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Hi all

My TPS v RPM (+ MAP compensation) map works really well, bar a few part throttle & idle niggles which I think switching to MAP as load might fix.

What's the best way to convert to MAP as load? I was thinking of taking a log file and plotting the actual injector duty vs RPM / MAP in an excel sheet? My mapper is miles away, so it will need to be done DIY initially I'm afraid.

Also, with MAP as load, say I hit 100KPA (it's a nasp engine) at 38% throttle, how do I fuel the remaining 62% of air flow? At least with TPS v RPM, I had control of that, but maybe I'm not understanding a basic concept with MAP v RPM?

Thanks!

If you hit 100kpa at 38% then there is no restriction so the next 38-100% will let hardly any extra air in.

MAP vs RPM is simple. It only gets complicated if you try and compare it to the flawed TPS method.

I think someone did write a little program to convert a file ages ago. Probably the old forum somewhere.

But your idea of using logs is sound, and really, once you have a dozen or so sites you can build a relatively good map very quickly once you see the patterns.

Likewise ignition timing is even easier.

Thanks Stevie

OK, I've got a decent log and chucked it into Excel, so can now get a basic MAP v RPM table together and then do some tweaking with closed loop. That should be sufficient to get it to my mapper.

One question though, the "Injection Pulse" logging option is a 'calculated value', so I'm guessing this would include the dead time?

In terms of writing a new fuel table, would it be better to take 0.75 (my IDT @ 14V) off the entire map, or just turn off IDT compensation and just use the numbers from the log?

Thanks!

I find it interesting that you wish to swap to MAP based, as I am wanting to try TPS w/MAP correction and haven't had a chance yet!

Regarding MAP load being atmospheric at 38% Throttle, at 38% throttle you have tuned from idle vacuum right up to atmospheric... so that is all there is! Opening the throttle more than that does nothing as the engine can not swallow any more air anyway.
I assume this is at a given RPM, obviously as RPM increases then the requirements chance per engine characteristics. At a given rpm, once you reach atmospheric the opening the throttle does not add 62% more airflow... it can't, the pressure inside the plenum and outside it has equalized so opening the throttle is not going to change anything.

I am unsure why stevie says the TPS based setup is flawed, it is certainly better for large-overlap forced-induction engines that have very little vacuum at light loads as it lets you tune far more off-boost load points for better driveability.
The DTA manual does say it lets you tune more effective load points, and is the method they recommend.

Interested to see both versions of your fuel and ignition tables from both versions once done.
It could be calculated to exclude dead time from a total injection time also, but would be a good starting point.

I just wanted to try it out of curiousity really, just to see if it would refine a few areas.

I tried the MAP v RPM map earlier and it was all over the place, lol! I think I'll just drive it to the mapper as it is and we'll try MAP as load on the dyno.

ignitionautosport wrote: I am unsure why stevie says the TPS based setup is flawed, it is certainly better for large-overlap forced-induction engines that have very little vacuum at light loads as it lets you tune far more off-boost load points for better driveability..

I guess I can correct that. Previously there was only a blanket MAP compensation.

Now with a full 20x14 compensation map to play with, it has improved.

But using the older blanket compensation, at WOT you have 1 single row for all boost pressures and rpm loads the engine might ever see.
That IS flawed.

ie 100% throttle vs RPM. The engine isnt going to consume the exact same amount of air at all rpm and map conditions for a simple compensation to apply.
In theory it should, but engines are not theoretical and different head, cam, turbo etc etc will all mean the engine behaves differently over many different loads.

VR6Turbo wrote:Thanks Stevie

OK, I've got a decent log and chucked it into Excel, so can now get a basic MAP v RPM table together and then do some tweaking with closed loop. That should be sufficient to get it to my mapper.

One question though, the "Injection Pulse" logging option is a 'calculated value', so I'm guessing this would include the dead time?

In terms of writing a new fuel table, would it be better to take 0.75 (my IDT @ 14V) off the entire map, or just turn off IDT compensation and just use the numbers from the log?

Thanks!

Good call, yes the logged values will include IDT, so your new fuel table would need to be the logged value subtract IDT.

Either way, it'll still be a good starting point.