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Thread: Crank timing for COP 4AFE/7Afe

  1. #16
    Junior Member Backyard Mechanic jondee86's Avatar
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    Default Re: Crank timing for COP 4AFE/7Afe

    I don't know how the ECU uses the Ne (rpm) signal, but looking at the 4-tooth wheel I can see that it will generate a signal every 90deg of cam rotation which is every 180deg of crank rotation. Sequential ignition on 4 cylinder engines (either COP's or distributor) requires an ignition event every 180deg of crank rotation. So if the pickup is located in a position that generates a signal at 10deg BTDC, then that will give the 10deg of ignition advance that most Toyota ECU's use for base ignition timing.

    A 24-tooth wheel on the cam has 15deg between teeth which equates to 30deg at the crank. Thus by counting teeth after a reset the ECU can calculate the crankshaft position every 30deg. I suspect (but don't know for sure) that by calculating the time interval between these teeth passing the pickup, the ECU can calculate the engine rpm.

    A 36-1 tooth crank pulley has 10deg between teeth This allows greater ignition timing accuracy but can limit maximum rpm as the time interval between teeth gets too short for accurate counting. If the Speeduino controls ignition and the ECU controls fuel they will be synchronised mechanically no matter what trigger wheel they use. I do think it might be easier if they both shared the Ne signal.

    Cheers... jondee86

  2. #17
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    Default Re: Crank timing for COP 4AFE/7Afe

    Why don't you use a 24 tooth wheel on the crank pulley and make a sensor and mount to run of the camshaft?

    The dist you have now has a 24 tooth and a 4 tooth signal.
    The ECU does not know or care which cylinder is firing, as there is a rotor and cap to work out which cylinder needs the spark.
    This ECU cannot run sequential ing or fuel because of this.

    If all you want to do is make it tidy by running 4 coils,
    then why don't you use a 24 tooth wheel on the crank pulley
    and make a sensor wheel with 4 teeth and mount a sensor to run of the camshaft?
    They would have to be VR sensors and about the same resistance as the originals to work,

    then you could run 4 coils all triggered off the single IGT signal as per post #4 on here.

    Using a 7AFE oil pump with a built in sensor may be an option for you with a FE head,
    as they are a VR sensor,
    but so far cant get it to work with a GE head as the number of teeth to drive the cambelt is wrong.
    I am not sure what size the 4AFE cam wheels are, but I guess they will be compatable with 7AFE.
    - KE70 Corolla Dx -
    - 500hp+ 7AGTE 20V turbo -
    - MRS/Hayabusa turbo **sold**
    - TA63 3TGTE project in the build -

  3. #18
    Junior Member Backyard Mechanic jondee86's Avatar
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    Default Re: Crank timing for COP 4AFE/7Afe

    Something more to consider, although I haven't seen it done it could work

    To put everything on the crank and have it work with the factory ECU you need two pickups and a means of triggering them separately. So a conventional 12-tooth trigger wheel with a radially mounted pickup and two capscrews or similar into the face of the trigger wheel with an axially mounted pickup. With a bit of cunning it should be possible to design a bracket capable of holding both pickups and allowing a bit of adjustment for fine tuning the timing.

    If mounting to the crank becomes too difficult, then the same approach can be applied to mounting on the front end of the camshaft only with 24 and 4 tooth pickups. This doesn't offer any performance advantage over just leaving the base of the distributor where it is now except it could be lighter and more compact.

    The bracket needs to be rigid and have enough fixing points to avoid vibration as the gap between the tooth and pickup is small.

    Cheers... jondee86

  4. #19
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    Default Re: Crank timing for COP 4AFE/7Afe

    Have a look at this it might help
    https://racerxfabrication.com/mr2-ce...z-coil-on-plug

  5. #20
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    Default Re: Crank timing for COP 4AFE/7Afe

    Sorry for not responding for a bit i had exams.

    But spend last day in the garage and rewelded my moutormounts to get a better pinionangle. While i were there i addad a sensorholder to the motormount, and fitted a 3D-printed triggerwheel. It's hold in palce by a 3D printed locknot and can be rotated to fit the TDC. Used small bolt heads to get the "metal" for the hallsensor that will be installed. Should be stirdy enough to keep the hall safley away, it have a pickup range of 5mm.



