Injector Latency

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UNISA JECS
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Injector Latency

Post by UNISA JECS » Sat Jul 26, 2008 1:16 pm

Hi Matt,

Got a question, in this screen shot is "1440" in "µS" aka MicroSecond?

or

Is 0x48 Hex translated to 72 Dec in "µS" aka MicroSecond?

Image

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Post by Matt » Sat Jul 26, 2008 9:29 pm

the 72 dec is raw and translated to 1440uS

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Post by UNISA JECS » Sun Jul 27, 2008 3:44 am

Matt wrote:the 72 dec is raw and translated to 1440uS
Ref: S13 KA24DE.bin

Ok so 1440uS = 1.44ms (which is a pretty big lag time), so my next question is, is this derived from the factory ECU or is this something that is set by you to be "safe" or a starting point of such?

Im just wondering because its funny if you were to open TunerPro it would actually display 72 dec/1440uS that you get in Nistune as 72ms in TunerPro.

Lastly what brought this up for me is I am using 370cc injectors and it seems that the best latency has been around mid-600uS to high-700uS which is cutting the satndard latency in half just about and this helps to get the engine idling around Stoich with o2 flags disabled and zero'd.

P.S. So might TunerPro have it wrong or atleast the translation from a Nistune bin used on TunerPro?

Example:

In Nistune the stock value is:
1440uS = Microsecond
1.44ms = Millisecond
Hex = 48
Dec = 72 (Raw)

In TunerPro the stock value is:
0.72ms = 720uS

I dunno if it a difference in the way TunerPro interputs the Nistune bin or ot appears TunerPro uses the Dec(Raw) value as its latency?

*Is there a way to monitor Long Term Fuel Trim and Short Term Fuel Trim on a OBDI ECU?
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modulation
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Post by modulation » Sun Jul 27, 2008 11:33 am

UNISA JECS wrote: *Is there a way to monitor Long Term Fuel Trim and Short Term Fuel Trim on a OBDI ECU?
I don't think fuel trim or something similar exist on OBDI Nissan ECUs.

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Post by Matt » Sun Jul 27, 2008 5:08 pm

There is a fuel trim 'alpha' but not a map as such which is reported by consult

I'll have to check again into the latency calcs inside Nistune.

We found compared to the factory latency values for injectors the nissans ecus were reporting half. So the tunerpro interpretation may be correct

I came up with the calculation from japanese ROM editing documentation and observing changes on the scope in regards to latency output on the injectors. It might be best to get this matching the manufaturing latency values

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Post by GZ@hybridka » Mon Jul 28, 2008 12:12 pm

I would suspect there may be a different translation required for different ecus, ill look into this next time I get a chance (KA/SR ecu).

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Post by Matt » Mon Jul 28, 2008 2:10 pm

I should have checked this last night, since I had a few ECUs running on the bench. I'll check it out later tonight and see what the actual scope reported differences are between RB20/SR20/KA24 ECUs

The advertised value was about half from memory

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Post by Matt » Wed Aug 06, 2008 2:33 pm

I checked this out finally this morning with the scope on the injector wires.

The tunerpro definition is correct. Its a range of 0 - 3000uS rather than 0-6000uS so I've updated the range inside Nistune. This change will be available in the next version

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Post by UNISA JECS » Mon Aug 25, 2008 4:06 am

Hi Matt,

Just wondering when you test the injector latency with the scope, are you doing this with the injectors under pressure i.e. (43.5psi) or no pressure at all.

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