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Pulse Width Logging

Practical Diesel Tuning

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When logging my stock 2.8 Duramax Main Injection Pulse Width and comparing it with the stock map its way shorter right across the range by about 30%.

Am I missing something here or do you need to add pilot to it? All my other channels are on the money but not PW.

Any idea's.

Hi Graeme is the fuel pressure the same ?

Hi yes fuel pressure and desired fuel pressure are tracking good, it’s the same shorter PW on all my logging.

I think Ross was probably referring to your tuned fuel pressure vs stock (not desired vs actual).

If you've increases fuel pressure during your tuning process in order increase horsepower, this can significantly shorten injector duration for a given fuel quantity.

Edit: this brings up another question, have you been tuning on a dyno? Are you making more power or a richer air fuel ratio while the log is showing you less injector duration?

I haven’t tuned anything yet the shorter PW is stock logging and comparing with the stock PW map.

I'm not sure why it’s so far out ie. logging will say 1.3ms and stock map will say it should be 1.8ms.


Oh ok. I've tuned a few Colorado's but not in the last year or two so it's not fresh in the memory banks. It may be the way it's logging, showing effective pulsewidth (without dead time/latency being shown)

What is the actual mg of fuel in a stock tune? From memory around 90mg? And rail pressure? Does it line up with the scaling in the inj ms table? It may be interpolating between cells.

Could be just the way it’s logging, I might try increasing the logging speed for that channel and see if it makes I difference.


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