[Frit]

1. Could the SAMRAT scaler described as Air - MAF Filter Sample Rate limit the EEC on how much air flow it can handle?

Looking at the A9L bin, its set to 2 clock cycles, but if I have found the right setting in the A9U2, its set to 4 clock cycles. Would this create the 1400kg/h limit?

2. I noticed the A9U2 has PRLDSW - Air - Load Scaling Switch (Percent Load) set to 1, which essentially states that LOAD & LOADX equals. Now I've noticed that when I datalogged the car LOADX never went above 133%, which is what the function FN035 - Air - Load Scaling Seallevel vs RPM is set to from 0 RPM's to 16384 RPM's.

Despite the description stating that FN035 is not used if PRLDSW = 1, it does look like it sets the limit that LOADX can reach.

Obviously my car is going above 133% load, and I have seen LOAD creap over 200%. Can I increase FN035 to 200% and what ramications will it have other than limiting LOADX?

[sailorbob]

'FAM Filter Sample Rate' (aka SAMRAT) is used to pace the filter rate for the filtered airmass in terms of program background loop counts. It is an idle related parameter.

[EFIpunk]

1. No, as bob said...there is a hard limit of 64#/min. in the PCM.

2. You need to set the sealevel to the max load you see at that rpm or set the switch to 1.

[Frit]

The switch is set to 1 by default because its a supercharged application.

I feel like I'm caught between a rock and a hard place here. I get told by some I need to scale my CID down etc so the EEC can handle the bigger MAF and injectors because it can only handle 1400kg/h (51#/min). In this case LOADX and LOAD do not match and its actually screwing up my spark.

I then get told by others there is no need to scale everything down because there is no limit meanwhile I see my load values peak to 133% and lock there meanwhile my car is taking in more and more air and giving more and more fuel. LOADX and LOAD are equal in this case but I have already seen LOAD values over 200% .

Ggggrrrrrrr I'm getting more and more confused by the minute

Anyway, now I need to figure out how to get LOAD to come down to being in line with LOADX.

[EFIpunk]

If the switch is set at 1 then don't even look at loadx. There is a hard limit, if you have reached this there is only one way to fix it. A: get a MAFia(what I would do) or B: get a SCT BA MAF.

[86GT]

1. No, as bob said...there is a hard limit of 64#/min. in the PCM.

Not to sure this is correct.

64 lb/min = (64/2.2*60 = 1745) kg/hr.

I have a C&L 85 with a 2800 max and I have no issues entering that.

[EFIpunk]

Actually it is at 63.9#/min. I have seen alot of parameters in caledit that exceed there max.

[86GT]

If it exceeds the max then how am I able to read the value back as a raw bin and the numbers are correct and those numbers exceed 63.9?

[EFIpunk]

I didn't say you couldn't enter a value larger than the limit. In the PCM there is a hard limit in the code, however I'm not a programmer. I have talked to many SCT tuners along with Jerry W. and Diablo CMR tuners. This is the entire reason behind the BA2400 & BA2800 MAF's

[Frit]

The max limit is not the value that can be entered into a location in the EEC. Its the max the EEC can process while its running. With the A9U2 12mhz processor the max it can run is 1400kg/h. My 76mm C&L is capable of flowing up to 2000kg/h and I can put those values into the maf transfer.

My car has so far hit a peak of 1150kg/hr now at 5000rpm's, and I have no idea what will happen if I hit that supposed wall.

I've scaled everything down by the difference of the injector size I changed to, but now I'm seeing different LOADX and LOAD values instead of the them being equal, which is throwing off my SPARK while in CL. OL spark is just a function based on RPM and it works fine.

[cgrey8]

...I feel like I'm caught between a rock and a hard place here. I get told by some I need to scale my CID down etc so the EEC can handle the bigger MAF and injectors because it can only handle 1400kg/h (51#/min). In this case LOADX and LOAD do not match and its actually screwing up my spark...

I wonder if the problem is that the scalar does set Load=LoadX, but then after that is done, LoadX hits some other value-limiting control that does not affect Load? That's just a guess...

...Ggggrrrrrrr I'm getting more and more confused by the minute...

