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Author Topic: Check engine light  (Read 3796 times)
suzyj
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« on: June 14, 2013, 05:28:20 PM »
So I've got my bike (somewhat modded 695) going with a new custom loom. There's one loom screwup, where I transposed the side stand and clutch connectors, which is easy to rectify. All the gauges and controls work nicely. The engine runs nicely (like a demon), I've got gobs of power and (thanks to the DP ecu) it doesn't appear to be running lean any more. I've connected ducati diag to it, and thus far all looks extremely happy. All the displayed values (battery volts, air temp, pressure, oil temp, tachometer, etc) look sane, and even the TPS came up spot on.

Except.

My check engine light stays on. I'm perplexed. I can't find anything in ducati diag to turn it off, or that's telling me its on, for that matter. I'm getting pretty close to disabling the light with a pair of sidecutters.

What exactly does the check engine light tell me anyway? I mean if one of the sensors (crank, tps, air) wasn't reading right, it'd be pretty obvious. Similarly if an injector or coil isn't firing, that's pretty obvious too.
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2007 Monster 695 with a few mods.
2013 Piaggio Typhoon 50 2 stroke speed demon.
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« Reply #1 on: June 14, 2013, 09:58:09 PM »
If you get no trouble codes (assuming Ducati Diag works as claimed) I would think back feed through ground from another circuit. 
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suzyj
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« Reply #2 on: June 15, 2013, 01:27:00 AM »
Learning to drive ducatidiag helped.

Turns out the ecu is too smart for its own good. It was upset because the fuel pump relay isn't drawing any current. Given that I don't have a fuel pump relay, that's reasonable. A 470 ohm resistor between the fuel pump relay output and +12v shut it up Smiley
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2007 Monster 695 with a few mods.
2013 Piaggio Typhoon 50 2 stroke speed demon.
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« Reply #3 on: June 15, 2013, 02:25:19 AM »
What??

An engine management fault suzyj doesn't know how to fix? 

Really??

Oh wait....
Quote from: suzyj on June 15, 2013, 01:27:00 AM
Learning to drive ducatidiag helped.

Turns out the ecu is too smart for its own good. It was upset because the fuel pump relay isn't drawing any current. Given that I don't have a fuel pump relay, that's reasonable. A 470 ohm resistor between the fuel pump relay output and +12v shut it up Smiley
Nope.

Not really  waytogo.
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« Reply #4 on: June 15, 2013, 04:45:58 AM »
Great detective work!
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ducpainter
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« Reply #5 on: June 15, 2013, 04:56:19 AM »
Quote from: suzyj on June 15, 2013, 01:27:00 AM
Learning to drive ducatidiag helped.

Turns out the ecu is too smart for its own good. It was upset because the fuel pump relay isn't drawing any current. Given that I don't have a fuel pump relay, that's reasonable. A 470 ohm resistor between the fuel pump relay output and +12v shut it up Smiley
Why did you decide to not run a pump relay?
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suzyj
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« Reply #6 on: June 15, 2013, 05:05:54 AM »
Quote from: ducpainter on June 15, 2013, 04:56:19 AM
Why did you decide to not run a pump relay?

I don't have any relays. I do the fuel pump drive and headlight with power MOSFETs. The circuit driving them has relatively high impedance (compared to relay coils, anyway).
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2007 Monster 695 with a few mods.
2013 Piaggio Typhoon 50 2 stroke speed demon.
ducpainter
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« Reply #7 on: June 15, 2013, 05:26:09 AM »
Quote from: suzyj on June 15, 2013, 05:05:54 AM
I don't have any relays. I do the fuel pump drive and headlight with power MOSFETs. The circuit driving them has relatively high impedance (compared to relay coils, anyway).
Can you use one of those for the starter also?

Keep in mind I only know enough about electricity to incompetently free the smoke. Grin
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"Once you accept that a child on the autistic spectrum experiences the world in
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suzyj
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« Reply #8 on: June 15, 2013, 05:20:14 PM »
Quote from: ducpainter on June 15, 2013, 05:26:09 AM
Can you use one of those for the starter also?

Keep in mind I only know enough about electricity to incompetently free the smoke. Grin

I toyed with doing a MOSFET starter contactor. Indeed I have a design for one using four IRF3006 power MOSFETs in parallel. thats oodles to supply the 120 odd A that the starter draws. What stopped me from doing it was more not really knowing what the back-emf from the starter would do when it switched off.

I am buffering the input to the standard contactor tho, which has completely cured my original electrical issue of occasionally not starting.
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2007 Monster 695 with a few mods.
2013 Piaggio Typhoon 50 2 stroke speed demon.
ducpainter
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« Reply #9 on: June 16, 2013, 04:32:06 AM »
Quote from: suzyj on June 15, 2013, 05:20:14 PM
I toyed with doing a MOSFET starter contactor. Indeed I have a design for one using four IRF3006 power MOSFETs in parallel. thats oodles to supply the 120 odd A that the starter draws. What stopped me from doing it was more not really knowing what the back-emf from the starter would do when it switched off.

I am buffering the input to the standard contactor tho, which has completely cured my original electrical issue of occasionally not starting.
Does the back-emf result from the starter acting like a generator when spinning on over-run?
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"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent.”
suzyj
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« Reply #10 on: June 16, 2013, 12:05:20 PM »
It's actually from the inductance in the starter motor windings. When you suddenly try to interrupt the current, the winding inductance generates a large negative voltage to try to keep current flowing. On a mechanical contactor it causes arcing across the contacts. On a transistor switch the large negative voltage can cause destructive breakdown and let the smoke out.
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2007 Monster 695 with a few mods.
2013 Piaggio Typhoon 50 2 stroke speed demon.
ducpainter
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« Reply #11 on: June 16, 2013, 12:32:10 PM »
Now the smoke is coming from my ears.  Tongue
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"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent.”
Duc796canada
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« Reply #12 on: August 24, 2013, 07:20:34 PM »
Can you do the same diode bridge across for the back EMF in your set up?
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