MAF Curve for Roush Sealed Airbox

[CCS86]

Hi guys,

Can somebody help me out with a MAF transfer function for the Roush Stage 1 MAF housing / airbox lid? This one attaches to a stock GT airbox.

I have one Roush calibration from the repository, but have no idea which MAF housing it is for. Roush has been annoyingly tight lipped and refused to just send over the transfer function. After a bunch of pestering to at least confirm/deny the function I have matches, they claim "no, it is not".

Much appreciated!


lid1.jpg
lid2.jpg

[veeefour]

Can't you just tune it?

[CCS86]

Can't you just tune it?

I could.

I'm in the camp of minimal-to-no adjustments to the MAF curve. Using the stock GT500 MAF curve, I have been able to get my fuel trims very good. A MAF sensor housing / filter combination should be a very well calibrated device. As long as you don't make upstream modifications, there should be no reason for it to be inaccurate. With a known good MAF curve, if your fueling is off, the issue is probably elsewhere in the tune or mechanically.

To attempt building one from scratch, when a calibrated transfer function already exists seems less than ideal.

[veeefour]

Building MAF curve form scratch takes 2 hours tops.

[CCS86]

Building MAF curve form scratch takes 2 hours tops.

I didn't say that it would take too long.

I'm saying that doing it that way inherently builds error into the MAF curve, which screws up load calculation, etc. If there is an OEM calibration, which I'm sure there is, that is a more accurate way to go. I am using MU52 injectors on a Coyote, so there is no solid calibration data.

[caniggia]

Correct, having correct maf transfer will help you dial injectors much easier. here you have:

90.3319473266602 93.6180572509766 97.4883728027344 100.955497741699 103.716499328613 105.887298583984 108.264801025391 110.923400878906 112.40470123291 115.534202575684 119.11710357666 123.263496398926 134.057205200195 141.253402709961 150.274795532227 162.580703735352 180.09049987793 187.144805908203 192.617401123047 199.054397583008 206.664398193359 215.335601806641 225.130996704102 236.495697021484 250.141998291016 267.027709960938 276.985595703125 288.609100341797 316.512786865234 335.321899414063 359.344696044922 391.028686523438 413.428894042969 439.216400146484 475.810089111328 525.508117675781 610.398681640625 661.541198730469 711.511291503906 1400


680.388555
604.789826666667
529.191098333333
472.224660340968
430.557805688413
402.779892973834
375.001980259256
347.224038706051
333.335067929448
305.557126376244
277.779213661665
250.001300947086
194.445446679303
166.667533964724
138.889606830832
111.111686906597
83.3337669823621
75.0003917260572
69.4448106250728
63.8892151047753
58.3336340037909
52.7780492979782
47.2224645921655
41.6668834911811
36.1112987853684
30.5557140795557
27.7779217266493
25.000129373743
19.4445446679303
16.6667523150239
13.8889608633247
11.1111685104183
9.72227593879342
8.33337615751197
6.94448088226587
5.55558515641623
4.16668807875598
3.61112974335578
2.77779212760458
0.755987294598422

[CCS86]

Thanks Carniggia, that data matches the curve in the Roush-575 file in the repository. Do you have any hands on experience with it, or know for sure that it is intended for the housing I pictured?

Roush claims that the above data is not correct for this MAF housing (refusing to send the correct data), but I'm not sure how much I trust this claim.

Doing some rough math, comparing the open area of the GT500 vs the Roush housing, the percent difference is pretty close to the curve difference, which is promising.

[caniggia]

I have 2-3 files from roush 11-14 and i have 2 maf curves for this year. Hausing on photo is defintely 11-14 Roush phase 1 hausing 575
MAF above is with injector changed, could be this file was posted by txcharlie.

Bellow is second maf curve i have and this curve is same in 2 files, they have smaller values, so i bet it will be correct one.

514.071352666667
363.554285708545
312.502476923332
262.478794001694
229.366542916878
216.925718175517
194.171104828017
173.146333216731
157.800319688697
148.440974256127
136.077711
123.981911582804
98.2783468333333
78.5470813338097
71.8385391659748
65.0032223972513
60.8295089587846
57.4965820631025
51.9710652299584
47.9122520880318
46.1182480132931
43.1091933094397
41.3916656666235
38.5209534576035
31.7514644580687
26.8375481978505
23.1332104374206
19.8068659581745
15.1197456666667
14.2125608906184
11.1886119375265
7.8622674582804
6.46369141669313
5.06511492450232
4.38472611716434
3.73457708774355
3.56069999815757
3.29610447602711
3.11466761093816
0

83.3000030517578 101 107 114 119.800003051758 123 128 132 136 139 143.5 150 160.5 173 178 183.5 188 193 200 207 210 215.5 220 226 242 259 275 290 320 330 360 410 450 500 540 590 605 635 650 1485

[CCS86]

Interesting. Are you saying that you think the two different curves are for the same MAF housing, but with different injectors?

Why would injectors cause any change to the MAF curve? Do you know which injectors are used in each calibration?

[veeefour]

Interesting. Are you saying that you think the two different curves are for the same MAF housing, but with different injectors?

Why would injectors cause any change to the MAF curve? Do you know which injectors are used in each calibration?

Injectors can't affect Air Model - this is impossible. Must be something else.

[caniggia]

Since its few years I don't really remember, could be cai was changed, second one I have marked stock and fine tune I was doing, so I bet one is correct, injectors looks 47lb. First looks had 80lb injectors.

Btw, you can use gt500 data injectors into coyote no problem.

[CCS86]

Since its few years I don't really remember, could be cai was changed, second one I have marked stock and fine tune I was doing, so I bet one is correct, injectors looks 47lb. First looks had 80lb injectors.

Btw, you can use gt500 data injectors into coyote no problem.

I tried using the 2013 GT500 injector data and it was wayyyy off. I hoped that since it has multiplier tables for flow/breakpoint/offset vs rail pressure, using the higher Coyote inferred rail pressure tables would sort everything out. That was not the case.

Since then I have slowly tuned flow, BP and offset based off of logged data, and have it fueling pretty well. I still feel like there is room for improvement though.

Do you have some good #'s for MU52 injectors in a Coyote, you wouldn't mind sharing?

[caniggia]

Definitely wrong injector data affects maf model.

Ill look when im home, I should have gt500 data installed in coyote 15 when I was upgrading roush.

Send me your email pm

[veeefour]

If you swap the injectors only and if you have a correct injector data this change CAN'T affect fueling/air model in ANY WAY.

[caniggia]

That's correct, why correct data should affect. That's why ccs86 needs correct maf to setup injectors if he don't have or is not sure for injector data.

[veeefour]

Well the difference between wrong injector data and un-tuned MAF curve is clearly visible in data logs.

[CCS86]

Well the difference between wrong injector data and un-tuned MAF curve is clearly visible in data logs.

How so?

[tbrtuning]

The talk about injector data is kind of funny on a Coyote car without return fuel system... No fuel pressure compensation on these cars so it is a bit of a stretch to talk about perfect injector data on them.

[CCS86]

The talk about injector data is kind of funny on a Coyote car without return fuel system... No fuel pressure compensation on these cars so it is a bit of a stretch to talk about perfect injector data on them.

Is it?

Have you datalogged rail pressure and found significant differences compared to the inferred rail pressure tables?

Even if rail pressure varies somewhat, flawed injector calibration data will only make fueling worse. So, it's a silly argument to downplay its importance.

[tbrtuning]

True the difference is not big but when trying to get to get exact it makes a difference. Luckily these ECUs are fast and have widebands so it is not that big of a deal