I'm sure a lot of the confusion comes from the fact that "we" know how to do things in GUFx strategies, which may not directly apply to your strat for yet unknown reasons. So unfortunately, the people (myself included) giving the advice aren't wrong, they just aren't right for the EEC you are using.

As for your max MAF and max Load, there's a similar wall in the GUFx defs defined by FN037 - Airflow MAX vs RPM where the airflow is in units of lbs/intake. By default, this limits the GUFx defs but I can't remember the exact details. It seems it limits Load to something ~150%. Increasing the values in FN037 is supposed to allow for higher load values...or at least that's what I remember. I can't even remember where that was discussed now. Anyway my point is perhaps your EEC's strategy has a similar function that's limiting your MAF and/or load?

[sailorbob]

As cgrey8 said there is a 'Air Charge Maximum' (aka FN037) parameter in GUF* strategies and GURE has this too. This determines the maximum instantaneous air charge value the engine can hold for a given rpm; i.e. the calculated instantaneous air charge value is clipped to this.

It is this value that becomes the limiting factor in what the airmass the eec can handle and it is unrelated to processor speed. The binary point scaling of this parameter is the problem and you will not get around this without re-writing sections of the code. If you are hitting this limit then you will need to resort to fooling the eec by doing things like halving the MAF flow and injector flow etc. The limit in GUF* and GURE is approximately 0.0039 lb/intake.

BTW, this function deals with airmass not air flow, i.e. it is not time related.

If you have the 'Percent Load Switch' (aka PRLDSW) set to '1' but are seeing different values for LOAD and LOAD% then I think that the address for this parameter is wrong or you are not datalogging LOAD or LOAD% correctly.

EDIT: Confirmed GURE does have FN037 and it's maximum value.

[stanger007]

With the latest additions to my combo, the 63.9lb/min limit is going to be an issue on my CBAZA car.

SCT recommends multiplying the CID, Injector High/Low and MAF Transfer by the same value - a number less than 1.

Why doesn't this come up more in discussion? Do people rarely hit the limit and start going lean or is what my wife says about me not listening really true and I have just missed all the discussion on this limit? :)

Wes

[cgrey8]

I think it doesn't come up that often since there are very few people here that "need" injectors that large on a V8.

What are you installing that you will be needing over 60lb injectors for?

[stanger007]

I think it doesn't come up that often since there are very few people here that "need" injectors that large on a V8.

What are you installing that you will be needing over 60lb injectors for?

Were you directing this to me? I am talking about the limit on the MAF's air measurement, not on injectors.

Wes

[Frit]

Ok, thanks to Bob I managed to sort some things out. What I thought I had as FN035 was actually FN037, and that led me to find FN035.... which after doing some calculations I confirmed FN037 and it looks like the GURE has PRLDSW = 0... which means I need to go find that setting

Anyways, here's FN035
16384 1.20
5000 1.20
4000 1.28
3000 1.25
0 1.07
0 1.07
0 1.07

and here's FN037
16384 2.60001
0 2.60001
0 2.60001
0 2.60001
0 2.60001
0 2.60001
0 2.60001
0 2.60001
0 2.60001
0 2.60001

Now the interesting thing to note here, was when I had FN037 calculating as FN035 the 2.6 actually worked out to approx 1.33. Now the darnest thing is, the day I datalogged the car with everything at full scale, LOADX never went over 133% even though LOAD kept climbing.

Well this answers a few things so thanks for the nudge Bob.

[Frit]

With the latest additions to my combo, the 63.9lb/min limit is going to be an issue on my CBAZA car.

SCT recommends multiplying the CID, Injector High/Low and MAF Transfer by the same value - a number less than 1.

Why doesn't this come up more in discussion? Do people rarely hit the limit and start going lean or is what my wife says about me not listening really true and I have just missed all the discussion on this limit? :)

Wes

50# and 60# injectors are pretty much common these days for the TBird SC's to prevent leaning out. Heck we've got a couple of guys now leaning out with the 60's and are now looking at a getting a conversion kit to run low impedence and going to 80# injectors .

I'm already seeing about 87% Inj Duty at 5000 now with my little setup with 42's.

