# spark map



## ps2375 (Aug 13, 2003)

Well, I'm trying to tune for a little better mpg's, and since I have the fuel leaned out as much as I want, the only other way is to tinker with timing. Now this is just for the rpm range on the highway to work. And after looking at some spark maps from MSRuns, I think I have my spark table setup,,, different if not wrong. I kind of built it the same way as I did for fuel, from the bottom up, based upon kpa, where as the ones I looked at seemed to have went from left to right, more based upon rpm's. 

I am also tinkering to reduce/eliminate the slight bucking in light load 2nd gear driving, like say through the neighborhood. I thought that less timing might help that. 

LMK what the prevailing ideas are on this subject, and the motor is an 8V GX coded(9:1 CR) w/ g-grind cam and a tri-y header.


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## need_a_VR6 (May 19, 1999)

Here are two of mine:

12v 10.x:1










24v 11.3:1










If you've already hit your misfire limit (surge) on the lean side, adding some timing will let you lean out even more.


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## ps2375 (Aug 13, 2003)

those look more like what I was seeing than what mine does. I guess I'll give one of those a try, with some adjustments, of course. I guess what I missed, is that timing is more dependent upon rpm than load(vacuum), except for maybe high vacuum(low load) cruising.


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## ValveCoverGasket (Mar 20, 2002)

ps2375 said:


> I guess what I missed, is that timing is more dependent upon rpm than load(vacuum), except for maybe high vacuum(low load) cruising.


sounds like youve got it now :beer:
theres a few vex files posted in the spitfire downloads section, but what paul showed is (as usual  ) exactly right...


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## need_a_VR6 (May 19, 1999)

What was your reasoning for doing what you have in your spark maps? 

In general:

RPM goes up timing goes up until you hit the critical rpm then it's flat
MAP goes up timing goes down

You'll see in the far bottom right corner those rules aren't followed, but that's more due to them being unused/tuned then anything.


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## ps2375 (Aug 13, 2003)

need_a_VR6 said:


> What was your reasoning for doing what you have in your spark maps?


 Just a lack of understanding of what I was doing. Having never had to make a spark map (or even a fuel map), I did what seemed to work and make sense, but now with more understanding and time to think about what it is and how the mechanical part should work, I realized that I was wrong and can do better.


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## ps2375 (Aug 13, 2003)

After studying the Bently Manual for the timing specs of various dizzys, This is what I came up with. I incorporated some of the changes I had made to the earlier table for the low RPM light load cruising ( I'll call it parking lot cruising). I haven't loaded it to the car yet, just made the table tonight. I'm sure it'll need some work, and the VE table will have to be adjusted, but I do have the target tables to fall back on for now.

OLD:









NEW:


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## Prof315 (Jan 5, 2009)

ps2375 said:


> After studying the Bently Manual for the timing specs of various dizzys, This is what I came up with. I incorporated some of the changes I had made to the earlier table for the low RPM light load cruising ( I'll call it parking lot cruising). I haven't loaded it to the car yet, just made the table tonight. I'm sure it'll need some work, and the VE table will have to be adjusted, but I do have the target tables to fall back on for now.
> 
> OLD:
> 
> ...


If you want to get good cruising mileage you need to jack up the low kpa timing a ton. If I were you I'd copy Paul's map and work off of it. Even with a turbo I'm running my no-boost timing based on Paul's and I am getting mid to upper 20's around town and low to mid 30's on the highway.


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## ps2375 (Aug 13, 2003)

The place I'm looking for mileage is on the highway, which is 2500-3500 rpm and 50-70 kPa ranges. The section below 40kPa and between 2400-3600 rpm is for the low speed part throttle to prevent bucking.


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## need_a_VR6 (May 19, 1999)

That cruise MAP seems high, you ever change the sample angle to try and get it lower?


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## ps2375 (Aug 13, 2003)

Not sure what you are talking about. Please enlighten me. At 70-75mph, I am right at 3k rpm and the throttle was right at the point of opening the secondary butterfly. I have not been on the highway with the new map yet, so I don't have any idea what/where it'll be now. It could be with the added timing, less throttle will be needed, which means the MAP could be lower.


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## Prof315 (Jan 5, 2009)

ps2375 said:


> The place I'm looking for mileage is on the highway, which is 2500-3500 rpm and 50-70 kPa ranges. The section below 40kPa and between 2400-3600 rpm is for the low speed part throttle to prevent bucking.


You'll never see below 40 kpa or lower at low speed part throttle ( at least i don't) If you are bucking when driving the neighborhood you are probably to lean.


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## ps2375 (Aug 13, 2003)

I do see below 40Kpa. The throttle is barely cracked and I have already tried adding fuel there. Pulling some timing seems to work best for me.
I drove it to the store last night and it seems to drive well. Later this week it'll get some highway driving.


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## need_a_VR6 (May 19, 1999)

I'm between 20-40kpa at low throttle on the highway... but I'm turning higher revs probably (3200-3500) just due to gearing. That could h


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## ps2375 (Aug 13, 2003)

I've been doing some "autotuning" with megatune, and at 70mph, 3000rpm, I'm at 55-60Kpa. Lower than I thought it was. And the low speed Kpa is 30-40. The map is leaning out in most places and has gotten richer in a few others. I might just pick-up a mpg or two. (I hope) 

I do hope to be able to some day get a registration for "Tunerstudio" to speed the process up, seems that data logging would be a much faster way of doing this. And I have read nothing but praise for that software.


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## need_a_VR6 (May 19, 1999)

The Autotuning in TS works a lot better well worth the $40.


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