a big help also. (but redundant if you're swapping to COP. I'd also take a look at your coil dwell tables and make sure they aren't too low.
 

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Discussion Starter #3
I wouldn't expect blow out at that low of boost... I'd be wondering about ignition system integrity. How close is the AFR at this point?


I'd have no problem running the gap down into the low 20s if you have to. An ignition amplifier can be a big help also. (but redundant if you're swapping to COP. I'd also take a look at your coil dwell tables and make sure they aren't too low.
Be patient with me as I'm still learning.

AFR target in that range is 12.8 with actual AFR landing at 13.3 and it seems the o2 fb is adding 5% of fuel to keep in there. Still doing some driving and fine tuning it before turning o2 fb off.

My coil dwell in that moment is 1.67ms (6000rpm, 11.5psi boost). I've attached a screen shot of my dwell tables and logs in the moment where it starts to break up. again, i appreciate your patience

Paul
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Maybe not apples to apples but thought id share my spark plug gap experience: Spark Plugs and Plug Gap for E-85 and E-85/pump blends...

Note, i have stock coils with potentially over 300,000 miles on them (not replaced in last 120k miles by me, have not seen replacement in service history). PTU has been replaced and is a autozone unit. Ignition system is stock as is ECU (running SAFC2).
 

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Make sure that your voltage is not falling off however and wherever you want to measure that. Least expensive upgrade is "hotwiring" the coils, but that should not be necessary at that level.

Also, the "base cal" from AEM has pretty crappy dwell tables, IMO haha.

-sent from my Galaxy Note 9
 

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Discussion Starter #6
Make sure that your voltage is not falling off however and wherever you want to measure that. Least expensive upgrade is "hotwiring" the coils, but that should not be necessary at that level.

Also, the "base cal" from AEM has pretty crappy dwell tables, IMO haha.

-sent from my Galaxy Note 9
Yea. It’s 100% ignition related. Can you by chance share your dwell table with me? Just for some reference
 

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I had issues as soon as I raised the boost above 10psi 15 years ago. Stock ECU & iridium plugs, but gapping to .026" and doing ground-wires has allowed me to go ~5 years between re-gapping each time at 14-15psi.

Sometimes I go lower in the rear since it's a pain to get at compared to the front bank, going into the low .02X" range doesn't seem to make any difference in my car except longer before blowout.
 

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Discussion Starter #9
I had issues as soon as I raised the boost above 10psi 15 years ago. Stock ECU & iridium plugs, but gapping to .026" and doing ground-wires has allowed me to go ~5 years between re-gapping each time at 14-15psi.

Sometimes I go lower in the rear since it's a pain to get at compared to the front bank, going into the low .02X" range doesn't seem to make any difference in my car except longer before blowout.
Hmm. The ground straps are definitely something I should visit sometime. So, I just gapped mine down to .025 and see how she does. Idles much better already.
 

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FOCO to Wyo
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Hmm. The ground straps are definitely something I should visit sometime. So, I just gapped mine down to .025 and see how she does. Idles much better already.
I can't say for sure if the grounding helped, but it was EASY and CHEAP. I figured a little better spark, little more voltage to the fuel pump, and a little better voltage signal from various sensors was good all-round. My alternator puts out ~13.5-14.3v also, might check that too.

I've never had an issue with idle due to blowout, even when I bought my VR4 for a steal due to it having NA plugs and running terribly it made ~4-7psi at sea level before blowout.
 

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Discussion Starter #11
I can't say for sure if the grounding helped, but it was EASY and CHEAP. I figured a little better spark, little more voltage to the fuel pump, and a little better voltage signal from various sensors was good all-round. My alternator puts out ~13.5-14.3v also, might check that too.

I've never had an issue with idle due to blowout, even when I bought my VR4 for a steal due to it having NA plugs and running terribly it made ~4-7psi at sea level before blowout.
Oh sorry if I wasn’t clear. It doesn’t blow out at idle. Just 6000rpm at about 10psi. I just swapped plugs and it just idled better that’s all. I’m hoping that translates to no blow out when I get back on the road
 

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You are going to get a lot of varying opinions, but those plugs should be fine until you work things out and raise the boost level.

I previously pushed the envelope with BKR7E's at 0.030-0.032" at 28psi lol 😅 they quickly wanted out when the gap opened up but looked fine otherwise.

The car that I tuned today has the same plugs at 0.034" and boosts 15psi smoothly with 3SX Enforcers.

Every car is different though...

-sent from my Galaxy Note 9
 

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Discussion Starter #13
You are going to get a lot of varying opinions, but those plugs should be fine until you work things out and raise the boost level.

I previously pushed the envelope with BKR7E's at 0.030-0.032" at 28psi lol 😅 they quickly wanted out when the gap opened up but looked fine otherwise.

The car that I tuned today has the same plugs at 0.034" and boosts 15psi smoothly with 3SX Enforcers.

Every car is different though...

-sent from my Galaxy Note 9
Yea I think it’s my coils showing their age at 25 years. I just threw another set of 7s in there at a smaller gap. It’s about to get cold here in NJ so I will be swapping in a COP set up during the winter and ditching the coils.

do you do remote tuning, Alan?
 

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FOCO to Wyo
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Ahh, that is normal for our old coils at the larger gap but you should see no blowout for quite a while at .025" even with more boost and the cold. I wonder if your new COP setup will fix everything, I didn't even realize that was an option till I saw one of Alan's youtube vids the other day!

Also interested in remote tuning, wanting some 19/20T's finally.
 

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Gotcha. Either route will work - a new, replacement pack or upgrading. Yes, I can and have done so but only on occasion and selectively. Not to speak on his behalf, but there are a few others who offer the same, such as Eric.

-sent from my Galaxy Note 9
 

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Your sparkplugs show that it's running too rich at low load and too lean at high load which indicates the usual fuel pressure problem that happens with a pump that's too big for the FPR, Stock coils and PTU need about 2.5 msec dwell, They can't be over dwelled because the PTU limits the current to a max of about 7A regardless of dwell time.
 

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Discussion Starter #17 (Edited)
Your sparkplugs show that it's running too rich at low load and too lean at high load which indicates the usual fuel pressure problem that happens with a pump that's too big for the FPR, Stock coils and PTU need about 2.5 msec dwell, They can't be over dwelled because the PTU limits the current to a max of about 7A regardless of dwell time.
EDIT: I think you maybe right. I'll richen it up a bit at the high load. But my low load o2 is at 15AFR

In terms of fuel, im running an AEM 340lph fuel pump and an aeromotive FPR set to 43psi base pressure. Injectors are high z 1200cc.

so, I swapped for fresh plugs gapped to the same .028 and the blow outwent away. I think my coils are the problem and gapping down this low just puts a bandaid on the situation.
 

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EDIT: I think you maybe right. I'll richen it up a bit at the high load. But my low load o2 is at 15AFR

In terms of fuel, im running an AEM 340lph fuel pump and an aeromotive FPR set to 43psi base pressure. Injectors are high z 1200cc.

so, I swapped for fresh plugs gapped to the same .028 and the blow outwent away. I think my coils are the problem and gapping down this low just puts a bandaid on the situation.
How old are your plug wires? Did you resistance test them?
 
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