[sailorbob]

Frit, your output conversion for FN037 looks wrong, I'd expect to see values around 0.0026000 lb/intake.

[cgrey8]

Frit, your output conversion for FN037 looks wrong, I'd expect to see values around 0.0026000 lb/intake.

In BE, it's 2.6000 for GUFx but in the units, it's indicated that the value is x1000.

And yes Frit, for a V6, I would expect the injector needs to go much higher since you have less cylinders making the same output.

[sailorbob]

it looks like the GURE has PRLDSW = 0... which means I need to go find that setting

Try address 0x98B0.

EDIT: amended 0x98B1 to 0x98B0

[EFIpunk]

This is for all year, just scale what you have. Load thr correct transfer....scale slopes, breakpoint, cid and manifold volume.

[Frit]

it looks like the GURE has PRLDSW = 0... which means I need to go find that setting

Try address 0x98B1.

It has a 0xFF there, and I was originally looking at 0x98b0 which contains a 0x01. The A9L at 0x9A80 has a 0x00 then a 0xFF in the next address.

[sailorbob]

I have corrected my post above, I realised my typo almost immediately but kept getting the 'table sessions is full' error and couldn't log on to correct it soon enough

[Frit]

I have corrected my post above, I realised my typo almost immediately but kept getting the 'table sessions is full' error and couldn't log on to correct it soon enough

No problem :)... I get that error message alot to.

[sailorbob]

Would this create the 1400kg/h limit?

Where does this oft quoted figure come from? I see it also gets referred to when the eec is a 12Mhz processor speed. I'm curious because I've had a very brief look at the A9U2 code and see that it uses the same value for it's 'seconds to clock ticks' conversion factor which makes me think it's the same speed as the GUF* ecu's.

[stanger007]

Mike Glover told me this:

The limit (63.9lb/min 1740Kg/hr) begins in (IIRC) 2001 or 2002, when ford went to lbs/min instead of lbs/tic.

I've got a buddy flowing well into 2,000Kg/Hr on a CBAZA and he is doing good w/ no leanouts.

Wes

[patrickmx2]

Wow technology sure has gone wild. A 3.8 needing 60# injectors? I'm trying to wrap my mind around that when a supercharged 5.4 (331 CID) does good with 42's. What is the boost on these things? I know some of the injectors sizing has to do with overcoming a pressurized intake.

Loosing boost to better heads and intake once we noticed a reduction in inj duty cycle also. Having the supercharger upgraded regained the boost and put the dutycycle in the red zone.

I'm guessing the reason 60lbs isn't discussed much on here is because by then a 5.0 or larger project has moved on to F.A.S.T or some other stand alone EFI system and this crowd (to date) has been mostly street car oriented.

[Frit]

These are street driven cars and fully emissions compliant and still using the good ole EECIV.

Most guys using those are pushing low to mid 20's psi of boost, with some of them going over 30. Alot of them are still running on the original stock bottom end so it looks like ford built the SC version of the 3.8 a little too well ;).

These guys are up around 450hp at the wheels with about 550 to 600 ft lbs of torque at the wheels.

I'm not there yet, but the looks on peoples faces when they see they got spanked at the track by a little V6 in a car over 4000lbs is priceless :D

[patrickmx2]

Thats pretty much what I thought. 20psi of boost requires more fuel pressure and larger injectors to arrive at what a smaller injector and lower fuel pressure could do in less atmosphere. A 5.0 making 450hp at the wheels can do so with less boost and is why the discussion for 60# injectors would be rare indeed at those power levels. So I'm guessing the intakes / heads must be pretty restrictive on those Birds to generate that much boost (resistance to air flow) thus requiring more behind the injector.

It was hard for me to figure that out a few years ago until someone described it to me like this. Try blowing a tire up with your mouth. You need more pressure in your lungs than the tire has trying to get out. So before the fuel can leave the injector tip it has to overcome the 20psi of boost inside the intake plenum and at the correct volume in time for the desired PW.

I've seen a lot of 5.0 guys debate a car with less boost being able to outrun one with 8lbs more. The car with less boost naturally had to be moving and processing more air with better flowing heads, etc... and requiring more fuel but did so with a smaller injector.