    Well kind of given up on the matching of old ecu with the speeduino, so the plan now is to use the triggerwheel to run the COPS with the speeduino and the carb. Get a newer generation 4AFE head port it a build a better flow intake then the one i have scramble. And the map and run it by the speeduino alone.
    Think i saves me alot of headacke.

    But i notic with the new engine mount i free up some cm behind the motor so i think about using the distributer base with the sensors as a cam angle sensor like you recomended jondee86 and then run fully sequential. That should work rigth?

    Now i just hope that i will get the COP's so i can try and mount them but im afraid that corona migth ruin the shipping.

  6. #21
    Junior Member Backyard Mechanic jondee86's Avatar
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    Default Re: Crank timing for COP 4AFE/7Afe

    Quote Originally Posted by Ceasar View Post
    But I notice with the new engine mount I free up some cm behind the motor so I think about
    using the distributor base with the sensors as a cam angle sensor like you recommended jondee86
    and then run fully sequential. That should work right?
    Probably need to clarify about sequential injection and ignition. Sequential offers very little performance gain over batch firing, and older Toyotas typically used batch firing for injection and a distributor for ignition. The distributor does actually achieve sequential ignition by its mechanical arrangement of firing each plug in turn, but the ECU itself is not capable of firing the plugs in order without the distributor.

    To obtain true sequential operation with COP's first you need both a crank position signal and a cam position signal. These signals can be obtained from the VR senors in the factory distributor base. Second you need an ECU capable of generating sequential outputs for both fuel and ignition. So basically an aftermarket ECU that has four separate injector outputs and four separate ignition outputs. Such an ECU will use the crank and cam position inputs to calculate the optimum point during the 720deg engine cycle that each injector and coil should be fired.

    With the factory ECU and the stock crank and cam inputs the best you can get will be the stock injector firing pattern and batch fired COP's.

    If you want to use a crank mounted trigger wheel and/or any combination of stock and non-stock sensors, you will need an aftermarket ECU. While a new ECU may not be in your budget right now, I would suggest that you look for anyone selling a new or used Megasquirt or similar that is capable of supporting full sequential, and see if you can buy it at a good price. There may even be someone in your country who can build you one

    Cheers... jondee86

  7. #22
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    Default Re: Crank timing for COP 4AFE/7Afe

    Ive been thinking about fitting a a 4AFE to RWD as well. The distributor cap and rotor from a toyota UZ engine fits on the cam pulley. it loks like it could be an easy mod
    https://www.ebay.com.au/itm/Toyota-S...YAAOSwqoheeYI-

    I cant get the photos to upload have a look at the link
    there is also a video of the rotors
    https://www.youtube.com/watch?v=us0UHJ1o6cU
    Last edited by Liquidhandwash; 08-04-2020 at 09:49 PM.

  8. #23
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    Default Re: Crank timing for COP 4AFE/7Afe

    Yeah i got that, but sequential injection have the benefit of a little bit more fuel efficient right?
    But ye i got mistaken that i could run sequential cops with just the crank sensor so was down and measured some more and by cutting the distributer by the 24 tooth wheel i will make it fit in the original spot! Do i need a missing teeth on the cam aswell?

    Yeah im decided to going fully stand alone ECU, the speeduino im been looking at have the ability to give 4 separate ignition and injection signals. Its surprisingly cheap and my friend that just turbo his M54 with a speeduino seem to got it working really well.
    But im doing a budget right now of all the parts i will need to get it working. A bit fun to learn how to map a car and have the ability to later move to force induction!

    Oh fun if you jumped onboard the train Liquid, tell me if you need any help with it! Havn't thought about using the UZ but yeah that would solve my 3D printed solution, i dont really get where the UZ sensor is reading, are they a triggerwheel on the pulley or is it counting the pulley theeth?
    I did tough shorten it down last time a was i the garage and moved it close to the cam pulley, its a bit more snug now.

