marantzvieta
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« Reply #60 on: April 01, 2025, 01:59:11 PM »
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This is nuts, FR for M3.8, this man deserves heaven. Thank you for sharing this, I have been behind something like this for the last TWO years. Just for curiosit: is it possible to know where does this file come from? I love to know the stories behind such things..
doktor:
- I know I owe you an answer, I have been up to my head with work... will review the info I mentioned to you in the following days.
- Stock AGU injectors are rated for 242cc at 3Bar, use a 4Bar FPR from the A4 to push them a bit further, but you need to tell the ECU with FGAT0 the new factor.
- The axis that only go to "X"ms yes, if you go further the last values of the axis it will still use the last value. You can rescale the axis of the maps but need to take into account the other maps affected. Here in the FR or in a GOOD damos (558E floating around here) should allow you to see all maps attached to an axis and then consider if you need doing more work or not on other maps.
Also the info on the PID system is gold. Must thank all contributions, M3.8.x is slowly making more sense.
Best regards to all.
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doktor
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« Reply #61 on: April 01, 2025, 11:31:31 PM »
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- Stock AGU injectors are rated for 242cc at 3Bar, use a 4Bar FPR from the A4 to push them a bit further, but you need to tell the ECU with FGAT0 the new factor.
- The axis that only go to "X"ms yes, if you go further the last values of the axis it will still use the last value. You can rescale the axis of the maps but need to take into account the other maps affected. Here in the FR or in a GOOD damos (558E floating around here) should allow you to see all maps attached to an axis and then consider if you need doing more work or not on other maps.
Thanks, yeah, I might try this, just surprised how easily the original injectors are maxed out... A bit of maths, if the injectors are really precisely 242cc/min, I did some calculations and this comes to 13.9 AFR at 170g/s MAF. Not really good... Before I dig deep into the FR (and not even sure if such details are included), does anyone have an idea if the ECU knows the IDC is 100% so it does not request any more boost, or does it ignore it and easily leans out? |
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« Last Edit: April 02, 2025, 05:21:15 AM by doktor »
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overspeed
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« Reply #62 on: April 02, 2025, 06:27:19 AM »
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242cc/min with n-hepteno, wich has 0,683 specific gravity
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marantzvieta
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« Reply #63 on: April 02, 2025, 07:41:45 AM »
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Thanks, yeah, I might try this, just surprised how easily the original injectors are maxed out...
A bit of maths, if the injectors are really precisely 242cc/min, I did some calculations and this comes to 13.9 AFR at 170g/s MAF. Not really good...
Before I dig deep into the FR (and not even sure if such details are included), does anyone have an idea if the ECU knows the IDC is 100% so it does not request any more boost, or does it ignore it and easily leans out?
M3.8 has no DC recognition from what I know untill now, maybe there is something in the FR that indicates otherwise but haven't dug enough in it yet. 242cc/min with n-hepteno, wich has 0,683 specific gravity
How does this affect the recalculation of the factor? |
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overspeed
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« Reply #64 on: April 02, 2025, 10:06:43 AM »
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At same opening time it will flow some kind of (0,755/0,683) more g/s
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doktor
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« Reply #65 on: April 02, 2025, 12:12:08 PM »
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marantzvieta
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« Reply #66 on: April 02, 2025, 12:42:26 PM »
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My bad I was confused with A4 AEB injectors, although the data on my memory or that forum isn't precise either: 1g/min = 1,39cc/min AGU - 06a906031 - 0280150464 - 194g/min @3bar or 270cc/min @3bar AEB - 058133551 - 0280150447 - 168g/min @3bar or 234cc/min @3bar Considering AEB has 4bar FPR, that pumps AEB injector output to 270cc/min @4bar. I use this calculator for FPR changes: https://raceworks.com.au/calculators/injector-flow-vs-fuel-pressure/Hence, I was remembering correctly they had the same flow but incorrect on the precise data hah. I belive it isn't that bad to max out the injectors while they are available to provide enough fuel for the air entering the engine, you only have to see how many 1.8t's with stage 1 are running worldwide and not dying. But I am the kind of person that prefers to leave headroom when upgrading them. I use the rule of 100cc more than expected hp. Best regards, |
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doktor
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« Reply #67 on: April 02, 2025, 02:11:47 PM »
