Author Topic: Injector Sequence for 6 Cylinder Engine  (Read 9451 times)

Offline antonch

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Injector Sequence for 6 Cylinder Engine
« on: August 21, 2007, 03:35:57 am »
I have an engine that has the standard firing order 1-5-3-6-2-4 [BMW m50 motor]. The engine is running without Cam Sync.

What is the proper sequence for MegaTune? Thanks in advance.

Wiring configuration according to PhatBob's guide:
# EC36-pin7 to Injector1
# EC36-pin19 to Injector2
# EC36-pin8 to Injector3
# EC36-pin20 to Injector4
# EC36-pin9 to Injector5
# EC36-pin18 to Injector6

Offline rob@vems.co.uk

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Re: Injector Sequence for 6 Cylinder Engine
« Reply #1 on: August 21, 2007, 08:32:54 am »
In Settings->Injector Settings
Divider = 1
Alternate banks from h[0] = 5..0


In Settings->Injector Outputs
0 = 8
1 = 2
2 = 32
3 = 4
4 = 16
5 = 1


If you then set
6 = 64
7 = 128

You'll be able use these channels for outputs for other functions, for example in Extras->Idle Settings General you can set the idle solenoid to be driven by EC36-pin17 by setting Idle Solenoid Channel to INJFET and Idle Solenoid Channel # to 7 and of course EC36-pin6 can be used with the settings INJFET 6

Offline antonch

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Re: Injector Sequence for 6 Cylinder Engine
« Reply #2 on: August 21, 2007, 10:26:59 am »
Cool, this part makes sense to me so far. From what I understand, this is just firing order (except that the ECU reads the table from the bottom up).

Will this fire injectors sequentially or in a batch once every revolution?

Offline rob@vems.co.uk

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Re: Injector Sequence for 6 Cylinder Engine
« Reply #3 on: August 21, 2007, 11:27:04 am »
Yep, it reads them from 5 to zero and in sequence.
If you wanted batch firing you'd set Alternate banks from h[0] to 0 and add the channels together ( 1+2+4+8+16+32 = 63) and set h[0] 0 to 63. 
This would mean that the injectors fired on every trigger event, so you'd either want to set the divider to 6, or set divider to 3 and inject half as much fuel by halving your req_fuel.

You could inject a pair of injectors at a time by Alternate banks from h[0] to 2..0 and working out the firing pairs like so:
Injectors 1 & 6 = 1 + 32 = 33
Injectors 5 & 2 = 16 + 2 = 18
Injectors 4 & 8 = 4 + 8 = 12
Then in  Settings->Injector Outputs
0 = 12
1 = 18
2 = 33
Then you can set your divider to 2 or keep it at 1 and half the req_fuel.

The disadvantage in this is that you loose fuelling resolution, as you're spreading the injection amount across two events which doubles the injector ramp_up and close time errors (unless you have perfect injector models).  And with batch you will always be injecting into an open valve which wont help your idle characteristics or MOT emissions.

So its best to inject sequentially in the engines firing order, with a cam sync you're guarenteed to inject on the firing stroke and therefore a closed valve.  Without it you will either fire on a ignition or exhaust stroke which is just as good.  And thats why I never bother with Cam sync ;D