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Discussion Starter · #1 · (Edited)
Spent a few hours on the dyno ironing out an ignition breakup on the new Series 2 AEM...

On the basemap, the car would break up at about 5K RPM (8 psi boost) and at about 4K RPM at 16 psi boost. This is a stock ignition car.

I logged the coil dwell time and found with all the multiplier tables, we were only getting 1.8ms of dwell at these RPMs.

Messed with the battery offset and dwell vs RPM tables to get the dwell up. Still got the breakup. So then, I logged the dwell teeth and found I was hitting another limit found under the dwell options/max dwell setting. I basically had to double this value and whoa la, a smooth, full pull to redline.

So the moral of the story is: try adjusting the dwell in your ECU before replacing every ignition component in the system :)
 

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Al-key-haul
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Cool, care to share your specific values?

This is one of those things that bugged the hell out of me when I really started digging into these boxes. Dwell Max... in teeth. OK, now explain to me what the hell a "tooth" is when you're using a sync strategy that counts rising and falling edges and processes them via a tooth control table! I figured it out, but only by logging.
 

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Discussion Starter · #4 ·
Ha! Yeah, dwell max in teeth was a new one for me too. I had to make myself a little drawing for it to sink in :)

I brought the max dwell to .9 I believe. I brought the battery vs. Dwell values up to 2.8 in the 12 to 14 v ranges. Since aem loves to use multipliers, there is then the dwell vs. Rpm table that I brought the multipliers up at 4k+ rpm to 140 and that seemed to work. Only reving to 6500 on this motor, so I wasnt concerned about the numbers higher in the table.

You could probably set the rpm multiplier values all to 100 at the higher limit of your rpm range and then set the battery table to 3.3 (or other max desired dwell value you choose) if that makes more sense. Either way, you get the same values in the end.
 
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I'm really surprised this doesn't come up more often. Either people band aid this issue with the HKS DLI, are not trying to light off a 11.8:1 E85 Mix, I'm an idiot, or people just don't want to share.

I was running 11.5 to 11.8:1 AFR at 18 PSI and the car would breakup like clock work around 6000 RPM where AEM starts reducing dwell via the dwell vs rpm table. Raising the multiplier there to never dip below 100%, setting the dwell vs battery RPM higher, and raising the dwell max to "1.25" teeth completely eliminated the issue. This is on new stock coils, new stock PTU, NGK 8 series plugs gapped at .025, and stock wires.

I really appreciated this post and another on the forum on this matter, so I wanted to post exactly what settings are working for me:



If you compare these against a stock cal you'll also see I reduced the multiplier at lower rpm to not overwork the coils since I raise the dwell vs battery voltage table. I raise the 11 to 12 volt region as well, which has aided starting.

I'm waiting on a coil hotwire kit from ninja, with that I think my ignition will be pretty bulletproof.

I have been trying to calculate the max dwell duty cycle, but as noted above its hard to understand with the way our sync strategy works. AEM didn't respond when I asked, which is unusual. I mainly looked into a stock rom in ecuflash and I am still well below the dwell I have run in that. I don't think the coils are in any danger with these settings or even 10 to 20% higher. I would lower the multiplier at lower rpm even further if you wanted to go that high though. There is just no need to beat the coils up that hard. You could honestly probably set the dwell vs rpm table to 100% all the way through and not hurt a thing, but I have not tried that.
 
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