B1210 What is this injector correction?

[towbar]

Hi
I am trying to determine injector latency ( dead time) for factory LS3 injectors. B1210 shows correction for different voltages and pressure differentials (delta) across the injectors. This looks like the dead time correction (in mS). Can someone confirm this?

Jeremy

[5.7ute]

Not exactly. The offset in these tables denotes where the Injector flow (hi slope) would intersect the zero flow line if it was a constant value.(which it isn't) The injector dynamics website has some good articles on this.

[joecar]

+1 what 5.7ute said.

Injector ramp up flow (i.e. as the pintle is opening) varies with voltage and pressure delta... B1210 provides the time correction for this flow variation (it is not dead time), and can be derived from the high slope mentioned by 5.7ute.

[towbar]

Thanks for your answers.

That does verify what I was thinking. So the B1210 then is actually a more useful representation than dead time. Although the injectors actually go through a period of partial opening, the B1210 value represents a time equating to the overall loss of fuel due to that opening. As long as pulse widths are greater than the time it takes for the injector to fully open, then the correction holds true. Obviously the value changes for voltage and pressure differential across the injector. Hence the table.

For those that are running an old school return type fuel regulator with vacuum connection (the best way?), pressure differential is not a variable.

Cheers

[swingtan]

Depends on your final goal.....

B1210 is a correction table for how much fuel will flow under the given conditions (Vacuum vs. Voltage). Change either of these conditions, and the injector will flow a different amount of fuel for a static fuel pressure. It has little to do with "dead time" in a classical sense.

Dead time is the portion of time that power is applied to the injector, but NO fuel is flowing. It's the time taken for the pintle to move enough to let fuel in and while this time is effected by Vacuum and Voltage, B1210 is not the corrector for this event.

To correct for "dead time" AND the non linear fuel delivery of very short pulses, you want to look at B1204. This table adds time to a commanded pulse to correct for the non linear fuel delivery of very short pluses. Combined with this is B1203, which is the shortest pulse the ECM can command and could be considered the "real dead time" of the injector.

All this being said though, if you are using stock injectors with a stock ECM, there should be no need to change any of these settings.

Simon.

[towbar]

Thanks for the lesson. I am sure others will also benefit from this info.

To be perfectly honest I will be running a 'Link' ECU on my engine. It is a little simpler in its operation than a GM one, but tuning involves less guesswork than an E38. I am finding a lot of useful info in the GM tunes for translating fuelling and ignition

Since the injector pulse width in my application is never below the value in B1210 then actual "dead time" is probably irrelevant. The correction in my ECU seems to be a similar thing to B1210. Also the LS3 B1210 table I am looking at has injector 'differential' pressure on the vertical axis. Since this pressure across my injectors is always constant then only one row applies. Voltage is the only variable. So I think I may have what I need.

Regards
Jeremy

[5.7ute]

I hope the "link" computer has evolved since I last saw one. You had better fuelling control with a bucket & several different sized nails than the earlier pcm would give.
FWIW you should do a search on the ls3 to ls1 pcm thread. The values from Joecar's spreadsheet may make more sense for the link.

[towbar]

Yes the Links have indeed evolved. There are many sub 10 sec street cars and a 6 sec drag car running them here in NZ. Since this an EFIlive site I will refrain from posting a link though.

Thanks for the tip on Joecar. I'll check it out.

[joecar]

See here: Running-an-LS3-swap-in-an-LS1-vehicle-base-suggestion

[joecar]

More: LSx-to-LS1.zip