Looking for DME BIN files

[Dave W.]

IIRC the formula for adjusting fuel injector size in the FQS table when going from 2.5 bar to 3.0 bar reg is to multiply by 1.077.

[Tom]

Awesome, thank you!! I had come up with that number using my google physics degree, which says the increase in flow is equal to the square root of the new flow rate divided by the old flow rate. So, that would mean the square root of (3/2.5), which is the same 1.095445 you list above. I just didn't know how/where to implement that reduction on the chip. Didn't think to use the FQS fuel scaling. So on a factory chip, the FQS 0 position shows a fuel scaling number of 34.6; so if I'm following along I would replace that with 31.59 (i.e., 34.6 divided by 1.095445) to account for the increased fuel pressure?

I'm curious if more pressure will actually be useful. Presumably, Bosch worked it out so the stock injectors can flow enough fuel at 2.5 bar for the entire 0-4.8 voltage range of the AFM. If so, why did some performance chips use a 3 bar FPR? My guess is that the injectors only flow 'enough' within the factory boost curve, and when you increase the boost, you get into load/rpm combinations that Bosch never had to contend with. Either that or the tuners just wanted the ability to go much richer than the factory did, in an effort not to blow up engines...

[Dave W.]

I think that's backwards. I'll edit my post above ^.

Higher number reduces injector duty cycle (IDC), lower number increase IDC. So bigger injectors or higher FP would need less IDC to flow a given amount of fuel. Bigger injectors should have a larger FQS number.
Yes you're right that the raw formula is New pressure divided by old pressure (43.5/37.5= 1.16) , take square root (=1.077)
and multiply by the current injector size. (1.077 x 34.6 = 37.26)

[Tom]

Seriously appreciate your help! Thank you.

So if I have this right, the fuel scale moves up and down with injector flow rates? If the pressure goes up, you need to increase the 'fuel scale' to let the DME know the injectors are flowing more? The factory chip does appear consistent with that, showing 34.6 at FQS 0; and 32.56 for FQS 3. If the DME thinks the injectors are flowing 32.56/34.6 or ~94% or their actual rate, it would need to increase the IDC by about 6% to get back to the same fueling level, which lines up with FQS 3 adding 6% fuel, as Porsche claims.

That said, I still get 1.095445 (rather than your 1.077), meaning I'd bump it to 37.9 (rather than your 37.26). I am using 3/2.5 bar = 1.2; but converting to psi I get 43.5/36.25 which is also 1.2. Did you use 37.5psi in your formula intentionally? Do the 2.5 bar regulators actually produce 37.5psi and just get rounded to 2.5 for marketing purposes? Or was that just a typo (math-o)? Or am I missing something altogether?

[Dave W.]

I think you're right. It's best to use 36.25 psi when converting from a 2.5 bar regulator. I was remembering another old car I owned that had a 37.5 psi fuel pressure regulator.

[walfreyydo]

Hi Tom,

I didnt read all the replies in this thread to see if these were already posted, but if you are looking for additional BIN files, Rogue Tuning still has some BIN files available for the 8vNA, 16v and Turbo here:
https://www.roguetuning.com/diy_free_944_tuning_tools

Not sure if those are stock tunes or aftermarket, but they do import into TunerPro just fine. I used them to help dial in my ignition timing for my Megasquirt tune, since I had no reference point for what was "safe" or what stock ignition timing was on an S2.

[dme]

I've got a set of APE chips I bought off eBay several years ago. Came complete with original papers, chips, and Banjo bolt.
Unfortunately, it runs very rich with my 86 951no matter which setting I select.
I don't have the ability to read them, but I can send them to you if you are interested.

[Tom]

I've got a set of APE chips I bought off eBay several years ago. Came complete with original papers, chips, and Banjo bolt.
Unfortunately, it runs very rich with my 86 951no matter which setting I select.
I don't have the ability to read them, but I can send them to you if you are interested.

That would be awesome. I'll get them back to you asap. I'd love to compare them to the later APE chips I have. Will send you a PM. Thank you!

[Tom]

My chip burning project has been on hold a bit as I clean up some other wiring/electronic adjacent to the new Kroon Harness, but I'm also a bit frustrated to report I have not received the Cobra RTP chip emulator from "Boosted NW" yet. I ordered on Nov 26, got an acknowledgement about the order, then radio silence with no reply earlier this week to my email asking about status. I guess I was lured in by their website that claims the units are 'in stock'...

https://boostednw.com/motronicrt?search ... 20motronic

Long after ordering, I discovered I'm not alone.



I'd cancel the order, but after a raft of comical excuses for delays, their website says this: ATTN: CANCELLATIONS WILL NOT BE PROCESSED DURING THIS TIME (WE ARE BUSY PROCESSING ORDERS). DO NOT ORDER IF YOU ARE IMPATIENT. ORDERS WILL BE SHIPPED REGARDLESS.

Anyone know of another emulator that works well with Tuner Pro RT?

[dme]

Thanks for the info. I was considering one myself if...I decide to keep the car.