So the HP/injector size formula is a good rule of thumb until you get to crazy boost levels.

[cgrey8]

Patrick, I think you are sort of right. But with a few snags in your logic.

First off, the V6 will always need larger injectors than a V8 to produce the same amount of hp since there MUST be more air going into the V6 cylinders as compared to the V8. Likewise, an L4 will need larger injectors than a V6 to produce the same output. 42lb injectors on 2.3L turbos is pretty common place and is probably on the weaker side of what those motors will do. That's about the equivalent of someone putting 21lb injectors in a 302 V8 (42 x 4 cyl = 21 x 8 cyl). This also assumes the same fuel pressure for all 3 engine types...usually 39PSI when using a stock FPR which brings me to the next topic.

Fuel Pressure Regulators (FPRs). Before we get started, let me state the obvious. The injector has 2 ports, the inlet that connects to the fuel rail, and the outlet into the intake manifold. It's the FPRs job to maintain the same differential pressure across the injector ports regardless of the vacuum or boost condition in the intake. As long as the differential pressure between the intake and fuel rails is the same, the injector should behave exactly the same regardless of whether the intake is under vacuum or heavy boost. Thus, you were right that with a boosted application, that 20psi has to be overcome somehow in order to get the fuel out of the injector. But it's not the injector itself that has to overcome this. As long as the injector is sized to the size of the motor, all is good. That being said, it's actually the fuel pump that takes the brunt of heavy boost. Thus with an FPR setup for 39 PSI with the vacuum line removed, at 20PSI, the actual line pressure will be closer to 59PSI. A car pushing 30PSI boost down the throat of the motor, is putting 69PSI to the rails. This is why it's so crucial that boosted applications have a much stronger fuel lines AND a high pressure/high volume fuel pump(s) as compared to non-boosted applications. But ultimately, whether the intake is at vacuum or boost, the injector is still only experiencing 39PSI of differential pressure. Make sense?

So why is maintaining the differential pressure so important? It's important because the EEC is expecting/assuming that the injector will always deliver the same amount of fuel for any given pulse-width regardless of engine condition. In Closed Loop, this isn't as big of a deal, since the EEC will respond to HEGO feedback. But in Open Loop conditions like WOT, there is no feedback so the EEC's assumptions about fuel delivery are important so that it reliably delivers a close accompaniment of fuel for the measured RPM/Load.

You are very right that a less-restrictive head and intake will result in lower boost since it moves more air easier...thus why a lower boosted motor can produce more power than a higher boost motor with the same CID. Also when there is lower boost, there's lower parasitic load on the motor to produce the boost. So more of the motor's energy production is going out the back of the crank where the transmission is as opposed to the front where the supercharger is. Higher PSI doesn't always mean higher HP to the wheels.

But this doesn't explain how that can happen with a motor with smaller injectors. There are two possibilities here

1. The lower powered motor with larger injectors simply was undersized for the injectors that were installed in it. That one's easy to see.
2. The motor with smaller injectors had an Fuel Monitoring Unit (FMU) instead of an FPR.

FMUs do something a little different than FPRs. FMUs are designed to increase the differential pressure across the injectors, not keep it the same. They are used on boosted applications where the injectors are UNDERSIZED for the application they are in. Where an FPR will maintain say that constant 39PSI differential pressure, the FMU will gradually increase the differential up to 45-50PSI. What this does is force more fuel through the injectors making the undersized injectors act larger than they really are. FMUs should only be used on lightly boosted applications up to say 6PSI. My personal opinion of FMUs is that they are a hack...nothing more than a poor man's crude way of getting HP from undersized parts. From what I understand about them, the AFRs produced on FMU motors isn't very stable or reliable. AFRs can range from 10:1 to 13:1 depending on the conditions. To do the job right, you should use a normal FPR, back it up with injectors large enough to handle the job, and tune the EEC to deliver the correct/desired amount of fuel regardless of the engine condition. This increases performance and lowers the brunt on the fuel system by keeping the pressures from being excessive.

Now my disclaimer...I can't claim to be an expert in this arena since I don't have any experience with boosted applications. So take this info with a grain of salt. But this is how I understand things to work. So take that and decide for yourself what's right and wrong.