Can anyone provide the proper offsets and constant of these injectors ?

 

Where did these values come from?

 

Here's the sheet from Southbay on my 24's. Witchunter says mine are 22's and they say the number you posted is a 20. So it's probably very close to this. Perhaps Southbay has a sheet for the 710's....

Rick

 

Thanks rick, converted and plugged in

 

Let us know how this work out and what effects it has. Easier tuning, better idle, more stable BLM?

I'm curious about how these affect the operation and what I might expect to see from a troubleshooting perspective from incorrect offsets?

Rick

 

It's on a all stock engine that will not be datalogged. I will post the results after the tgo member lets me know.
I did have one recently I corrected the offsets and the blms were locked before to 120. After the change the went to 130 and I was able to tune. The odd the int always remained at 128 .

 

Recommend unplugging the ECM and resetting it after the bin change. Probably want the ECM to forget everything it "learned" with the old offsets and start anew. End user should drive around for a while to log the new BLM's.

 

I plotted this data, fit a curve to it, and interpolated and extrapolated the numbers corresponding to the TPI table for pulse width voltage offset. I plugged in the numbers and let TunerPro find the closest matches, etc. Here's what I came up with:

(Edit: added RBob's zero voltage failsafe and also changed low voltage and high voltage to reflect OEM style mapping values):




GD

 

I was about to find out how well this works but just as I was about to start logging my cooling system gave out. So I'm a few days out testing these settings. Hopefully I didn't blow the head gaskets out of her or I'll be testing this a month from now after I swap in my spare 350.

GD

 

The 0 volt entry should be the same as the 12.8 volt entry. This is in case the ADC fails or the wire to that ECM input fails.

RBob.

 

Ok noted. I'll make that change.

What effect does the minimum base pulse width and default pulse width have?

Rick

 

There was a thread about these new Bosch injectors a while back. I contacted FIC about their 22s and they told me they were the exact same as the Multecs. Id like to know if anyone has confirmed this or not because a recent trip to the dyno has resulted in my car running a bit lean on the top end

 

Well I got my cooling system sorted last night.

The offsets seem to be working well. I did have to lower the injector constant to 22 lbs (these are "24's").

I have a feeling that if you use the factory offsets the injectors run ok-to-decent with the factory offsets and only changing the injector constant to 24. If you program the actual constants correct for the injectors they act like a 22lb injector (Witchunter says they flow 22).

So yeah..... more testing needed but that's my feeling right now.

GD

 

I edited the table and the above post to include RBob's fail-safe recommendation and also the low and high voltage numbers to better represent the OEM style mapping when voltages are way outside the normal ranges.

What role does the base pulse width play?

GD

 

Base pw is used to calculate the pulse width, the Ecm first looks up the base pulse width in a lookup table. Then rpm & lv8 etc...

 

So lowering the base pulse width would probably account for having to tell the ECU the injectors are a different size..... lower the BPW, and the ECM fires the injector for a longer interval (or more pulses)? - requiring a change to the injector size constant (smaller) to bring the system back into equilibrium. Anyone have the actual formula the ECM uses? I'm guessing that the BPW factor may have a greater effect at lower pulse width (idle, etc), than it does at higher pulse width? When I dropped this table and BPW of 0.50 into my system all my BLM's shot up and I had to tell the ECM the injectors were 22's not 24's. But that does jive with at least one source (Witchunter) that claims they are in fact 22.5's or so.

GD

 

The injector offsets don't affect WOT that much. The PW is already large, so a minor difference of .3 msec won't change much on a 6 msec PW.

The offsets are important for driveability and lower speed operation. Along with being able to get a decent idle.

RBob.

 

What MaskID? What table or value? Since you state there is already an injector flow scalar, this BPW is something else.

RBob.

 

I've found it is worth the money to either buy new injectors or have your injectors tested for correct offset and small pulse width correction values. If it is a daily driver, the smooth idle and gas mileage increase, especially low speed city driving will soon pay for the cost. The numbers you get off the internet or with the "rebuilt" may or my not be close enough. It is very frustrating to try to get a good tune at small pulse widths without the correct numbers.

 

I'm running 6E

I'm referring to the scalar's "Min IBPW" and "Default IBPW"

I assumed one of these are what the sheet from Southbay referred to as:

MINPW Minimum repeatable fuel pulsewidth at 39.15 psid: 0.521

Then there is a multiplier for 44.95 psi fuel pressure.

So I set this scalar to 0.50 (it was set to 1.60 in the factory 19lb PROM).

??

Thanks!
Rick

 

In the listed mask, "Min IBPW" is the minimum PW that is allowed. Under that the "Default IBPW" is used. However, I don't see anything to prevent the Default IBPW from being smaller then the minimum PW.

RBob.

 

How do those scalars effect the fueling calculation? Does it just compare the results of the calculated pulse width and if lower than the minimum then it defaults to the minimum instead?

Or is it used in the calculation?

I'm just trying to learn how all this interacts. Do you have the fomula used in the code for calculating injector pulse width so I know what scalars and other variables are used - that I might be able to better tune for different injectors?

Where might I find a disassembled (and preferably commented!) $6E? I'm no stranger to assembly and I would love to help the community by sorting out this Bosch 3 injector situation once and for all. I'll find someone or some way to test the injector offsets myself if I have to. I have an injector flow bench and I'm not afraid of modifying it to get answers.

Thanks!

 

Link in the Tuning Guide Book sticky under the '7165 ECM:

https://www.thirdgen.org/techbb2/sho...hreadid=293764

RBob.

 

Ok so I think I understand now:

The pulse width vs battery voltage table is going to affect lower speed operation much more than higher speed so in general if my BLM's are high at low throttle/low rpm then increasing this offset will add more fuel to bring them down but will not have much effect at higher cruise.

Injector size scalars are going to affect fueling everywhere.

So what effect does the Low Pulse Width offset vs. Base Pulse Width table have? I'm not seeing much difference by changing this table. I've zeroed it out and it doesn't seem to do anything really. Is it because I'm running Bosch EV6 injectors and they don't really need much, if anything, here?

GD

 

Hey RBob, I would like to question you on this post. Are these scalars used in the "crank fuel" portion of the code? In my $6E bin, the values are both the same, about 1.59ms. In the crank fuel tables, at warmer temps, the PW is generally decreasing, and with all the multipliers, the resulting crank fuel PW could be quite small, and less than 1.59mS.
And why have 2 scalars, "min...." and "default...."? Seems like one would contradict the other, but maybe they are used differently, in the code?
Just wondering, if you dont mind.