Injection angle maps

[Volvo850r]

Does Vems have a map for injection angle?

Have been looking at the omex 710 and this has a full map for injection angle, but can t find any mention of this is the current vems version of megatune.

[rob@vems.co.uk]

Nope, we dont have them, it was considered because we could effectively re-use the ignition timing code, but it was decided against.

The reasoning for this is that sequential injection where the injector fires onto the back of the valve is simple to set up, and perfectly adequate for power and emissions.  Injection timing start points change throughout the rev range and need mapping on a dyno and will need a fast way of measuring CO and HC.  The most improvement you'll expect to see is 2-4% torque improvement in the low to mid-range and a little improvement in fuel economy (its debatable that you'll have spent more on fuel setting this up than you'll save in the lifetime of the car).  Its a bit like the complex acceleration enrichment systems, technically brilliant but almost impossible to set up any better than the simple ones.

There is a degree of fixed injection angle configuration available - this is obtained by adjusting the trigger tooth in the primary trigger settings.

[dnb]

Rob - would this trigger tooth adjustment be the one I discussed with you?

If so, then will it cause there to be an ignition timing offset?

[rob@vems.co.uk]

Yes, then you'd change the TDC after trigger value in the primary trigger settings to adjust things.

You should only need to change this when you're using batch fired injection and have HC problems, there is a narrow window of operation that will cause Hydrocarbon issues at idle due to one injector squirting into an open port.

I have never had an emissions problem that wasn't solved by injecting the port of the cylinder at TDC, as its guaranteed to be on a closed inlet valve thats either heating up as the cylinder charge ignites or still hot after cobustion on the exhaust stroke.

[Sprocket]

I second the need for injection angle maps

Can we have some experimental firmware for this!!

and ou know what im leading to

[DMS]

Are there any new developments concerning this topic?

A simple rpm/angle table would suffice.

[MWfire]

Are there any new developments concerning this topic?

A simple rpm/angle table would suffice.

yes, code is on test.

[DMS]

Cool thanks!

Guess I'll be patient then.

[kulinpapa]

For the injection agle code, also needed to be choosable that the start of injection or the end of injection angle is set. However the endof injection is better, i think.

[z0tya]

This is the Marelli strategy:

A 16 byte table below for the level 6 is used to control the point at which the injection period begins v engine rpm.


This table uses the rpm header from the fuel map as a header.
600    800    1000    1150    1350    1599    1799    1999    2250    2500    2749    3000    3498    3998    4496    5498
80    80    80    80    80    60    60    60    60    40    40    20    20    20    20    20
270'    270'    270'    270'    270'    180'    180'    180'    180'    90'    90'    0'    0'    0'    0'    0'

All angles are multiples of 90' and are taken from the cylinder being at TDC on its firing stroke (in preparation for the next cycle). At idling rpm the injection period will be short, so it is started 270 degrees late, so it occurs just before the inlet valve opens (90' before tdc on exhaust stroke). At high rpm the injection starts straight away to give maximum time for the injector before the inlet closes. Only values of 20h,40h,60h,80h are used (the larger the number the greater the delay).

[mattias]

We are looking at a "angle vs rpm" table for end of injection, and it will be accurate to at least a specific degree.
Load is not a consideration at this point, but could be a future upgrade, so it's a simple 2d table.

[SamSpade]

Sounds promising, and could result in smoother idling and/or better emissions for those with big cams and large injectors. Looking forward to it.

[dnb]

angle vs RPM will be good enough for me at the moment!  I suspect the variation with load is a secondary effect by comparison.