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Coding of injectors - Not necessarily LR related


Peaklander
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My old day job was developing the Delphi diesel injectors for trucks.  This included specifying and writing the coding requirements for them.  Known as trimming the injectors.  Also included teaching the trimming process within Delphi.  Bosch and Delphi run similar systems for trimming.  I've also done work for Denso and theirs are done a different way, no where near as good!

 

You can run the injectors without inputting the codes without worrying about damage to the engine.  The injectors are tested on an end of line test rig.  The test plan runs the injector at set logics.  Logics are just how long the signal going to the injector is - example: 500us, 750us, 1000us etc....  Record the fuel at each point and then compare to a master injector, or ideal fuel performance.  The performance has to be within a certain range before any trimming is done.  You can't use the trimming process to correct a 'bad' injector.  So uncoded they can't be that far out - but far enough to affect emissions and fuel economy.

Then you use the deviations from the ideal fuelling performance to creating the coding.  That's the simple explanation, the detail is very complicated and very few people in either Delphi or Bosch understand the detail well enough to create new trimming set ups.

 

Hopefully that makes sense.  If anyone want's more detail or has got questions I'll have a go at answering them.

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2 hours ago, Raumer said:

My old day job was developing the Delphi diesel injectors for trucks.  This included specifying and writing the coding requirements for them.  Known as trimming the injectors.  Also included teaching the trimming process within Delphi.  Bosch and Delphi run similar systems for trimming.  I've also done work for Denso and theirs are done a different way, no where near as good!

 

You can run the injectors without inputting the codes without worrying about damage to the engine.  The injectors are tested on an end of line test rig.  The test plan runs the injector at set logics.  Logics are just how long the signal going to the injector is - example: 500us, 750us, 1000us etc....  Record the fuel at each point and then compare to a master injector, or ideal fuel performance.  The performance has to be within a certain range before any trimming is done.  You can't use the trimming process to correct a 'bad' injector.  So uncoded they can't be that far out - but far enough to affect emissions and fuel economy.

Then you use the deviations from the ideal fuelling performance to creating the coding.  That's the simple explanation, the detail is very complicated and very few people in either Delphi or Bosch understand the detail well enough to create new trimming set ups.

 

Hopefully that makes sense.  If anyone want's more detail or has got questions I'll have a go at answering them.

I'm sure I'm not alone in wanting to read more details :) 

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The Bosch injectors I have look like they are alphanumeric codes with possibly the whole range of letters and numbers in use. Also they are repeated, such as BTBB8N so that would possibly be a maximum (26+10)combinations. It's probably much simpler but I wonder how many parameters are defined by those codes?

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I'll try and write the longer version.  Will take a few days as probably need to do some diagrams.  Surprisingly difficult without access to the data. :)

 

The codes are normally in pairs.  So for your example you've got BT - BB - 8N.  First is probably for how fast or slow the injector is to start injecting.  The second is probably how fast or slow for it to stop injecting.  The final one would be to correct the amount of fuel delivered.  The latest Euro 6 injectors can have up to 40 codes.

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3 hours ago, Raumer said:

I'll try and write the longer version.  Will take a few days as probably need to do some diagrams.  Surprisingly difficult without access to the data. :)

 

The codes are normally in pairs.  So for your example you've got BT - BB - 8N.  First is probably for how fast or slow the injector is to start injecting.  The second is probably how fast or slow for it to stop injecting.  The final one would be to correct the amount of fuel delivered.  The latest Euro 6 injectors can have up to 40 codes.

No worries, will be interesting to read! :D 

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