Stock 440cc injector dead time info wanted

andrew_mx83

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#1
Hi all

Looking to improve the idle quality on my Megaquirt setup has me looking at injector dead times.

Does anybody have any hard numbers for the stock 440cc injectors? The MS is looking for:
Deadtime in ms at 13.2v
Battery correction in ms/V

I am running the stock 7mgte low impedance 440cc injectors through a stock resistor pack.

Thanks in advance!
 

3p141592654

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#2
From the ECU they used the following.

Image1.jpg

These are amazingly good numbers. I have always been surprised when I compare to other injectors of that era.
 

andrew_mx83

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#3
Thanks Pi, that's exactly what I was looking for. Much appreciated.

Although, I am a little confused you managed to pull these numbers from the stock ecu. Doesn't it fire the injectors with peak and hold?
I thought latency only applied if using saturation mode? Or can the peak current time be used to approximate latency?
 

plaaya69

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#5
I do not know if it will help but maybe download the ECU Masters standalone tuning software and a 7mgte base map and under the fueling tab you can see what it is set to?
 

3p141592654

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#7
Yeah, makes you wonder why they went to the trouble of the external resistors. All I can think is that they wanted to reduce the injector inductance to make them switch faster. They do have very nice performance.
 

andrew_mx83

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#8
I have no idea about injector performance unfortunately but the change in latency with voltage was about half of the default value in the ecu so I guess that's a good sign.

Any comments on the non linear flow region of these bad boys? I have fairly low idle PW (1.3ms) and not the most stable of idle AFRs even with the dead time correct and I'm wondering if they are still in the non linear region.

For any future MS users the closest numbers I could come up with for that curve are:
Dead time @ 13.2v = 0.68ms
Compensation = 0.1 ms/v
 

Drillsdeep

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#9
Looking at ecu master base map for 7mgte and the numbers are double 1.25 at 14 volts. Having similar problem afr's at idle are in the 9's. Have tried changing ve table to 50 and lambda target to 175.