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boxer engine Fuel / Spark table for Megasquirt

6K views 12 replies 4 participants last post by  LoneWolf33 
#1 · (Edited)
Hello everyone

Maybe someone has any fuel / ignition table examples for boxer engine.
no matter it is 1.5 / 1.6 / 1.7 8/16 valve, just need to understand whole picture +-.
electronic injection.
or if you have any numbers about standart injector cc/min numbers please let me know.
any info about MS configuration would be helpfull.
 
#2 ·
Hi,

For blue-top Bosch injectors used in the 1.5 and 1.7 8V engines the flow rate is 149 cc/min
at 3 bar fuel pressure.
These were fitted on the 145/146 boxers in the very beginning of the production period (before 1995),
later the whole injection system (including the injector valves) was changed from Bosch to GM.
For yellow-top Bosch injectors used in the 1.7 16V engines the flow rate is 189 cc/min
(also at 3 bar fuel pressure).
 
#4 ·
thanks for info.
this is a bit hardcore question i think, will post this to MS forum, but in case any boxer lover knows it better please take a look at this:

have some thoughts about boxer injection

fuel injectors are connected in pairs (1&2 and 3&4)
ignition coil runs 1-3-2-4

in Megasquirt i have two options:

2 Squirts per engine cycle (720 degrees) / Simultaneous- half inj dose each squirt:
000 degrees 1&2 pistons TDC / 3&4 pistons at the Bottom - ALL injectors squirt half fuel
180 degrees 1&2 pistons at the Bottom / 3&4 pistons TDC - no injection
360 degrees 1&2 pistons TDC / 3&4 pistons at the Bottom - ALL injectors squirt half fuel
540 degrees 1&2 pistons at the Bottom / 3&4 pistons TDC - no injection
720/0 degrees starts the second cycle

4 Squirts per engine cycle / Alternating - half inj dose each squirt
000 degrees 1&2 pistons TDC / 3&4 pistons at the Bottom - 1&2 injectors squirt half fuel - OK!?
180 degrees 1&2 pistons at the Bottom / 3&4 pistons TDC - 3&4 injectors squirt half fuel - OK!?
360 degrees 1&2 pistons TDC / 3&4 pistons at the Bottom - 1&2 injectors squirt half fuel - OK!?
540 degrees 1&2 pistons at the Bottom / 3&4 pistons TDC - 3&4 injectors squirt half fuel - OK!?
720/0 degrees starts the second cycle

both methods work. maybe there is a difference but i did not feel yet.
but why?
isn't 2 Squirts per eng cycle (720 degrees) bad for 3&4 cylinders filling? they always get fuel on the top of closed intake valve.
4 Squirts alternating seems a lot better?

at high speeds it does not matter i think, but at idle must be squirted correctly.
original ECU manual says: inj is semi sequental / fuel is injected half dose at each turn of the crank.
should i understand this as 4 squirts alternating?
 
#5 ·
Really makes no odds. With carbs the fuel is being 'injected' all the time, with some earlier fuel inj systems it was also a constant stream, and in some applications a modern injector might have a very high duty cycle under max load so it's open most of the time anyway. Makes no real difference at idle, and at 7000rpm the fuel doesn't get much chance to hang about on the inlet valve...
 
#7 ·
Semi sequential injection was used only on 145/146 1.7 16V boxers.
Using sequential or semi sequential injection results better emissions.

These injection systems are often equipped with a secondary position
sensor as well (e.g. the 145/146 1.7 16V has a camshaft sensor),
with this it's possible to perform more accurate injection (and ignition)
timing.

Injection should start as soon as the intake valve starts to open,
this might not exactly at TDC.
 
#8 ·
yeah ;)
want to make clear:
1.6 8v runs semi-sequential (no cam sensor)
1.7 16v runs full sequential (has cam sensor)

wired Megasquirt to 1.6 for training purposes, cause it is a bit simpler, without cam sensor and i am not afraid to break this engine etc. later, when tune it, run on dyno and start with 17 16v
(do not know if it is worth to use full seq inj in 1.7 16v, more wiring/extra hardware circuit in MS, if you say there is any performance gain, so maybe semi-seq would be enough)

1.6 already runs like a hell, only detonated a lot above 4000 rpm at wide open throttle and spark 20-30 advance, had to lower to 5-10.
strange, 1.7 16v standard ecu runs at 22 advance at WOT, 1.6 should take >20 advance too i think.
wired wide band lambda, today will see what is happening at high rpm, maybe just running too rich/lean.
 
#10 ·
:classic: I meant originally semi-sequential injection was used only on the 145/146 16V boxer engines with the Bosch ML2.10whatever ECU.

From power point of view IMHO there's no difference between sequential or semi-sequential injection, the goal is to maintain AFR around 12, when the throttle(s) are wide open.
With the feedback of wideband sensor this can be achieved relatively easy.

If you keep the plastic vacuum union on the 16V engine, there will be
adequate vacuum to drive a MAP sensor and the brake servo drum plus
the fuel pressure regulator as well. (Full MAP mode)
 
#11 ·
sadly i have only ~50% vacuum with 1.7 than 1.6
megasquirt also states, that 4 throttles does not give enough vacuum to work with MAP

but today i have another interesting story.
how much is Trigger wheel angle offset with 1.6 8v? (rpm sensor angle?) i thought it is 270, but my strobo lamp fires at 50 degrees if i make 0 advance at MS and connected to spark no.1 :paranoid:
connected original ECU, strobo fires at 30 degrees advance. a bit strange too, i think it must be around 10.

so:
if i make trigger angle 270, engine works fine, strobo shows 50 adv
if i make trigger angle 280, engine works a bit hard, strobo shows 30 adv
if i make trigger angle 290, engine shuts down after a few secs, so no way to know strobo numbers

not strange if engine detonates if i make >20 advance, maybe i get around >50 then..
 
#12 ·
so, primary job done, fun to drive, but i can not believe 1.6 8v can take only so little advance..
at low rpm WOT i hear detonation from 10 deg advance, at high rpm even lower so it is safe only at ~5 adv.

below is some visual stuff :) ignition map is not the smoothest in the world, but it works for now.
if anyone has original 146 1.6 8v advance numbers, please let me know.!

AFR table i generate myself, it is very easy to change this map and get richer/leaner results where i want. VE fuel map always stays the same (it is reference for final calculation), it is generated by Tunerstudio collecting info using wideband lambda driving on the road (real 14.7:1 map)

without knock sensor it is very hard to fine tune it further, of course i hear then it pings, but high rpm can mask it. made rpm limit at 6500 rpm.
for now will test it on the road, there are a lot of things to learn yet :)
 

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#13 ·
sadly i have only ~50% vacuum with 1.7 than 1.6
megasquirt also states, that 4 throttles does not give enough vacuum to work with MAP
For me it's a bit strange, because the combined vacuum of the 16V engine is enough to operate
the mechanical fuel pressure regulator valve, as far as I can tell the same regulator valves
were used on the 8V and 16V engines within the Alfa 33 serie (except the 1.4 IE
with IAW injection). And if a mechanical regulator can be driven, a MAP sensor, containing no
moving parts shouldn't be a problem for the engine either. Bit this is just my opinion :classic:

For the 1.6 engine I don't have the max advance data, but it was 32 degrees on the 1.7 IE (8V)
engines @ 5250 RPM, measured with WOT. Beyond this RPM, the advance wasn't increased further.
Even if the advance curve is within the factory specs, detonation could occur when the
mixture is too rich for the actual engine conditions, so I think the ping problem can be approached
from the mixture side as well.

Please let us know your further results and experiences :beer:
 
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