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what to log to determine injector duty cycle


3bar
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Hi, new to PCMTec and I am used to a parameter "injector duty cycle %" or similiar used in other ecus and if you go past 80% your injectors are typically open 100% of the time (deadtime included)

in PCMtec i have found inj pulsewidth and typical values are 0.44 to 0.53 under WOT so i am looking for an equivalent in PCMTec

I dont want to assume that that means 44% and 53% injector duty cycle and hence I have lots of headroom available - so please can you point me in the right direction to determine if i am good with injectors or maxxed out ?

 

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  • 3bar changed the title to what to log to determine injector duty cycle

From memory I don't think the PCM actually calculates duty cycle. Most other packages would just have a math formula to guesstimate the duty cycle.

Pulse width is the width of the injector pulse in microseconds, 0.44 microseconds doesn't sound right.

You can calculate your duty cycle from your pulse width fairly easily. Basically you work out the duration of a revolution at your given rpm, this gives you a window and you can divide it by your injector on time. There are calculators if you google it.

Personally I find pulse width more interesting as it is comparable across the rpm. Eg 100% duty cycle at 6000 rpm would be far lower at 3000 rpm. Peak torque almost always correlates with peak pulse width as well which makes for and interesting graph.

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  • 2 years later...

Hey Roland 

On pulsewidth, I am finding the logs to be displaying very large numbers.

As can be seen here.. Maybe the wrong time divisor in this parameter?

bf wagon std

Cheers Rob

Pulsewidth.PNG.74c8de4e26109dcfd55ca097c5dca179.PNG

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On 11/16/2019 at 1:42 PM, 3bar said:

Hi, new to PCMTec and I am used to a parameter "injector duty cycle %" or similiar used in other ecus and if you go past 80% your injectors are typically open 100% of the time (deadtime included)

in PCMtec i have found inj pulsewidth and typical values are 0.44 to 0.53 under WOT so i am looking for an equivalent in PCMTec

I dont want to assume that that means 44% and 53% injector duty cycle and hence I have lots of headroom available - so please can you point me in the right direction to determine if i am good with injectors or maxxed out ?

 

MID42591 is injector duty expressed as an absolute value (0.0>1.0) you can convert it to a percent, by disconnecting your session (press vehicle), then you can change the units from absolute to %, then reconnect to the car (press vehicle button again).  Also have a look at MID42654, this will tell you if the PCM is commanding the injectors above 100% and you are clipping.

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4 hours ago, rfh said:

Hey Roland 

On pulsewidth, I am finding the logs to be displaying very large numbers.

As can be seen here.. Maybe the wrong time divisor in this parameter?

bf wagon std

Cheers Rob

 

 

That is interesting. From memory MID36175 is in us not ms, so I think the value you are seeing there *might* be out by a factor of x1000.

Could be an equation issue....

can you please go  Help > Upload files to support > Upload editor log files to support from a logging session that is looking at this channel.

 

Can you compare this value to MID36178 (Bank1 Injector Pulse width) and send me another screenshot to support@pcmtec.com?

 

 

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