EDIS Ignition Control with MegaSquirt-II
Contents
1. 1997 4 6L V8 engines The EDIS 4 and 8 cylinder coil packs are available from Accel under number 140018 54 95 each from Summit Racing The EDIS system handles the complete task of crank ignition synchronization as well as current control for the wasted spark coils It sends just one signal PIP to MegaSquirt I and receives just one signal SAW back The desired amount of ignition advance is generated by MegaSquirt II The interface between the EDIS and MegaSquirt II is extremely simple There is one output signal PIP and one input signal SAW from the EDIS module MegaSquirt II On all engines the complementary coils are connected to the cylinders that are 360 i e 2 of a 720 engine cycle apart in the firing order For example the firing order for HO 5 0L and 351 engines is 1 3 7 2 6 5 4 8 Connect cylinders 1 and 6 to the same coil 3 and 5 to another coil 7 and 4 to another coil and 2 and 8 to the remaining coil Note that the coils are packages in two groups of two coils each of which fires 2 cylinders in V8 applications The operation the EDIS system is very simple The crankshaft is fitted with a 36 tooth wheel with one tooth missing The missing tooth indicates the exact position of the crankshaft to the EDIS The EDIS system is a wasted spark setup i e two spark plugs fire which are separated by 360 cycle degrees of a 4 cycle engine so there is no synchronization with the camshaft This means that one cylinder has its2. low grounded to fire the plugs The duration of the PIP signal is based on the desired coil dwell period and is calculated internally by the EDIS module The spark advance is controlled by the Spark Angle Word SAW line on the EDIS module The SAW is a pulse width of a specific duration that tells the EDIS system when to fire the spark plugs It is calculated as follows SAW ZTDC ST x T x cm where e SAW is the calculated pulse width in microseconds ZTDC is the pulse width offset corresponding to the SAW pulse width for a spark advance of 0 TDC e ST is spark advance in degrees and is negative for spark angles after top dead center ATDC T is the pulse accumulator clock period in microseconds e 2 sup x is the number of steps between position signals for a desired spark resolution and x is a whole number and e CMI is the engine crank marker interval i e the number of degrees of crankshaft rotation between signals from the position sensor A top dead center offset value is selected as 1536 microseconds i e ZTDC 1536 A clock period of four microseconds 4usec is used in the pulse accumulator corresponding to a clock frequency of 250 KHz The crank marker interval is 10 and a desired resolution within the 10 intervals is chosen as 64 discrete steps i e x 6 The formula for determining SAW pulse width is thus SAW 1536 25 6 x desired spark advance in degrees in usec Range 64 1792 usec 57 2 BT
3. sure you have a wire connecting pin 36 to pin 36 in the MegaSquirt relay board connecting cable e the PIP signal connects to the Tach terminal 15 on the 20 position terminal strip on the relay board it goes to DB37 pin 24 Here are the EDIS pin outs for the EDIS4 EDIS 6 and EDIS 8 EDIS Ignition 8 av 10 EDIS 4 Wiring Connector shown looking imio wining baraess PIP to DESF pin 24 DAW to DESF pin 36 ewitched 12W main relay Note that the EDIS 4 and EDIS 8 key are similar but swapped from end to end Do not attempt to connect them you will ruin the module wiring and or coil packs In all case the clip is the most useful guide to the pin numbering Pin 1 is usually marked on the connector Spark Plug Wiring There are a number of principles to wiring the spark plug leads to the coils and a number of gotchas e A single coil two towers vertical when the connector is at the bottom should fire cylinders that are 360 apart in the firing order For example if your firing order is 18436572 then 1 amp 6 8 amp 5 4 amp 7 and 3 amp 2 should be connected to the same coils they are called complimentary cylinders e Do not confuse the firing order with the coil terminal numbering e Coil A fires first 1 e correct for cylinder 1 so it should be connected to cylinder 1 and the complimentary cylinder It doesn t matter which terminal on a coil goes to which of the two complimentary cylinders since
