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AngelPowy

Z20let timing drift

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Hi, I am currently working to mount a G4+ xtreme black ecu on a Z20let engine with stock Crank sensor. But I have lot of timing drift on the car. when I do calibrate with timing locked to 10*, It's ok at 1000 RPM it go to 0* at 2000 RPM -10 at 3000 and so on.. As the sensor is a vr one, I thought about polarity and I tried in both polarity but it does not seems to solve the matter. Do you have some idea of what goes wrong?

 

Best Regards

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17 hours ago, Adamw said:

I dont think I have even seen a Z20 for about 20years...

LOL, I was assuming a Nissan Z20...   I just realised Vaxhual have a Z20 too, which is probably what you are talking about..

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Thanks for the scope pic.  That looks ok.  Crank sensor wiring is correct.  

Since the rising and falling edge of trig 2 is close to the gap that can potentially be an issue.  I would try setting sync mode to "Cam Level" in this case (offset may need changing by 360 if it wont start after that change).

The picture of the coil doesnt help much and I cant find much info on it.  How sure are you that it does have built-in ignitors?

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Thank you for this answer. I assue you are dealing with trigger 2 sync mode and it's already on "cam level". And yes I Do think that it has buil-in-ignitors. I give you a pic of the coil stock signal at idle if it can provide you some information. 5V/div and 1ms/div

Allumage.PNG

Ps: Additionnal Info on the coil there is 6 pin +12v and ground and 4 signal.

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Yes, that signal shows there is no ignitor in the coil - I suspect the factory ECU must have the ignitor inside as this waveform shown appears to be an "ignition primary" wave form.  Notice it initially sits at 13V, then drops to 0V, for about 3ms (dwell), then sharply rises to ~40V for the spark.  If there were ignitors in the coils this waveform would be upside down, it would only be 0-5V or 0-12V and there would be no reflection or "ringing" from the spark.

So yes, you will need to add an ignitor or change to coils with ignitors built in.

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Ok If I correctly understand you actually coilpack is wiring wrong and I should add an external ignitor between the ecu and the coilpack. But how did car firing till now? And can this low voltage coil driving cause this delay ( much effort to produce spark maybe?)

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16 hours ago, AngelPowy said:

Ok If I correctly understand you actually coilpack is wiring wrong and I should add an external ignitor between the ecu and the coilpack.

Correct.

 

16 hours ago, AngelPowy said:

But how did car firing till now?

Sometimes they will work without an ignitor but you will have a very weak spark (and extreme timing drift).

 

16 hours ago, AngelPowy said:

And can this low voltage coil driving cause this delay ( much effort to produce spark maybe?)

Your coil expects a falling signal to tell it to start charging (start of dwell), then will spark on the rising edge.   A coil with built in ignitors is opposite to this - it starts charging on a rising edge then sparks on a falling edge.

So without an ignitor and the ECU set to falling spark edge your coil is actually firing at the start of the dwell time (say about 3ms earlier than the ecu thinks).  3ms is not much angular timing error at low RPM, but as RPM increases, 3ms becomes quite a big angular error.  This is where your "drift" comes from.

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Hi, first of all Merry Christmas to you. Let me thank you twice for your precious help. I did not suspect coil at any time. We are going to order the external ignitor to finish our standalone ECU setup. Do you have a preferred external ignitor or I can take whatever I want?

Best Regards Guillaume

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16 hours ago, AngelPowy said:

Hi, first of all Merry Christmas to you. Let me thank you twice for your precious help. I did not suspect coil at any time. We are going to order the external ignitor to finish our standalone ECU setup. Do you have a preferred external ignitor or I can take whatever I want?

Best Regards Guillaume

I always use the bosch ignitors, or the link ecu items, wich are infact the same units ... only good results with it

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Spark edge should be set to falling when using a conventional ignitor, the “signal” gets inverted by the ignitor so the coil sees the opposite.  Wiring sounds correct.  Note you will need to check base timing again as it will probably move a bit.

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Ok so my spark edge was wrong. I did base timing again on the car but 2 output was not working so car did not run well. Finally i did wiring it wrong ( without external igniter again) i lowered dwell to 0,4ms and no more timing drift. But how bad this erratic wiing is nefast for the Ecu?

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