How do you tune ignition maps?

[Brodyj]

How do you tune ignition maps?
Do you just tune for max power or what?
What is the trend of the advance as load increases?
What is a good maximum advance?
At what rpm do you run max advance?
Is detonation very obvious?

If you could help me out I would greatly appreciate it.

Joseph Brody

[Brodyj]

How do you tune ignition maps?
Do you just tune for max power or what?
What is the trend of the advance as load increases?
What is a good maximum advance?
At what rpm do you run max advance?
Is detonation very obvious?

If you could help me out I would greatly appreciate it.

Joseph Brody

[B Lewis @ PE Engine Management]

Hey Joseph,

Tuning ignition is best done on the dyno. Typically, the best timing can be determined by holding a constant operating point with the dyno and tuning for the best torque. My experience has been these small 4-bangers should be fully advanced by 5k-7k RPM. Maximum advance again is engine dependent but a good safe starting point would be to keep it under 38 deg BDTDC. Start with that and slowly increase timing until the torque starts to fall off. Back it up a degree from that point and move on to the next point. My experience with Yamahas and Hondas has been that they are reasonably insensitive to detonation in naturally aspirated form. In other words, the torque will generally drop off significantly before any pinging will occur. Just keep your ears open for a "can full of marbles" sound under load. Hope this helps. Keep us posted.

Brian Lewis
Performance Electronics, Ltd.
www.pe-ltd.com (http://www.pe-ltd.com)
"Complete Engine Management Systems for $798"

[murpia]

I second Brian's advice. Spark tuning is definitely best done on a dyno if you can. What Brian describes is 'minimum best torque' (MBT) tuning. i.e. the minimum spark advance required for best engine torque. The only time this won't work is when you are knock limited, more likely at low revs / lean mixture.

Of course ideal spark timing will be somewhat mixture dependent and definitely intake / exhaust system dependent, so an iterative approach may be required as you tune fuel. Make sure you fit the same intake and exhaust on the dyno as your car, and try to supply the engine with ambient temperature air.

Normally spark is relatively insensitive to engine transients, as long as you have your fuel sorted out. If you are going weak on throttle opening you may hear some knock, but the fix will be fuel not spark. Even the cheapest junk yard EGO sensor can help you here. Just fit it with a light that comes on when it reads lean, and go driving on your base map from the dyno. If the light comes on as you accelerate, add acceleration fuel until it doesn't. Easier still with a datalogger and wide-band UEGO but the simplest approach can still work.

Ian

[Brodyj]

Thanks for the help guys. I think I will be able to dial it in from here. Hopefully, my fuel maps will not be all buggered up when I tune advance.


Peace

[B Lewis @ PE Engine Management]

Before you start tuning fuel, set your advance to be around 10 deg at idle and ramp up to about 35 deg at 6000. Then keep it at 35 the rest of the way out. Use that pattern for all of the load lines. Then try to get the fuel table set as close to optimal as possible. Incorrect mixtures will cause more headaches than having less than optimum timing. Once you are happy with the fuel, go back and tweak ignition.

Brian Lewis
Performance Electronics, Ltd.
www.pe-ltd.com (http://www.pe-ltd.com)
"Complete Engine Management Systems for $798"

[Jon Prevost]

You need to run a "safe" spark map and then tune the fuel with a wideband. There really is no other replacement for this invaluable tool. A wideband will safe you a weeks worth of headaches. If you don't have a wideband, get a job for a week and sum up $300 and get an Inovative Tech. wideband. The hours you spend earning the money to afford the wideband will easily replace the hours of tuning without.
Once you've gotten the vol eff mapped, go back and adjust spark BUT watch the wideband. Adjust the fuel and switch back and forth adjusting each until peak torque. Also, don't bother with trying to run lean best torque on the dyno. I can assure you that you will want to run slightly richer in the car so you migh as well tune for a high 12 low 13 AFR instead of the "13.8". You can try but I'll bet the car will respond better slightly rich.
Hint for free: Don't run max timing, run the least possible making the same torque. This shouldn't affect your output. If you have the ability to input vehicle speed into your spark control do so and have a couple degrees removed at higher speeds to make certain you don't detonate.

, Jon
"Success - it 's what
you do with what you've got." - Woody Hayes
Engine Team