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Discussion Starter · #1 ·
Looking for a little advice, I am building a Ford 5.4 DOHC mod motor with a 6-71 supercharger. I am using an EDIS 8 setup with a Microsquirt configured for control of ignition and EFI. I am just getting this combo running and solving some problems. The first is a kicking back/backfire issue when cranking the motor, the setup right now is basic configuration of the Microsquirt so I am assuming the timing displayed in the TunerStudio of 10 degrees BTDC is accurate. It is acting like that 10 degrees is too much advance and is firing too early, I know this value can be adjusted using the software but I wanted to get some feedback before making any changes. I have reduced the cranking advance to 3 degrees BTDC and it is still kicking back against the starter. My cranking speed is a little low at 145 rpm. Roots superchargers do not like backfire so I need to solve this issue before I move on.
I do have a video of the backfiring if that will help. Once it starts it seems to run fine.
 

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It's better to be a Pennypacker, than a penny-pincher!
Seriously though, sounds like the computer is having problems figuring out where it's at. Also, you have come to the right place! I'm not the one to answer your question, but I'm sure someone here can help you. Soon!
 

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Put a timing light on it. Mark the balancer . 5 10 15 20 btdc. Then check it.The ECM may be giving 10 degrees , but it also depends where the trigger is oriented at on the crank.

Did the directions show where to mount?
 

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Discussion Starter · #4 ·
The crank trigger is a factory component, 10 degrees BTDC is the default EDIS advance (it uses that for limp-home mode) I can use the Microsquirt to change the advance, the problem with a timing light is that it is a wasted spark style ignition and difficult to see. It is also a cranking issue not a running issue, the motor runs fine once it starts,
 

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With the factory PCM, During engine crank the PCM will fire two spark plugs simultaneously. Of the two plugs simultaneously fired one will be under compression the other will be on the exhaust stroke. Both plugs will fire until camshaft position is identified by a successful camshaft position sensor signal. Once camshaft position is identified only the cylinder under compression will be fired.
Might be the issue. Can you disable injector pulse until the cam sensor comes online?
Is it set on batch fire or sequential (injectors).?
 

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Have you tried lowering the value of the startup rpm?
    • RPM: This is the rpm at which your MicroSquirt® controller switches from the cranking pulse width injected at every ignition event to the pulse width calculated from the fueling equations (MAP, IAT, RPM, etc.). 300 rpm is good for most automotive engines, but a higher value may be needed for motorcycle engine or other specialized uses.
 

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The crank trigger is a factory component,
Not sure if the factory unit is aligned correctly for the Squirt. This is from the manual explaining how to check with a timing light.
(I also noted that the "missing tooth" on the crank trigger is what is used for cam Sensor calculation ...duh)

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. Note that at very low rpms (less than 400) the EDIS with no SAW input will start at almost TDC and as rpm increases towards 400 the ignition point will approach 10° BTDC; it will be stable above that engine speed. So the engine must be running to check the timing, cranking won't work. 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.
 

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Discussion Starter · #9 ·
I can adjust the spark advance using the TunerStudio, what do you think would be a good cranking advance amount?
The EDIS does not use a cam sensor, it is based entirely on a crank sensor.
My timing should be factory perfect as I am using the original factory timing wheel and sensor.
I did reduce the cranking speed via the TunerStudio but I keep thinking that it should be cranking faster than 145 rpm.
 

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Discussion Starter · #11 ·
No, it is the speed the Microsquirt uses to distigush between starting and running. Once it goes over that value it switches to engine warm up mode as far as ignition curve and fuel map. I was just wondering if this low value (my engines cranking speed) might be the cause of the kickback. I am still using a temporary setup with the battery and cables.
 

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They refered to it as the startup RPM.. But yes ,it is the engine speed setting that is the threshold between pre determined injector pulse and the transition to calculated pulse width by using sensor data.
 

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Have you tried lowering the value of the startup rpm?
    • RPM: This is the rpm at which your MicroSquirt® controller switches from the cranking pulse width injected at every ignition event to the pulse width calculated from the fueling equations (MAP, IAT, RPM, etc.). 300 rpm is good for most automotive engines, but a higher value may be needed for motorcycle engine or other specialized uses.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

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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. Note that at very low rpms (less than 400) the EDIS with no SAW input will start at almost TDC and as rpm increases towards 400 the ignition point will approach 10° BTDC; it will be stable above that engine speed. So the engine must be running to check the timing, cranking won't work. 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.

Here is how to verify the crank (VR) sensor postition. ^^^^^^^^^^

I know you are using the factory setup. How do you know that is where micrsquirt wants it? I am looking for the spec
 

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Discussion Starter · #16 ·
The Tunerstudio actually has a setting specifically for the EDIS (they are very popular in Europe)

The TunerStudio displays the correct 10 degrees when the engine is cranking, as soon as the engine starts the ignition map steps in and advances the timing to 20 degrees (which is the recommended advance for this motor supercharged)
 

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OK. I see the spec.The microsquirt wants the missing tooth at 50 degrees BTDC. Since the trigger is on the crank inside the engine , we can safely assume the the PIP signal is correctly timed. Ignition timing from the microsquirt sounds correct for startup as well, in that case.

My concern was that you may have some advance built in where the crank sensor is located, but now I see the factory location is 50 dgrees BTDC , and thats what the setup wants , so that is a non issue

Could the misfire be a defective coil by chance. You know, an open in the primary side of a coil will cause a misfire / backfire. Just a thought.
 

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Also saw this.

Cranking Trigger is used to determine when to fire the spark plugs between 50 and 300 rpm (by default) The cranking trigger can be calculated, trigger return, or trigger rise.:


  1. Calculated: this means that your MicroSquirt® controller fires the spark the same way it does when it is above the cranking rpm (CRANK_RPM, default is 300 rpm). That is, it makes a prediction of when the next tach pulse will arrive, based on the previous pulse times, and sets timing based on this and the values in the spark table. If the starting tach pulses are erratic or noisy, this can make the spark timing erratic, resulting in poor cranking behavior. However, some ignition setups require the use of the 'calculated' parameter. For the most part these are with multi-tooth wheels and the timing error is limited to the gap between teeth at an absolute maximum (usually much less), and thus erratic cranking timing isn't a problem.
  2. Trigger Return: The crankshaft speed varies quite a bit at cranking speeds. It is affected by the compression and power strokes more than it would be during normal running. This makes it difficult to predict when the next TDC will occur from the last TDC event. As a result, some OEMs have devised a 'trigger return' wheel. This is a wheel with broad teeth, such that during cranking the spark is fired on one edge of the tooth with no computer advance, only the advance set by the width of the tooth edge; when rpm goes above cranking, it switches to firing on the opposite edge of the tooth with calculated advance. This edge typically has a smaller built in advance, possibly 0°. This latter advance should be what is entered in the trigger offset. This option should NOT be selected unless you have a trigger wheel made for this purpose and understand how it is set up.
  3. Trigger Rise: is the best all around selection for most installations. It fires the spark plugs when the 'normal' trigger is seen (i.e., the signal that comes at the trigger offset). Use this if it you are able to set up your tach input to your MicroSquirt® controller so that it comes in at a good timing advance for starting, generally something like 5-12° BTDC. Then your MicroSquirt® controller will fire the spark at the exact instant the trigger signal comes in and you will have consistent advance during cranking (at the trigger offset), no matter how uneven the engine speed.
Maybe you should adjust this setting. Number 3 sounds like a good start. Number 2 may be relevant as your application is supercharged. That could be wacking crankshaft velocity around a bit.
 
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