4. they both fire the one on the exhaust stroke using vary little spark energy because of the ionized exhaust gases e 4cylinder EDIS4 o Ona four cylinder engine with a firing order of 1342 that means the coil should be connected so that 1 amp 4 are on coil A left side when connector is at bottom and 2 amp 3 are connected to coil B right side Other firing orders are connected differently Basically you connect 1 and the third cylinder in the firing order to coil A and the second and fourth cylinders in the firing order to coil B o On EDIS4 coil A is connected to pin 10 of the EDIS module coil B is connected to pin 12 of the EDIS module If these are connected the wrong way around the coils will fire in a different order and the spark plug wires will need to be rearranged EDIS Ignition 9 av 10 e Cylinders may be numbered in different ways depending on the manufacturer Inline four cylinders are generally 1234 from front to back with the front being the opposite end from the transmission Vee and flat engines might be numbered with even numbers in one bank and odd on the other or they might be numbered down one bank then the other ALWAYS check in a service manual to be sure e Given the number of potential problems firing order cylinder numbering module to coil wiring the best advice is from James Murray http megasquirt sourceforge net extra edis hardware html One method is to test on the starter plugs out Fi
5. DC to 10 ATDC Resolution 4 psec 32 of a degree EDIS Ignition 5 av 10 For example for 36 of advance we want MegaSquirt II to send a SAW of SAW 1536 25 6 x 36 in usec 1536 922 usec 614 usec The width of the SAW word in degrees is related to the desired advance by the above equation At first glance it looks odd but it does make sense depending on the hardware generating the width With a microcontroller timer peripheral most timers use a counter 16 bits in length and they have a mode known output compare which is used to make an output toggle when the counter reaches a comparison value Using a 16 bit timer incrementing at a 1 microsecond rate and a 16 bit comparison register to toggle the output one can easily generate the required period In fact the numbers are quite easy to use see the following table for example SAW advance widths and corresponding 16 bit timer compare values Advance SAW Pulse Width High order 8 Low order 8 Degrees usec bits bits 10 1280 0x05 0x00 20 1024 0x04 0x00 25 896 0x03 0x80 30 768 0x03 0x00 40 512 0x02 0x00 50 256 0x01 0x00 sae 128 0x00 0x80 The numbers now make a little more sense The high order of the 16 bit timer drives every 10 degrees and the lower 8 bits drives the advance values in between This makes generation of advance widths very easy with a microcontroller The Ford engineers knew what they were doing The PIP signal is used as a ref
6. EDIS Ignition 1 av 10 EDIS Ignition Control with MegaSquirt II The Ford EDIS System Ford s Electronic Distributorless Ignition System EDIS is an ignition system that does NOT require a cam position signal It can function with just a variable reluctor crank position sensor and a 36 1 tooth wheel 36 1 means 36 teeth minus one and refers to 36 evenly spaced teeth one of which has been removed For a custom 36 1 wheel for a small block Chevrolet see www megamanual com ms2 36 1 htm Because it doesn t need a camshaft position sensor EDIS is a particularly easy way to replace distributor ignitions when retrofitting older engines with a modern computer programmable ignition To understand the inner workings of the EDIS module read US patent numbers 4 661 778 4 922 874 and 5 014 676 at www uspto gov However to use the EDIS on your engine you don t need to know it s internal workings MegaSquirt II and EDIS i co l pack s Engine a TDC missing t j j i i i y tocth 5 teeh anead of J MegaSquirt II sensor ELIS 8 l PATE i A F gt p v VWE sersor 35 1 tooth crank wheel viewea fombehird The EDIS system is made up of EDIS module crank wheel crank variable reluctor sensor VRS and one or more coil pack s This section deals with the operation of the Ford EDIS Electronic Ignition Module There is a lot of information on the modules on the web bu
