Overlay tables

[Guest Marcel B]

Hi all , can anyone explain the overlay (6 dimension ) tables ? the manual only briefly touches on it . I tried selecting both the fuel and ignition overlay tables , but was not allowed to choose a sixth dimension , what did I miss ?

[rayhall]

Marcel,

Why do you want overlay tables. If you plan to map using TPS as the Y axis for the fuel table, then set the target AF table as enabled and Fuel Equation as Load=BAP. You then tune based on TPS and the ECU will look after the correction for manifold pressure.

[Guest Marcel B]

Hello Ray ,

I dont really want to use this feature , but my project is evolving somewhat as time goes on . I set up a two staged water injection syatem that activates under boost . Each stage has its own water flow PWM table and flow sensor . A GP PWM table (AUX # 7) is used to switch power to the boost solenoid based on water flow vs. boost . I also have a low level switch mounted in the water reservoir which connects to DI # 9 input , I have found (through an unfortunate incident :mrgreen: ) that when the reservoir goes empty its bye bye motor !

When the AUX #7 output turns on( low water flow detected) , I also want to have the tuning settings go "SAFE" by retarding ignition and richening the fuel maps. . To achieve this I have set up both the fuel and ignition dual map feature to switch to the second maps (which I have richened up and retarded respectively)when the PWM output activates.

The problem is that the idle on my HUGE street and "semi" perephial ported motor is very lumpy , it requires very little ignition and dafferent fuel settings for idle ,I am also using a pair of 1600cc primary injectors for starting , idle and low load .The motor idles fairly high too,1100 to 1350 rpm's , causing me to have to reduce the fueling and ignition in this region of the map . From past experiences , I have found the when already in motion , the car / motor stumbles when moving through this range .As we know , the V88 does not have separate idle ignition or idle fuel maps , so I decide to leave the main fuel /ignition maps alone and enable bothe the 4D fuel/ ignition maps , using them to adjust the idle part of the map , by using throttle opening (0-5%) against rpm's (0 -1500).

The only disadvantage to this approach is the fact that I am fresh out of user tables , so I thought about using the 6D table to maybe achieve the same thing and freeing up some of the user tables.

[rayhall]

Marcel,

Rather then trying to solve problems you had with other make ECU, before you have tuned the Vipec on your engine, is a bit of a waste of time. The Vipec is not the same as your old ECU.

The lack of a separate idle ignition table is more then compensated for, in most cases as the idle value control works correctly, unlike many other make ECU. You can make the main ignition table have a idle ramp, but so far I have never needed to do this. On engines with very big cams, I have had to open the throttle a little more as the stock idle valve did not have enough flow to catch the engine when coming back to idle or as AC or other loads were applied.

I would tune using the method mentioned previously and if you find that overlay tables have to be used, then and only then use them.

Ray.

[Guest Marcel B]

Ok , I will try it out first , no problem . I just like to be properly prepared , thats all . By the way can you explain more about this "You can make the main ignition table have a idle ramp," :?:

[Guest |59|]

I think Ray meant that you could increase the ignition timing values just below your normal idle rpm sites.

[rayhall]

I think Ray meant that you could increase the ignition timing values just below your normal idle rpm sites.

Yes that is correct. You make the sites just under the idle sites have more timing.

[Guest Marcel B]

Yes that is correct. You make the sites just under the idle sites have more timing.

Yes this is normaly how I set it up , but the problem comes when I am just rolling in say first or second gear with the rpm's a bit low like in traffick.When I get on the gas it would stumble as it passes through the "no timing & fuel area " (idle timing = 5 deg / AFR= 13.8-14). I have tried to fix the fuel part by increasing the acceleration enrichment map , but this still does not help with timing.

[Guest |208|]

There many other ways to impliment your tuning ideas. There are may things you can do with the anti-lag and launch control settings for example which could help your cause. You can use the antilag function to run your water injection corrections for example. Maybe your idle timing using the launch control features. Maybe even do your idle map timing and fueling overlay tables triggered off wheel speed being 0. Car moves and it reverts back to main table settings. There are many ways you could impliment these corrections. Just need to get a little creative. I agree with Ray though. You may be looking for solutions to problems that may not even exist anymore with the V88.