R400D: Curious misfire

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Jonathan Kay
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Would that be in any of the Caterham factory wiring diagrams?

Jonathan

John Vine
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Well, sort of, Jonathan (and a good suggestion).  My own Assembly Guide includes a wiring diagram for the ECU with wire references (such as NW58 on Pin 36 ending up on coil #1).  But it's a royal pain to trace them all, made worse by the poor print quality of the diagram.

What I'd really like is the 992 equivalent of this 9A4 list. Of course, it could be that the 992 pinouts are the same anyway!

JV

Jonathan Kay
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"What I'd really like is the 992 equivalent of this 9A4 list(link is external). Of course, it could be that the 992 pinouts are the same anyway!"

Is James suggesting here that they are the same, or only the pins used for CAN?

https://www.caterhamlotus7.club/comment/2112434#comment-2112434

Jonathan

aerobod
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Hi John,

Pinouts for 9A4 and 992 are the same, but function on pins 16,17,19,25,27,33 & 34 can vary as those pins are all programmable using Easimap.

When I swapped my 992 for a 9A4 I didn't do any repinning, but I did add an additional wire in Pin 28 for Baro sensor function initially with the 992 which then showed the right value in Easimap, it just didn't do anything with it due to the locked Caterham map.

James

John Vine
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Thanks, James.

JV

John Vine
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Time for an update...

I'm pleased to say that, with Easimap's help, the problem is now 100% solved.  It was the lambda O2 sensor, aided and abetted (maybe) by a corroded connector.

So, the prize goes to...

Olly Amos (Amos91) in post #3. Thumb Up

 

A couple of days ago, I recorded an in-flight Easimap log of around 45 mins.  This is a snapshot:

The blue trace is Lambda voltage (left axis), and the brown trace is engine speed.

Note the long spells where no sensor activity is apparent.  During these spells, the engine cut out completely.  The spikes in engine speed are when I dipped the clutch and revved briefly after one of these cuts (the peaks are 5770 and 5990).  The car was becoming all but undriveable.

Back home, I removed the sensor and inspected the wiring and connector.  The wiring was sound but the connector terminals were badly corroded:

I cut off all the terminals (male and female) and crimped on new ones.

I then recorded another log (this time, idling from a cold start).  It was clear that the corrosion wasn't the cause of the problem, as lambda activity should register once the coolant reaches 60C:

Purple: coolant temp
Blue: lambda voltage
Brown: engine speed

This morning, I replaced the sensor and recorded another warm-up:

Lots of activity at 60C this time!

A 20-mile road test confirmed that everything was back to normal.

But I'm still puzzled that a failing (or failed) O2 sensor could cut ignition 100% at times, rather than simply cause a lot of rough running and misfiring.  Can anyone shed light on that?

JV

 

Jonathan Kay
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Thanks for adding the answer. 

Jonathan

aerobod
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Hi John,

I think the voltage of the duff sensor dropping to a low value (that it seems to do when you have the "cuts") could cause a significant increase in the amount of fuel due to the ECU detecting a lean mixture due to the low Lambda voltage, the excess of fuel in that case would cause the plugs to foul temporarily. Using full throttle would overide closed loop control and default back to the open loop fuel value.

Your final injection time plotted on top of the Lambda voltage and engine speed  together with Lambda control state would show if that was the problem.

James

John Vine
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Thanks for that, James.  So, during the cuts, more a question of too much fuel rather than too little!

Are "final injection time" and "Lambda control state" specific Easimap panels for a 992?  I can't see them on my recording.

JV

aerobod
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Looking back at my old 992 traces John, I have Short Term Lambda Control Status and Final Injection Time, but Adapted Fuel 1, Adaptive Map Output or TPS Fuel + Trim would probably show a change in fueling, too.

James