7. Using a two channel scope and monitoring the VR waveform and coil 1 output from the EDIS module it is easy to see the relationship Various SAW Advance Commands Effect on Firing SAW Width 1024 us 20 Degrees SAW Width 768 us 30 Degrees Fire 1 Coil SAW Width 512 us 40 Degrees i Fire 1 Coil SAW Width 256 us 50 Degrees Fire 1 Coil EDIS Ignition 7 av 10 A significant part of the whole EDIS module is the multiple coil drivers First thing is that the EDIS module has the actual ignition coil driver built in the driver is not part of the Ford wasted spark coil pack The coil packs are just standard ignition coils and could in theory be substituted with other coil only packs The EDIS 8 module has four coil drive channels EDIS 6 has three and the EDIS 4 has two The EDIS module handles the dwell time automatically depending on commanded advance and RPM another feature which makes the EDIS one of the easiest to use DIY setups The EDIS ignition system is rugged The module mounts under hood and will survive engine bay temperatures water freezing etc And with only two wires going back to the MegaSquirt II box PIP and SAW wiring is extremely easy Installing the Ford EDIS System Note that the PIP signal from the EDIS module to MegaSquirt is like a Hall sensor signal positive only square wave As a result you use the Hall input circuit On a V3 board jumper D1 and D2 or install jumpers in their place
8. ative transition which occurs when the VR sensor tip is aligned with the crank wheel tooth Using the VR signal and the missing tooth wheel the EDIS module can synchronize with the engine crankshaft Here is a picture of the simulated VR signal generated from the crank wheel and the EDIS 8 firing point for coil 1 EDIS Ignition 4 av 10 Default EDIS Advance no SAW commanded advance Missing Tooth iA Fire 10 Degrees Advance When the EDIS module receives proper a VR signal it generates a 12 volt square wave signal with a period linked to the next cylinder to fire In other words when this signal Ford calls it the PIP for Profile Ignition Pick up goes from 12V to ground one of the ignition coils is firing This signal follows the ignition coils not the VR sensor as indicated on some incorrect documentation floating around For an EDIS 8 module there will be four complete cycles of the PIP waveform for every 360 degrees crankshaft or thirty five VR signal cycles not 36 because of the missing tooth An EDIS 6 will yield three PIP cycles per every 360 degrees crank and an EDIS 4 gives two For example with an EDIS 8 we have 9 VR sensor cycles or 8 if the missing tooth is in that sector for every 90 of engine rotation and this corresponds to the period between coil firings on two cylinders one of which is wasted So during this period the coil has started low gone to 12 volts to charged the coil then gone
9. eceives a Spark Angle Word SAW command The 10 advance is constant regardless of RPM This functions as a limp home mode if the module doesn t receive SAW commands from MegaSquirt IJ it will generate a usable but not optimal 10 BTDC of ignition advance To test the VR sensor alignment run the EDIS in limp home mode This can be done by disconnecting the SAW PIP plug or disconnecting MegaSquirt II or its power Start your engine and check that the timing is exactly 10 BTDC with a timing light on cylinder 1 If the timing isn t 10 BTDC adjust the position of your VR sensor until the timing is as close to 10 BTDC as you can get it Don t forget to reconnect the SAW PIP plug when you are done or you will have NO timing advance and your engine will run poorly and inefficiently The VR sensor signal polarity is such that when the tooth tip is exactly centered on the VR sensor the VR output is at zero volts falling from a positive to a negative polarity i e a zero crossing with a negative slope The VR signal is fed directly into the EDIS module to indicate the crankshaft s position The EDIS module handles all VR signal processing In fact the EDIS module has a built in VR signal hysteresis when the VR signal is passing from negative to positive polarity next tooth is approaching the signal must reach 0 5 volts before the EDIS module will arm It then will trigger when the signal passes through zero on a positive to neg
