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Ignition Timing for RB25DET Manual with Auto ECU

wadedos

By wadedos,
in Engines & Forced Induction

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wadedos Apprentice

wadedos

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Ignition Timing for RB25DET Manual with Auto ECU

I have a 1996 ECR33 GTS25T RB25DET which was a factory automatic. It has been converted to a manual but still has the auto ECU. The previous owner had apparently removed the CAS to supposedly check the cambelt, then installed it centre. Now my question is for you guys, is what is the actual base timing degree to set ? I have read that is supposed to be 10*,15*,20* for an auto ?

So what is the actual base ignition timing degree value to set for an auto ECU or is the same as the manual ECU ?

Thanks in advance :)

GTSBoy Grand Master

GTSBoy

Posted
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Autos are set at 20°.  Manuals are set at 15°.  You can idle a manual at the auto ECU's 20° if you like.  But if you want to finish "manualising" it, back off the CAS 5° and the ECU should still hit all the ignition timing numbers in the map when you're off idle, so there is no problem.

wadedos Apprentice

wadedos

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Cheers mate, I wasn't too sure. 

I have tried both 15° and 20°. When I had set the timing to 20°, it idled way better and crackled and popped when decelerating. But when flooring it, the turbo over boosted hard ? Like was hitting 9 - 10 psi at 5k+ RPM 
Then setting it back to 15 ° it would run better and hold the boost defined my by blitz sbc. But idled quite rough.

Is this normal for it to over boost when running 20° ?

GTSBoy Grand Master

GTSBoy

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Actually, I just realised I told you a silliness in my first reply.

The ECU has no way of knowing that the base timing as set at the CAS is any one number or another.  So the manual ECUs expect it to be at 15°, and all the timing numbers in the maps are used as if it is set to 15°.  If you were to set it to 20° (at the CAS) on a manual ECU, then every timing point in the map will be 5° advanced.  Under these circumstances, it could well ping in the max torque rev range, which bashes the exhaust temperatures through the roof and it may well overboost.

In your case though, you have an auto ECU, and it fully expects the timing to be set to 20° at the CAS.  If you set it to 15° then it will be running 5° retarded everywhere.  This will be safe and boring.

The real question here though is.....what do you mean by "overboost hard".  9-10 psi is not very high, and if you have an EBC controlling boost, then you'd expect to be running 10 psi (being the sensible max on an R33 ECU).  There's no point having an EBC and trying to run the stock 7 psi.  So what exactly was it that you meant?

wadedos Apprentice

wadedos

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My ECU is 23710-13U10. Which is an auto ? 

Over boost hard I mean by setting 7 PSI for the low setting on my EBC, it spikes to 9 to 10 PSI. Which is almost 3 PSI difference. I even tried connecting the wastegate actuator straight to the vacuum line and still over boosted.

With the timing set the 15, this never happens.

wadedos Apprentice

wadedos

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Yeah I know. I'm a bit unsure, and confused. It's just really odd.

I have just set it to 15 at the moment. 
Is this going to seriously retard it ? It actually seems like it pulls harder and sharper on 15, compared to 20.

How would I know if its pinging or detonating ? would it be audible ?

I have a Power FC with Hand controller, just haven't put it in as I would need to get it tuned, which seems a bit pointless with the stock injectors and turbo. Need to upgrade.

wadedos Apprentice

wadedos

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There is no problem with 9 - 10 PSI. I just cant understand when its set to 15. It will only boost to the desired set level perfectly. When set to 20, it just completely overshoots the set level around 4.5K. It would actually probably keep boosting past 9 - 10 PSI, but I will take my foot of as it starts to break up pretty quickly.

Sound to me like its missing ? Like it popping and cant boost any more. 
The missing problem is another problem for another thread.

wadedos Apprentice

wadedos

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I don't think the misfire and pop is anything to do with the timing, as at 15* on 9 to 10 PSI it still does it.

Just on 20* it overboosts way past the set boost. So I cant even floor the car to red line.

It will idle at 650 at 15* but hunts a wee bit. If I raise the idle, it is abit smoother. But the car is so loud. So I prefer it lower.

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