    But yeah thread-wise i think i got all the answers handed to me and had to rethink a bit. But really a lot of thanks for the information jondee86 and Liquidhandwash i think i will move the continuing progress over to my build thread.

  9. #24
    Junior Member Backyard Mechanic jondee86's Avatar
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    Default Re: Crank timing for COP 4AFE/7Afe

    Yes, full sequential injection means that each injector is fired at the optimum moment, generally considered to be when the end of injection occurs just a few crank degrees before the inlet valve opens. This will give smoother running, better idling and greater efficiency. For COP's sequential firing reduces coil heating and gives more time for the coil to fully charge at high rpm.

    To run full sequential you will always need a crank sensor and a cam sensor. If you cut the 4-tooth wheel off the distributor then you will have to obtain a cam signal from somewhere else. With an aftermarket ECU you are not limited to the 4-tooth wheel, you can use a single tooth wheel or even place a sensor in the cam cover and read a cam lobe or a single tooth ring pressed onto the end of the cam. Most aftermarket ECU's will also accept Hall Effect and Optical sensor inputs.

    The missing tooth on a 36-1 crank trigger wheel acts as a reset but if you don't have a separate cam signal you can only run wasted spark. When you have a separate cam signal you can run sequential without having a missing tooth on the crank trigger wheel. Your distributor has 24 teeth for the crank signal and 4 teeth for the cam signal. Many aftermarket conversions grind three teeth off the cam trigger to provide a single tooth reset signal. Good luck

    Cheers... jondee86

  10. #25
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    Default Re: Crank timing for COP 4AFE/7Afe

    Hmm hello im back again!

    getting a bit restless in these quarantine so couldn't let the simple solution of using the arduino to power the cop that Liquid linked before.
    https://github.com/dalathegreat/Arduino-Coil-On-Plug
    And thought that if i can get it to work i migth benefit alot of people using the 4A paltform to convert to COP's.

    So i rebuilded the code a bit and sat up one arduino to fake the IGT signal of the engine aswell as a fake hallsensor signal. My plan was to locate 1 tooth inbetween 4:th and 1:th cylinder on the crank. So the hall sensor gives its signal before the firest cylinder fires. And it seems to work.

    After it syncs with that i will fire 1-2-3-4 and as the output says for every IGT signal, i will running batchfire.

    Like how Daniel did with the source code, i will solder mosfets so the IGT signal get to the arduino and also gets bypassed by the mosfet active to the right cylinder, after that the arduino turns the first mosfet off and primes the other mosfet and so on.

    I just wonder, the IGT signal, is it a 12v? in that case i have to build a step-down.
    And also i would need some help with risk analysis, with this setup what do you think can go wrong? not very tempted to blow my engine but very tempted to try it.
    What do you think?

    Code:
    const byte IGTPin = 2;   //Interrupt pin for IGT signal from ECU (pin3)
    const byte crankPin = 3;  //Interrupt pin for crankshaft reference pin (pin2)
    volatile boolean syncAchieved = 0;    //Set this to true if sync has been achieved
    volatile byte cylinderCounter = 0;    //Sequence which cylinder should fire (0-1-2-3)
    const byte fireOrder[] = {            //Table containing the fireorder (1-3-4-2)
      B00000001,                          // cylinder 1-4
      B00000010,                          // cylinder 2-3
      B00000001,                          // cylinder 1-4
      B00000010
    };                         // cylinder 2-3
    
    
    void setup() {
      Serial.begin(19200);               //for debug
      pinMode(crankPin, INPUT_PULLUP);   //Interrupt pin for crankshaft position Use pullup to get rid of dangerous wire break situation
      pinMode(IGTPin, INPUT_PULLUP);
      DDRB = 0b00000011;                 //Set the first 2 pins on the B register to outputs.
      attachInterrupt(digitalPinToInterrupt(crankPin), ISR0, RISING);
      Serial.println("Startup");
    }
    
    void loop() {
      // put your main code here, to run repeatedly:
      while (syncAchieved == 1) { //Start sequencing ignition outputs when sync has occured. Otherwise just wait until engine starts rotating.
        PORTB = fireOrder[cylinderCounter];
      }
    }
    
