Injector Dead Time Values

[Alf]

Does anyone know the dead time values for the std RB25DET 370cc purple injectors?

Pic is the RB Link G4 base map values that use an RB20 with GTR 440cc injectors.

Edited February 15, 2016 by Alf

[KiwiRS4T]

From Google:

stocker injectors are 370cc and .63ms latency

[Alf]

I'm assuming that's at 14V?

What about other voltages?

Edited February 15, 2016 by Alf

[Alf]

Only info I can find is here. http://injector-rehab.com/shop/lag.html

This will have to do.

[Ben C34]

You could try and get the info out of a stock nistune map

[jiffo]

From Datalogit, R33 Rb25det, Inj Lead times:

16V 0.320

14V 0.528

12V 0.700

10V 0.880

8V 1.060

6V 1.188

[Dose Pipe Sutututu]

another workaround (if you don't know what the deadtimes are), set roughly what you think the dead times are..

set your VE on your fuel map to 80 or so then adjust the deadtimes till your AFRs are stoich.

[Ben C34]

Actually, better yet, get bigger injectors!

[Alf]

Actually, better yet, get bigger injectors!

This is just to get motor run in and sorted.

another workaround (if you don't know what the deadtimes are), set roughly what you think the dead times are..

set your VE on your fuel map to 80 or so then adjust the deadtimes till your AFRs are stoich.

That sounds like a good idea.

So increase the fuel map % so the highest is around 80% giving it better resolution?

[Dose Pipe Sutututu]

^ no no no.. only the idle cells, it's just a way to determine the dead time at x voltage.

So what you do, set the VE to 80 for cells around idle 0 to 50kPA and 0 to 900 rpm. Start car, monitor the voltage then adjust the dead time till you hit stoich.

Of course all other VE cells will need to be adjusted to suit as the base map isn't really ideal.

[Scott Black]

alternativly if the ecu supports changing from sequential to batch fire have it running at a stable afr using batch fire, then swap to sequential if its leaner when sequential then increase dead times, if its richer decrease, and change back and forth like that until there is no change in afr

[mr skidz]

^ no no no.. only the idle cells, it's just a way to determine the dead time at x voltage.

So what you do, set the VE to 80 for cells around idle 0 to 50kPA and 0 to 900 rpm. Start car, monitor the voltage then adjust the dead time till you hit stoich.

Of course all other VE cells will need to be adjusted to suit as the base map isn't really ideal.

Setting idle fuel load cells with a VE of 80 on most engines would be throwing mixtures in the mid to high 11's and possibly even deeper into the 10's or more as VE is dependent on the VE of an engine, all are different.

if the engine has cams and some brappy overlap good chance you'll be adding way too much fuel in those load sites causing the car to stall at an instant. Instant plug foul.

I'm not sure how your example can give you a accurate dead time as dead Times need to be measured over voltage and fuel rail pressure.

that data cannot be obtained while it's running in a car unless you're adjusting your voltage in your car somehow and see no erratic change in your Afr.

Even then you'd still be guessing

Edited March 4, 2016 by mr skidz

[Dose Pipe Sutututu]

It's more of a guestimate way of setting it up rather than getting it precisely correct, many tuners have done that in the past namely PowerFC days.

Of course getting trade right data across voltage vs. lag time is ideal however it may be difficult to obtain data for stock side feeds hence the recommendation.

[mr skidz]

Many tuners do all sorts of things to get that I agree but it's called close enough.

80% VE at idle is not a good idea and you'll quickly be pulling plugs out from fouling.

The correct data would be voltage vs fuel pressure = lag time

[Dose Pipe Sutututu]

I'm guilty of doing this, but if you drop the dead time enough you'll hit stoich on idle.

[mr skidz]

I'm guilty of doing this, but if you drop the dead time enough you'll hit stoich on idle.

Yes you will hit stoich but choking you're dead times to decrease fuel supply to your fuel map is bodgie hard that's not the way to get your afr's correct and all your numbers will be ass about in your base map which is your foundation so it needs to be perfect before any subfolders are corrected otherwise you will chase your tail forever and never have anything working correctly.

so all your correction maps will never be correct.

Even cold start percentages like intake temperature corr and so forth.

If you put your high beams on I bet you your air fuel ratio changes?

this is what dead time is all about.

Edited March 5, 2016 by mr skidz

[Dose Pipe Sutututu]

Yes I am 100% of all this, but if you have no data how else you going to set it?

With the high beam thing, easy go monitor your voltage and tweak the voltage vs dead time table when your head lights are on.

I've see a handful of tunes from reputable workshops that have a linear straight line as their dead times.

[mr skidz]

If your happy with close enough than that'll work. I wouldn't settle for that myself.

changing VE on base map to 80% at idle is not correct approach your best to Change the Dead times which is clearly the issue everything else is a band-aid approach that's all I'm saying.

Workshops do all sorts of weird and wonderful things unfortunately.

For every awesome successful build that happens I'm sure there's 10 that we don't hear of that are horror stories just saying.

Edited March 5, 2016 by mr skidz

[Dose Pipe Sutututu]

Yes I am happy with that if I cannot find any data for an injector however these days everyone runs modern top feeds so the data is avaliable to just copy paste into a table.

If someone brings a car for me to tune with high flows I never use the data given, especially off Five O's site. Those numbers don't work at all.