10. erence to synchronize the generation of the SAW pulse by MegaSquirt II The SAW signal is generated by MegaSquirt II and is an input to the EDIS module This signal is a 5V positive square wave pulse and the width of this pulse determines the advance that the EDIS module will use for subsequent ignition events up to a half second or so If the SAW signal is lost for much longer than this the lim home mode is enabled and advance is set at 10 BTDC So the SAW signal does not have to be sent on every PIP cycle the EDIS module will remember the last SAW commanded advance and remember it for subsequent ignition advance values until a new pulse is received or until limp home mode is enabled Note that the SAW pulse must be synchronized with the PIP negative going pulse i e when the PIP drops to zero It cannot be applied asynchronously to the PIP signal otherwise incorrect advance commands will be interpreted by the EDIS module SAW should be initiated a short period after the falling edge of the PIP signal Here is the proper relationship between the two signals EDIS Ignition 6 av 10 EDIS PIP and SAW Signal Relationship N PIP SAW Note that there is some uncertainty over the exact timing relationship between the two signals for some EDIS modules The range of the spark advance word is from 59 60 would be a pulse width of zero and the previous SAW would be used down to 0 How does one measure this
11. rst mark your crank pulley with where each plug should fire and then strobe each coil tower in turn as you crank the engine to see which one fires e g I was installing MSnEDIS onto a small block Chevy which has 18436572 firing order so I marked I at TDC 8 at 90 ATDC i e a quarter turn anti clockwise then 4 at 180 ATDC then 3 at 270 ATDC You can just chalk the numbers on roughly When you have worked out which plug is which connect up the wiring and off you go Remember that the coil fires a pair of towers so in my example 1 amp 6 8 amp 5 4 amp 7 3 amp 2 are the pairs Note that most timing lights that let you set the timing with a dial and read the alignment of fixed TDC marks with the strobe will not work with EDIS This is because these timing lights use the time between sparks to compute the engine speed and advance but the EDIS wasted spark is giving sparks twice as often as the timing light expects for a given rpm If you have a dial back timing light set the dial to zero and use a degreed damper or timing tape to view the advance Settings MegaTune In MegaTune set e Trigger offset 0 this will vary depending on the wheel pickup configuration Ignition Input Capture to Rising Edge Falling Edge for MicroSquirt only if using the VR input circuit not recommmended e Cranking Trigger to Calculated e Coil Charging Scheme to EDIS e Spark Output to Going High Inverted Going High Inver
12. spark plug firing during the valve overlap period near top dead center but because the pressures are so low and the charge is diluted by the exhaust gases no ignition occurs This spark is wasted on a cylinder that isn t firing and EDIS is referred to as a wasted spark ignition system Near the crank wheel is a Variable Reluctance VR sensor this sensor produces a bipolar signal The VR sensor is pointed at the center of the crank wheel with a 0 030 to 0 060 inch gap 0 75 mm to 1 5 mm to the crank wheel teeth EDIS Ignition 3 av 10 Me spa a 4 90 6 60 8 50 10 26 The VR sensor and 36 1 crank trigger wheel must be set in the correct relationship to each other With the engine at TDC for cylinder 1 this relationship is e EDIS 4 missing tooth is exactly nine teeth 90 ahead of the VR sensor e EDIS 6 missing tooth is exactly six teeth 60 ahead of the VR sensor e EDIS 8 missing tooth is exactly five teeth 50 ahead of the VR sensor Note that you have a choice where to place the sensor IF you can shift the wheel It is a good idea to build the VR sensor bracket so that you have a degree of radial adjustment closer farther from the wheel and angular adjustment closer further from TDC Also bear in mind that most automotive engines rotate clockwise when viewed from the front except many Honda engines With the above configuration the EDIS module will fire the ignition at 10 BTDC unless the module r