    void ISR0()
    {
      detachInterrupt(digitalPinToInterrupt(crankPin));              //If sync is achieved, we immedeatly disable keeping track of the position pin permanently
      syncAchieved = 1;                                              //Set variable used to start ignition and disable unnecessary measuring of position pin
      Serial.println("Sync Achieved");                               //Add when troubleshooting
      attachInterrupt(digitalPinToInterrupt(IGTPin), ISR1, HIGH);    //We no longer keep track of change state once synced. Now we locate rising change on the ref pin.
    }
    
    void ISR1()
    {
      if (syncAchieved == 1) {                                        //If we have achieved sync, do only this part of the interrupt
        if (digitalRead(IGTPin) == HIGH) {                        //This is an "unneeded if". It filters out spark EMI, incorrect pulses will be counted otherwise.
          cylinderCounter++;                                      //we sequence the next cylinder that should fire
          Serial.println(cylinderCounter);                        //debug line to see that the right cylinder are shooting
          if (cylinderCounter > 3) {
            cylinderCounter = 0; //This a reset for the cylinder firing sequencer. We have 4 cylinders, so we reset after we reached the final one.
          }
        }
      }
    }

  11. #26
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    Default Re: Crank timing for COP 4AFE/7Afe

    Good job on the coding, Im not great with that. IGT Signal
    Have a look at this it might help.
    https://www.toyotaguru.us/engine-con...gt-signal.html

    The primary coil current flow is controlled by the ECM through the Ignition Timing (IGT) signal. The IGT signal is a voltage signal that turns on/off the main transistor in the igniter. When IGT signal voltage drops to 0 volts, the transistor in the igniter turns off. When the current in the primary coil is turned off, the rapidly collapsing magnetic field induces a high voltage in the secondary coil. If the voltage is high enough to overcome the resistance in the secondary circuit, there will be a spark at the spark plug.

  12. #27
    Junior Member Backyard Mechanic jondee86's Avatar
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    Default Re: Crank timing for COP 4AFE/7Afe

    The IGt is a 5V signal suitable for directly controlling COP's with built-in igniters or external OEM igniters. Basically it can only control a transistor that switches the 12V to the coil on and off. Over to you of course, but if you are going to batch fire the COP's you can do that by sending the IGt signal from the factory ECU to all four COP's as per the diagram on Page 1 of this post

    Cheers... jondee86

  13. #28
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    Default Re: Crank timing for COP 4AFE/7Afe

    I just watch a video of these guys fitting LS1 coils to a Mitsubishi they drilled a hole in the cam pully and fitted a bolt to it than use a hall effect sensor as a reset. https://www.youtube.com/watch?v=HU6fYB54T60
    Which got me thinking if you coded the Arduino to input the factory ECU tach signal, and output a signal to four pins (let's say pins 4567) in a sequence, the Hall effect sensor would reset the sequence to the start.
    The dwell time and advance would then be the same as the factory. As I said before im a crap coder I keep getting errors Maybe you will have better luck

  14. #29
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    Default Re: Crank timing for COP 4AFE/7Afe

    Also have a look at this video, his code almost does what we want just need to add 3 leds and an add 3 outputs https://www.youtube.com/watch?v=C_w79mtOAzg

  15. #30
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    Default Re: Crank timing for COP 4AFE/7Afe

    Sorry for slow response! been busy with life

    some fun news is that i bought a 7AFE now to put in my car!

    The ignition project havn't been making any progress tough cant seem to make the signal to go high when it should to let the IGT signal pass..

    jondee86 so yeah it seems like i have to go with that solution to start with at least. One thought, the 20v 4age have squential injection but the 7afe have batch? Would the ignition of all 4 coils then have a chance to ignite the wrong cylinder or should it be safe?

    Liquidhandwash, the tach signal is not a bad idea! im afraid it just adds 4 pulses so it would be a problem to know what pulse is cylinder one to sync with? if you understand what i mean.
    Interesting video, he seem to do quite the same so will try to change my code some.

    //thanks and cheers!

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