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Is this the proper way to check dead time with injector tester?

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Just got access to an injector tester to try and diagnose and fix my idle problem mentioned here: https://www.hpacademy.com/forum/general-tuning-discussion/show/idlelow-rpm-suddenly-going-lean

While testing the stock 2ZZ injectors, I tried to confirm the injector dead time by turning the pulse width way down and crank it up slowly. Fuel only started to spray from the injector at 1.6ms and I assumed this is the injector dead time (for the specific voltage and fuel pressure I am running my test on of cause). Is this method the correct way?

I am having doubts because the dead time appears to be vastly different from what I expect and also the settings in the ECU (or maybe the deadly time in the ECU is truly wrong and it is the cause of my fuelling problem).

hello no this is not the correct way i gave you the injector dead times the other day in your other post, the correct way to measure the injector dead times

follow this link to further information https://www.hpacademy.com/forum/general-tuning-discussion/show/injector-dead-time-5

Sorry Ross, I cannot seem to find the dead times you have mentioned. Am I looking in the wrong post (https://www.hpacademy.com/forum/general-tuning-discussion/show/idlelow-rpm-suddenly-going-lean)?

Thanks for the link on how to work out injector deadtime. I just thought with an injector cleaner/tester, there would be another way to get the deadtime. Well, I guess there is no shortcut then.

Measure the injector flow rate at multiple pulse widths, I generally use 100Hz so that PW represents duty cycle - ie 8msPW = 80%DC. Do these same group of tests at all voltages you want to characterise.

Plot the results Flow Vs PW on a graph, you should get near straight lines. The average gradient or slope is your flow rate if the injector was perfectly linear, the PW axis intercept is the deadtime. I normally calculate the slope from the 2 & 7 or 2 & 8ms data points provided the plotted data fits a straight line well in this range as these generally fit the straight line well.

Example data attached.

Attached Files

Thanks Adam, that make sense to me, I'll give it a try. You attachment is missing though.

Also after reading the link Ross posted, as the injector driver on the tester and ECU will be different, once installed on the engine the deadtime might be slightly different. However, I guess it would be so small that it shouldn't matter much in most cases and can be easily dialled in.

Sorry the attachment thing is flaky on this forum, I went back to edit the post and it was already there. It seems to be showing now for me?

And yes, the injector driver circuit makes a big difference, you ideally want to use your ECU to do these tests.

I see it now, thank you Adam!

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