13. t much of it is incorrect or incomplete The information here was derived from direct testing on the bench as well as sources like the DIY EFI list Additional detailed information provided by John DeArmond James Murray MSnEDIS Perry Edwards and a few other key sources were very helpful in figuring out proper module operation You can get complete EDIS setups including the crank wheel sensor modules spark plug wires and harnesses from Boost Engineering The EDIS 8 amp EDIS 6 modules are also available from a number of manufacturers for about 180 The EDIS 4 module can be found for around 100 Here are some part numbers EDIS Ignition 2 av 10 EDIS 4 AC Delco 19017159 F1945 Autotune PT6909 BWD CBE114 GP Sorenson EL162 DY630 FOCF12A359AB FOCF12A359AC FICZ12A297A F1CZ12A297B F1CZ12K072A F1CZ12K072B NAPA Echlin TP500 TP515 Motorcraft Niehoff FF424A Standard LX239 Wells F140 F157 If you go to a salvage yard for EDIS modules they are usually located in the engine compartment on the driver s side inner fender The modules have a EDIS 4 or EDIS 6 or EDIS 8 depending on number of cylinders sticker on them Try to take the connector as well as well as the ignition coil pack s and connectors You can also obtain used units from the salvage web at www car part com The EDIS can be found on e EDIS 4 1990 to 1993 1 9L 4 cylinder engines e EDIS 6 1990 to 1995 4 0L 6 cylinder engines and e EDIS 8 on 1990 to
14. ted for MicroSquirt Set the predictor algorithm option to last interval DO NOT set the missing tooth settings the EDIS module takes care of the 36 1 wheel MegaSquirt II sees it as a regular distributor Tach Interface For your dash tachometer you have a few choices e You may be able to use the IDM Ignition Diagnostic Monitor output to drive the tach IDM a signals that the primary side of the ignition coil has fired Simply wire the IDM output pin 2 on all the EDIS modules to the tach input OR e If your tachometer was previously driven by a single coil and the IDM signal doesn t work your tachometer will need input from two coils to indicate properly The trick is that you need to tie all the coils together without allowing them to ground each other Below is a simple circuit with Digi Key part numbers showing how to interface the EDIS system with your tach EDIS Ignition 10 av 10 to tachometer D3 1N4746ADICT ND D1 D2 1N4004DICT ND 1N4004DICT ND side of coil 1 side of coil 2 The schematic shows how to do this on a 4 cylinder two coils For a 6 cylinder you would simply add another 1N4004 to the negative side of the third coil connected to the single 1N4746 like the other two For an eight cylinder you would add two more 1N4004 diodes one for each additional coil in addition to those shown above Be sure to get the bands pointing the right way Last Updated 09 21 2008 21 32 14
15. when assembling The SAW signal from MegaSquirt II to the module comes out on pin 17 of the 40 pin socket labeled IGN and is connected to the 5 hole of the JP1 socket pin 8 of the MC9S12C64 on V2 2 boards JS10 on V3 0 boards The PIP signal goes to MegaSquirt II via the DB37 pin 24 This is connected to pin 14 of the 40 pin socket IRQ and pin 1 of the MC9S12C64 processor To install EDIS with MegaSquirt II you connect V2 2 main board e the 5th hole of JP1 to the SAW pin 3 on the EDIS module which you can jumper to an unused DB37 pin if you want e the PIP pin 1 on the EDIS module to DB37 pin 24 e Make sure D8 the John Zener diode is jumpered V3 0 main board e DB37 pin 36 to the SAW pin 3 on the ignition module e DB37 pin 24 to the PIP pin 1 on the ignition module On the V3 0 main board o use the Hall sensor circuit step 50 a in the assembly guide jumper D1 and D2 o jumper OPTOIN to TACHSELECT on the bottom side of the PCB near the DB37 connector opposite the heat sink o jumper TSEL to OPTOUT on the bottom side of the PCB near the center e jumper JS10 to IGN this uses the processor port for the SAW signal directly jumper XG1 to XG2 on the bottom side of the PCB near the 40 pin socket If you are using the relay board with a v3 main board e the SAW signal connects to the S5 terminal 11 on the 20 position terminal strip on the relay board it comes from DB37 pin 36 make
Download Pdf Manuals
Related Search