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Well, not sure if this is much OT, but I hope not. I did a bit more investigation into the injectors. I measure duty cycle directly on one of them. They consistently max out (100% IDC) at 140g/s, 4500rpm, 10ms "load".  At these conditions, the fuel enrichment according to KFLF i 1.29, which should translate to 11.4 AFR, so 12.3 g/s fuel. For one injector this is 185g/min. Hmm, actually this is close to what marantz posted, a bit on the low side. If they max out at 140g/s, it looks like running 170g/s is asking for trouble. This looks like a job for 4bar FPR even for "stage 1"... |
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marantzvieta
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« Reply #68 on: April 03, 2025, 01:35:42 AM »
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Well, not sure if this is much OT, but I hope not. I did a bit more investigation into the injectors. I measure duty cycle directly on one of them. They consistently max out (100% IDC) at 140g/s, 4500rpm, 10ms "load". At these conditions, the fuel enrichment according to KFLF i 1.29, which should translate to 11.4 AFR, so 12.3 g/s fuel. For one injector this is 185g/min. Hmm, actually this is close to what marantz posted, a bit on the low side. If they max out at 140g/s, it looks like running 170g/s is asking for trouble. This looks like a job for 4bar FPR even for "stage 1"... Are you sure your DC measuring system is correct? I am moving 170g/s air at 6200rpm and I have no symptoms of running lean with stock injectors (A4 with 4bar fpr so same flow as yours). |
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doktor
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« Reply #69 on: April 03, 2025, 01:55:14 AM »
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Are you sure your DC measuring system is correct? I am moving 170g/s air at 6200rpm and I have no symptoms of running lean with stock injectors (A4 with 4bar fpr so same flow as yours).
Yes I am, I work with electronics so I know what I am doing... I actually had two circuits, one which displayed a value directly, and another one which lights up an LED if the IDC is above 97%, so it does not distract me from driving at high speeds. Both were consistent. I reliably hit 100% above 4500rpm and compared this with logs I was doing simultaneously. The 140g/s figure at which this happens was replicated more times. How are you sure about "not running lean"? I also had no "symptoms" at 170g/s, but I don't have a wideband so don't know... Also, there are still mixed signals about stock injector size on the AGU. Actually I found 4 values - 205, 240, 270 and 285cc... Could this be manufacturer specific? Guess I will have to take a look at them directly  btw, is the OEM fuel pump fine with 4bar FPR? From what I found, it most likely is... |
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overspeed
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« Reply #70 on: April 03, 2025, 06:25:05 AM »
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My bad I was confused with A4 AEB injectors, although the data on my memory or that forum isn't precise either: 1g/min = 1,39cc/min AGU - 06a906031 - 0280150464 - 194g/min @3bar or 270cc/min @3bar AEB - 058133551 - 0280150447 - 168g/min @3bar or 234cc/min @3bar Considering AEB has 4bar FPR, that pumps AEB injector output to 270cc/min @4bar. I use this calculator for FPR changes: https://raceworks.com.au/calculators/injector-flow-vs-fuel-pressure/Hence, I was remembering correctly they had the same flow but incorrect on the precise data hah. I belive it isn't that bad to max out the injectors while they are available to provide enough fuel for the air entering the engine, you only have to see how many 1.8t's with stage 1 are running worldwide and not dying. But I am the kind of person that prefers to leave headroom when upgrading them. I use the rule of 100cc more than expected hp. Best regards, those values are consistent with KVB values on both files (18CG 261cc/min and 558E 267cc/min), but again... don´t forget Bosch state flow with diferent specific gravity |
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« Last Edit: April 03, 2025, 06:34:28 AM by overspeed »
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doktor
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« Reply #71 on: April 03, 2025, 08:58:10 AM »
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Well I still come to the conclusion that my findings seem correct. If I use 261cc/min and 0,75g/cm3 fuel, this comes to 13g/s fuel (for 4 injectors), for AFR 11.4 (from KFLF though there might be other multiplicative factors which probably contribute to the error) I get really only 149g/s air. The most precise number I can come to when I hit 100%DC is 142g/s. Considering a lot of uncertainities this is quite spot on. 4bar FPR ordered already |
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overspeed
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« Reply #72 on: April 03, 2025, 09:06:30 AM »
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Well I still come to the conclusion that my findings seem correct. If I use 261cc/min and 0,75g/cm3 fuel, this comes to 13g/s fuel (for 4 injectors), for AFR 11.4 (from KFLF though there might be other multiplicative factors which probably contribute to the error) I get really only 149g/s air. The most precise number I can come to when I hit 100%DC is 142g/s. Considering a lot of uncertainities this is quite spot on. 4bar FPR ordered already Those MAF reading´s tend to get lower as the sensor ages, or even get dirt take that with grain of salt Even specific gravity varies... 0,715 ~0,755g/cc |
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