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 Post subject: Diagnose this Misfire
PostPosted: Fri May 18, 2018 10:27 am 
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Joined: Thu Jul 28, 2011 4:10 am
Posts: 812
ECU Model: S100 Pro
My K series Elise started misfiring as in bap bap bap at a regular frequency at bang on 4000 rpm, it would drive through it and then clear up and run just fine until you hit 4000 again.
Set up as follows.
Sequential on, using injection angle map and had been running fine before this started.
Issue disappears when in batch injection mode
Nothing special on the crank or cam errors, perhaps 30 cam errors after 5 trips
Starting fine.
Worse at full throttle than part.
Not a wiring fault or interference
Crank scope fine even when misfiring
Launch, traction and shift cut all off in SW
I recently changed to larger injectors
Lambda working ok
Nothing of interest in the logs

I found the issue last night and thought this would be good for a bit of armchair diagnostics :)


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 Post subject: Re: Diagnose this Misfire
PostPosted: Fri May 18, 2018 10:53 am 
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Joined: Tue Jan 16, 2018 9:38 am
Posts: 31
Location: Aberdeen
ECU Model: S100 Pro
Distributor: DTA
What's the coil dwell like? Could it be just marginal when in non-sequential, then showing it's limitation when in sequential?
Only other thing I can think of - some sort of interference thats only there on sequential?


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 Post subject: Re: Diagnose this Misfire
PostPosted: Fri May 18, 2018 11:28 am 
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Joined: Thu Jul 28, 2011 4:10 am
Posts: 812
ECU Model: S100 Pro
No, dwell unchanged as I still use the same double end wasted spark coils, so only sequential fuel not spark.
Not interference and cam and crank scope fine.

Keep trying :)


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 Post subject: Re: Diagnose this Misfire
PostPosted: Fri May 18, 2018 12:42 pm 
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Joined: Tue Jan 16, 2018 9:38 am
Posts: 31
Location: Aberdeen
ECU Model: S100 Pro
Distributor: DTA
If nothing else has changed bar the larger injectors, perhaps something to do with fuel pressure? do you run double injectors - is the change-over point at 4k?

I'm stumped! Any clues? / hints?


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 Post subject: Re: Diagnose this Misfire
PostPosted: Fri May 18, 2018 12:54 pm 
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Joined: Fri Feb 28, 2014 1:03 pm
Posts: 1026
ECU Model: S40 Pro
Distributor: DTA
Firmware Version: 79
If it runs fine in batch injection, it's something to do with the injection.
I can't think of anything that's RPM related in sequential injection, so that points to the injector angle map.

No idea what though.


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 Post subject: Re: Diagnose this Misfire
PostPosted: Fri May 18, 2018 2:08 pm 
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Joined: Tue Aug 02, 2011 12:08 pm
Posts: 2850
Location: Norn Iron
ECU Model: No ECU
Is 30 cam errors not a lot ?

Why do you mention a recent change to larger injectors ? How recent ?

And is not uploading the map a clue that it was a config problem ? lol

Whether IDT or Inj timing as Alex suggests.


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 Post subject: Re: Diagnose this Misfire
PostPosted: Sat May 19, 2018 4:47 am 
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Joined: Fri Feb 28, 2014 1:03 pm
Posts: 1026
ECU Model: S40 Pro
Distributor: DTA
Firmware Version: 79
30 cam errors is nothing. You'll usually get one or two on start up


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 Post subject: Re: Diagnose this Misfire
PostPosted: Sun May 20, 2018 2:50 am 
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Joined: Thu Jul 28, 2011 4:10 am
Posts: 812
ECU Model: S100 Pro
See Alex is the man and I only stumbled on the problem. The injection angle map had become corrupted somehow. the map had the -prefix missing from 4000rpm onwards so it was jumping from -270 deg to +270 in an instant therefore missing a complete power cycle. hope this map corruption thing is just a one off


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 Post subject: Re: Diagnose this Misfire
PostPosted: Sun May 20, 2018 11:22 am 
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Joined: Tue Jan 16, 2018 9:38 am
Posts: 31
Location: Aberdeen
ECU Model: S100 Pro
Distributor: DTA
Well sussed!

I have another strange one;

I use the "Pit lane speed limiter" set to RPM as a limiter for tyre warming (Otherwsie I always seem to hit my soft limiter as the engine revs up so fast).

If I'm in the paddle shift window, if I try to change any parameter, I get a warning along the lines of "pit lane limiter already in use". Before I can F4 any changes on the paddle window, I have to disable and F4 the pit lane limiter and then go back and F4 the paddle window, and then switch the pit lane limiter back on. Strange as I'm not using that input for anything else?


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 Post subject: Re: Diagnose this Misfire
PostPosted: Mon May 21, 2018 3:02 am 
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Joined: Fri Feb 28, 2014 1:03 pm
Posts: 1026
ECU Model: S40 Pro
Distributor: DTA
Firmware Version: 79
Steve, that's a bug in the software.
I'll fix that shortly.

Rob, that's unlikely to be corruption, but more likely a bug in the upload/download somewhere.
Please can you send me an email with a correct map, as well as either an incorrect map, or a description of where the minuses went missing?


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