SHORT PW OFFSETS HOLLEY SAYS NO!

Basically says it all.


GM computers have this table in the settings.. 2 tables. 1. Voltage vs PW offsets... and 2. Short Pw table...


I sent a email requesting the specs for the Accel 30lb i run, as well any other they have so we could build a database for everyone.

I get a email back saying injectors don't work like that, or Holley made ones don't.. (SEE EMAIL RESPONSE)..

I replied and told him that couldn't be right as it is a real setting dating back to even TBI/TPI and 1st gen EFI computer settings made by GM.. I am sure if it wasn't a "REAL THING" then GM wouldn't have a table for it let alone specific values in said tables.


I mean.. How or what is he saying when he says "INJECTORS DON'T WORK LIKE THAT"?!? Or theirs don't?!? Minitimer injectors are minitimer injectors.. Plenty people run Accels.. Closest to factory TPI injectors running wise i have seen thus far. Better than even the Ford Racing 30lb SVO's to me....


I currently have a EBL P4 and want it as close to perfect as i can get the tune, it as well as the original SD 7730 (BOTH) have these tables and why this tech thinks it's wrong or non existent is beyond me..

Can someone maybe elaborate on his thinking, or explain to me what this setting is or does in more detail or why someone would say it doesn't matter or along that line of thinking? To me it's a bunch of small settings and getting them right that can make a tune perfect vs bearable.. And to me if i can't do it all the way right then why even try?!?.. Get what i mean?!?


T.I.A

Adam

I've long suspected that many aftermarket supplies cut corners, including technical support staff.

There's a slight time lag when the injector driver sends a signal to the injector to flow fuel and the injector actually opens to flow fuel from the injector.

Yeah his responce blew me away especially considering how many Holley brand injectors from all their different brands there is being used today!!

I guess the stock AUJP values will get copied as it ran top notch with it.. Just have to see and pay attention to tip in etc and idle.

Sad when they don't even have the specs for their own products.

Quote:

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Originally Posted by dave w

I've long suspected that many aftermarket supplies cut corners, including technical support staff.

There's a slight time lag when the injector driver sends a signal to the injector to flow fuel and the injector actually opens to flow fuel from the injector.

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That is only part of it. The injector will also not have linear flow at low pulsewidths. There is a delay until the coil unseats the pintle and non linear flow until the injector is wide open and spraying fuel at the specified flow rate.

So what is it that you recommend?

From what i can tell the Accels are the closest performance wise to the factory Rochester/Multecs types in how they preform and act.

They are quiet and do really well, i am just curious to see what can be done or what we should use because at this point (ANY) "FUEL INJECTOR' purchased from Holley isn't gonna be close or pas perfect as it should be due to their own missing knowledge/nomenclature of their products....

https://documents.holley.com/accel_i...ons_150130.pdf

Found at: https://www.holley.com/products/fuel...uel_injection/ --> Injectors -- > ACCEL - FUEL INJECTORS - 30 LB/HR --> Injector Specifications Part# 150830

Hopefully this helps.

Quote:

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Originally Posted by dave w

I've long suspected that many aftermarket supplies cut corners, including technical support staff.

There's a slight time lag when the injector driver sends a signal to the injector to flow fuel and the injector actually opens to flow fuel from the injector.

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I write OEM software, that's why I don't post on here very much. But we compensate for a lot of things - current buildup time (vs battery voltage), fuel pressure (we have a fuel rail pressure transducer so we just measure it) - and this is a signed offset because it depends on both closing and opening delay times and they are affected differently at varying pressures, and low pulse width nonlinearity although this can sometimes be a bit of a spotty calibration depending on the injector. We also have calibrations for fuel pressure pulsations (vs engine speed and fuel flow rate), and for MPFI/GDI engines we'll have both static (calibrated) and adaptive cylinder-specific fuel trims. I am surprised that Holley just said that injectors don't work like that because clearly they do, although you have to approach that bottom end of the curve with some degree of trepidation and a lot of testing. We found that you could calibrate for one engine down there, and depending on the injector calibration and tolerance, you could end up with an application where 30% of the vehicles idle terribly and fail emissions. But some injector models are really good down there.

Hiya,
Agreed. There are many things happening in that fuel rail, transient fuel temperature and pressure for example.
In the early 2000's, when the bean counters decided to get rid of the dampeners in the fuel rail, my bud at GM fought hard to keep them. It was decided to get rid of them and the calibration engineers would have to "step up" :innocent2:
He quit that division and moved to stabilitrack, taught some of the Bosch boys some stuff. Cop cars would crash themselves trying to pit his tahoe :laugh:

Another note, in 2010 we took off the showroom Camaro's to CARB to get bag tested, 4 failed before we got one to pass before we made our mods. It's a friggin joke.

If you have room in the packaging, larger rails win, -12 or larger :)