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Alex182

rb25 no spark

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Hi,

last night we've been continuing tuning our rb25. Car idled the engine with no issues. Once we've turned it off, it didn't start anymore. No spark on all cylinders.

We've checked crank signal and got rpm in the link, checked the cas with oscilloscope, all fine with 0,5-4.2v signal. Then we've turned on the ignition test mode and the relais were clicking.
All Coils got 12v and ground. But in the coil connector we can only read 0,15-0,2volt on the signal wire. 

Any ideas what could cause this? Already tried older revisions and even the standard base map to ensure it's not based on any ecu configs.

Thanks!
Alex

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Hi Alex,

Which ignition coils are you using on the engine? Do they have built in igniters?

What is the dwell time the ECU is applying when you are cranking the engine?

Are the injectors pulsing when you crank the engine?

Scott.

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Hi Scott,

attached you can find my dwell table. We're using the oem rb25 Neo coils. Have already tried another set, same issue. Have tested resistency on all of them. Only potential issue we've found are the 0,2volt at the signal wire for the coils. Don't know how much voltage it should provide coming from the ecu.
Injectors are pulsing and we've tried old map revisions where it was definately working.

Many thanks in advance!
Alex
 

dwell.JPG

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Hi Alex,

The ECU's ignition outputs should drive high to 5V. If the ignition test function is causing the coils to fire then you could use your oscilloscope to check the ignition outputs of the ECU. If all is as expected you could then scope the ignition outputs during cranking and compare the signal to what you saw during the ignition test.

If you want to record a PCLog of you trying to start the engine and send it to me along with your base-map I will take a look. Either post here to the forum or email to tech@linkecu.com.

Scott.

 

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Hi Alex,

Thanks for the files. Looking through the base-map and the log files the only thing I noticed was that with the engine not rotating the MAP is reading 90 kPa. I see that your MAP sensor is configured as 'GM 3 bar', have you replaced the MAP sensor? If yes then the calibration may need adjusting. Regardless, this will not be the cause of no spark for you. I'll ask Simon (also on technical support) to take a look at your files and see if he has any ideas.

Scott.

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Log wise I also notice the map is reading low, assuming you are not at high altitude.

But this wont stop the coils firing.

I would check the resistance of the coil between the power supply wire and the signal wire. Can you let us know what you measure.

 

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Log wise I also notice the map is reading low, assuming you are not at high altitude.

But this wont stop the coils firing.

I would check the resistance of the coil between the power supply wire and the signal wire. Can you let us know what you measure.

 

Hi,

we've already chenged coils with those of another rb25.
The resistances you asked for:
~2,6 Ohm on all 6.

Tonight we'll switch ECUs and plug in an OEM one with Nistune board in it.
Let's see what it does.

BR
Alex

Edited by Alex182

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A resistance of 2.6Ohm is too low for a coil with a built in igniter.

A coil with an igniter built in will be reading in the K Ohms range minimum

2.6 ohms will be trying to draw over 4.5 amps at ~12V the ECU drive can only support 2amps max.

You can also check the ECU output with no coils connected using a test LED.

 

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Ground to 12v is 1,5kOhm, I meant ground to signal if I remember right.

But we've found the Issue, It's been a second 10A fuse we didn't know to be relevant for the ignition...

Sorry guys and many thanks!

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Sorry to bring out this old thread.  This is the dwell time fm Haltech(i think).  Shouldnt r34 gtr neo rb25 dwell increae that much.  Im asking bcoz the one i tune seems to have problem at silghtly higher boost.  Current dwell in base mao is fine at 0.8. But not stable miss any over 1.0bar. All new splitfire coils,  loom,  sparkes.

 

Tks

97E9C8D7-2544-4710-BC7A-0CD408D695F3.jpeg.d10ab33171d73080d9cef2f1c3781f1b.jpeg

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It comes down to the coil as to what the needed dwell is going to be. I would assume that table is for stock coils. 

If the dwell is too short you loose spark energy. If it is too long you risk overheating the coils.

 

I would try increased dwell time and see if it improves. While keeping an eye on the coil temps.

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