Here it is, as I promised... My megasquirt stuff...



I have upgraded to the new Megasquirt-Extra code. There will be pictures, schematics and explanations here eventually. Hopefully enough information so that anyone can use megasquirt instead of looking for a genuine 20v ECU when doing a 4agze or 20-valve engine swap. Information can be found st the website of the creators of the Extra code, James Murray and Philip Ringwood. I can't thank them enough for their hard work. http://www.jsm-net.demon.co.uk

Hi, this will be my megasquirt-n-spark page. but for now, here are the pictures.. I'll explain when I have time or E-mail me Twincharger@hotmail.com

This is a 1987 Toyota Corolla, model AE86. It has a 1600cc, twincam, 4 valve per cylinder, fuel injected, supercharged, turbocharged, intercooled engine. Kinda complicated...

I searched for a Toyota 4AGZE ECU, but never found one, so I put the car together using a stock 4AGE ECU, Supra Airflow meter, 4AGZE 360cc fuel injectors and a MSD 6 BTM to retard spark. I did have to re-calibrate the AFM to make the setup work. Unfortunately the setup was AFM based, instead of MAP based, and with the twincharging setup on the car, the ECU could not tell the difference between 'low rpm with high boost' or 'high rpm with no boost'. Both would flow the same amount of air, and both could happen with very small throttle angles. The timing requirements of these conditions are very different. 'low rpm with high boost' wants a retarded spark to keep from detonating, and 'high rpm with no boost' wants lots of advance to keep efficiency up. So the Throttle position sensor was not a very good indicator of engine load. Most times I could make more power at half throttle than full throttle. I knew that I needed a standalone engine management system. At the time, I could not afford to buy one, so I built a Megasquirt kit. Now there is a version of software for megasquirt that allows the same board to control fuel and spark. Megasquirt-N-spark.
This is the stock Corolla ECU, located by the passenger's feet (left-hand drive).

This is the inside of the Toyota ECU.

Since you supply your own enclosure for the Megasquirt kit, why not use the original Toyota enclosure... That way you know it will fit back into the car, and it would look sort of like it belongs there. Plus you won't have to cut the connectors off of the wiring harness and splice each wire to the megasquirt. Here is the Megasquirt board in a Toyota enclosure. Click it for a bigger view.


My thought was to use the Megasquirt-equipped ECU as a 'universal' Toyota replacement, like I could move it from car to car at will... But that didn't work because the Toyota's throttle position sensor works backwards compared to the rest of the EFI world. Idle is 5 volts, floored goes to zero. The sensor needs to be re-wired to go from 0 to 5.



Here is the almost-finished unit. Notice stock Toyota wiring harness connectors, hose for MAP sensor, 37-pin megasquirt connector, and serial port for programming. Click it for a big one.



It's fully installed now and runs pretty well. I have only begun to tune the spark and fuel maps. All settings are set to the safe side until I get time to tune some more. I will post my final fuel and spark maps here if anyone needs them.

Here are my Megasquirt settings...

I'm using 3.3 ohm peak/hold injectors with the stock toyota resistor pack. All 4 injectors are on 1 megasquirt output. My O2 sensor is narrowband and getting old.

CONSTANTS

Req Fuel 14.0	injection control 1 Squirt, Simultaneous
Inj open 1.0ms Batt = 0.1 ms/v	4-stroke, 4 cylinder
PWM current limit 30% PWM time=15.0ms	Multiport, 4 injectors
Fast idle - used for spark	Engine Stroke = 4 stroke
Control speed-density	MAP type 250KPA, Even-fire
	O2 sensor - NarrowBand, Barometer Disabled

With multiport fuel injection there is little chance for fuel to drop out of the mixture and sit at the bottom of the manifold compared to a throttle-body setup, so very little warmup enrichment is needed. Plus in AZ, the car is over 100 degrees when I go to start it, so I can get away with almost no warmup enrichment. My TPS signal was a bit noisy, so I disabled the slowest accel bin. That cleared up the symptoms. The EGO step of 1% is a huge change when you have 450cc injectors on a 1600cc engine. I can't use it at idle. My o2 sensor rarely puts out over .7 volts, so I decreased the trigger voltage to something I could hit. Maybe I should replace the sensor? Naaaahhh.

ENRICHMENTS

Cranking -40 = 12.0 170 = 4.0 Priming = 2.0 afterstart = 10% cycles = 10

Warmup enrichment bins 101,101,101,101,101,101,101,101,101,101

TPS trigger .59 Accel duration .5 Acc bins .1 , 1.0, 1.0, 2.0

cold accel enrich 0, cold accel enrich 0, Decel fuel cut 80%

EGO Active temp 175, events/step 33, EGO step 1.0 (wish it would go lower)

EGO limit 30%, EGO active above 1200 RPM, EGO volts .397

This map is a little rough around the edges, but it's okay in the range for normal driving. It's a good base map for less than 10psi of boost. This map passed a required IM-240 smog test.

FUEL MAP FOR 1600cc 4AGZE WITH 360cc (stock) injectors.

MAP
20	79	55	40	29	25	32	34	34
30	95	79	59	44	34	38	41	50
75	83	71	61	54	54	55	58	63
100	74	84	84	73	70	72	72	76
125	82	85	90	89	77	82	83	94
150	94	92	95	94	89	93	102	113
175	100	100	99	108	101	107	114	124
200	100	100	100	116	117	128	125	142
RPM	500	1000	1500	2500	3800	5300	6500	8000

FUEL MAP FOR 1600cc 4AGZE WITH 450cc (RX7 non-turbo saturated) injectors. This map is a good starting point for low to medium boost. I was mapping to about 10 psi of turbo boost, then I experienced turbo problems. A foreign object entered the turbo and ended my testing. Oh well, it will be back, bigger and better soon.

MAP
20	78	66	54	23	20	26	27	27
30	78	68	57	51	49	30	33	40
75	76	67	59	56	55	54	46	50
100	59	67	67	60	70	66	62	61
125	66	68	72	67	70	67	69	70
150	75	74	76	75	79	73	73	76
175	80	80	79	86	81	83	82	86
200	80	80	80	93	94	102	100	100
RPM	500	1000	1500	2500	3800	5300	6500	8000

The ReqFuel value for this table was calculated by assuming that it was a 3000cc engine, instead of 1600cc. This keeps the VE values down much lower than the previous map, even though these injectors are only 25% larger than the 360cc injectors. If you use this map, you may want to fiddle with the ReqFuel value before adjusting individual cells.

Megasquirt-N-spark Ignition settings.

Trigger Angle 52

Crank timing - Time based

Crank angle 10 - needs changed!

Hold ignition 2

Ignition output - Noninverted

Ignition Map

MAP
25	8	8.5	12.5	10	10	14	27	28
30	9	17	10.5	17	15	25	38	40
50	30.5	33	28.5	28	24.5	27	34	34
80	32	31	33	30	31	31	31	36
100	25.5	28	27	25	25	29	30	32.5
125	24	26	26	26	27	30	32	33.5
150	20	23	23	24	29	30	32.5	35
200	10	10	10	22	27	27	27	30
RPM	1000	1500	2000	2500	3000	4000	5000	7000

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