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KristiangTuner

Dwell time and burned coils

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Hi guys.

Im been having issues with a car i installed a G4 Atom in.

The car had a stock ignitor module with stock coils. First during tuning i got spark issues, turned out a coil was half dead. Replaced it and kept going, than the ignitor died.. replaced it. Got spark blowout issues at boost. Decided to bypass ignitor and run controllable coils. that helped alot , but again got spark blowout issues at higher boost (running 2ms dwell flat) , tried to go to 2.5ms at boost and gap the plugs far down, helped a while but then burned a coil. Replaced that coil and was able to finish the tuning job (500nm/350whp at 22psi). Then at final road/cruise tuning a coil fried again.

I logged dwell time and i see some major peaks in dwell , dwell table was set from 1.8ms at idle to 2.2ms at full boost. In the midrange rpm/boost there is some sudden peaks in logged dwell jumping from 2ms to 20-35ms!!

What can be causing this and could it be the reason for the spark issues?

I installed stock ignitor and coils and the car blow spark at 12psi...and this is a know setup to me so normally that stock setup should handle at least 17psi

Customer will atempt to wire new +/- leads to the coils to ensure they get enough power and that there isnt a weak connection etc leading to voltage drop during high duty.

But this strange dwell time peaks in the log worries me.

 

Edited by KristiangTuner

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I logged dwell time and i see some major peaks in dwell , dwell table was set from 1.8ms at idle to 2.2ms at full boost. In the midrange rpm/boost there is some sudden peaks in logged dwell jumping from 2ms to 20-35ms!!

This is called "dwell scatter", it is normally a symptom of a trigger error/loss of engine position.  You need to be careful when this is present as it probably means there are sparks happening at random times also so potential for engine damage is higher.

Can you tell us more about the engine, what it has for triggers etc.  

Do you have access to an oscilloscope or perhaps you can borrow another G4+ that has the built in trigger scope?  

 

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I thought so as well, and this is a nissan CA18DET running 24+1 disc on cam with stock opto, but i dont think its signal then, more likely noise interference.

I checked timing all the way to the limiter without load to set timing delay and i didnt visually see any scatter with the lamp, but of course the lamp wont always be able to show that.

I piggybacked the ECU on stock harness but ran the Link trigger cables with proper screen all the way to the sensor.

Im working on new power supply and ground to the coils to make sure thats ok.

Might be bad coils, both for ignition issue and noise reason. I only worked with old stock coils on it.(dum CA18 coils and smart RB25_s2 coils)

Gonna try new power wiring and some new aftermarket coils and see.

Tune job done with proper knock detection and no obvious starange issues related to the rpm range that had the dwell scatter.

I was able to finish tuning the car when i ran those RB25 coils with higher dwell time, was just finalizing crusing before i was to take the car off the dyno when one of those coils died from overheating. I then had to put the stock ignitor and coils back in and bring the boost down from 1.6bar to 0.7 to avoid spark blowout.

Edited by KristiangTuner

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