Oxygen and timing- tuning strategy- John N. whadayasay

[Guest Anonymous]

So heres what I am thinking. Now I have this nifty device that can record o2 and rpm and graph it very accurately. But timing- that is a good problem.

Is it true that the goal of the ignition timing is to get a complete burn?

That would mean that given no change in A/F ratio but a change in timing I would see a difference in O2 readings- right? If so then I can find the best timing for each range by making adjustments and looking for the lowest o2 readings-ie most complete burn. could I use this method to find the best timing for a given rpm and then plot a curve for the range by methodically testing every 500 rpm or so?

[Guest Anonymous]

Timing affect egt, egt affect 02sensor, if not a wide band, more if not heated(3-4 wire 02 sensor)

Do your own conclusions

Pat

[Guest Anonymous]

what is the relationship between timing and EGT? Is it just a matter of how much combustion is taking place in the exhaust? Can EGT be used to figure timing curves?

[Guest Anonymous]

URL: http://www.faqs.org/faqs/autos/gasoline-faq/part3/section-1.html

(nt)

[Guest Anonymous]

EGT would seem to be tough to use as an accurate and repeatable constant for timing set. Do you have a temp sensor in the system, like the modern cars do?

[Guest Anonymous]

(nt)

[Guest Anonymous]

If you're trying to get the optimal timing, you're going to need to adjust both the amount of fuel you supply and the timing for each load point on the engine.

Engine load is difficult to measure directly without a dyno, for a practical solution, you could either use some sort of a MAF sensor to measure the amount of air you're pulling in or measure MAP (absolute pressure in the intake manifold). Both give you effectively the same information. Because it is difficult to keep a constant load on your engine (outside of a dyno that is), this means you need to log a lot of points, sort through them and try and identify the valid data from the misc. crap. There are some tools some of the MegaSquirt guys wrote that you might be able to adapt (check the group archives for MSTweek).

I'm going to be firing up my electronically controlled (Ford EDIS) spark system soon, but I was going to start with the original Tii distributor map and pretty much leave it alone until I started to add boost.

The 'ultimate' solution is to measure the ionization in the cylinder after combustion. There is apparently some interesting work going on that indicates you can use the ionization to determine the precise optimal spark advance. I think I lost the papers in a computer crash, but if you're interested I could go look for them again. Measuring the ionization is one of the goals of the UMS (Ultra MegaSquirt) project I posted about earlier.

Cheers!

John N

[Guest Anonymous]

from one engine speed to another (totally consistent) for my test and just set the timing for this load (still using the stock distributor without vac advance) How will timing effect the o2 content of the exhaust?