Injector deadtime - should I increase it?

[soldave]

You might have been reading on a couple of threads that I'm wrestling with Tunerpro at the moment. Next thing on the list of things to look at in this software is injector deadtime. At the moment, it is set up in the following way:

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I know the values on the x-axis are voltages, but am not exactly what they are. Anyway, the deadtime is set up for the stock 510cc injectors. I have now upgraded my Evo to 560cc injectors and was wondering if the deadtime needed to be increased. A couple of people on DSM forums have said that 560cc injectors need a deadtime compensation of 180 microseconds. Would that mean making all of these values 180, increasing all values by 180, or something else? Just seems a big increase going from 10 to 190 microseconds of deadtime.

I do know to work this out something called the "multiplier might be used". Someone else (their name I forget at the moment) wrote this:

MAGIC MULTIPLIER for EVO III: 24
MAGIC MULTIPLIER FOR 1G DSM: 24
MAGIC MULTIPLIER FOR 2G DSM: 15

Thanks in advance

 

[steve]

Which 560cc injectors are you using? The ND560 injectors from the EVO 8 and 9 are actually faster than the stock 450cc injectors used on the DSM and faster than the 510cc you had. Those need less deadtime.

Based on your screen shot I'm not sure you have the right memory location for the deadtime table or else the factors are off. In the DSM code the stock deadtime values are in units of 24 ms and range from over 4000 ms at 4.7v to 456ms at 18.7v.

 

[soldave]

I was using stock Evo 1 510cc injectors and now have 560cc injectors straight out of an Evo 6.

Also, I have checked the Evo 3 code and .xdf definition file and the injector deadtime is mapped to the right location (73EC/73F2). But I have been blonde and made a mistake. I had the figures as decimals and not as microseconds. This should look a little better below. Can you tell I'm only just starting out with this?!

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[steve]

Much better.

Using the older EVO 6 560cc injectors I'd try adding 6 or 7 to chip deadtime values (144 or 168ms) and see what the fuel trims do.

 

[soldave]

OK. What should I be looking for, as far as fuel trim goes?

 

[bling5tatus]

If I am correct you want your fuel trims to be 100%... and if it were a 2g you would want 0%.... but yeah... >100% is lean and <100% is rich for a 1g.

Pretty interesting that you have an evo1. Where'd you get your xdf from? Have you considered getting an Ostrich from moates.net? It would make tuning your eprom much less of a pain in the ass.

 

[steve]

When it come to figuring out deadtime you really want the low, mid, and high fuel trims to be equal. Doesn't matter if that's 85% or 115%. You fix the difference from 100% with the global.

Since deadtime is a larger factor of short injector pulse widths than long, the low trims will vary more than the high if the deadtime is off. Extra deadtime makes the car richer and not enough make it leaner. On 1G turbo DSM ECUs the deadtime value in the ROM is in units of 24uS.

 

[soldave]

If I am correct you want your fuel trims to be 100%... and if it were a 2g you would want 0%.... but yeah... >100% is lean and <100% is rich for a 1g.

Pretty interesting that you have an evo1. Where'd you get your xdf from? Have you considered getting an Ostrich from moates.net? It would make tuning your eprom much less of a pain in the ass.

I've actually got an Ostrich and I managed to find an xdf on the net. Sent messages on a bunch of forums asking if anyone had one, and one person emailed one to me. There's one guy I know on a UK forum who knows a hell of a lot about the early Evo map.