M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine management => Topic started by: bearsbmw on November 24, 2008, 12:43:42 AM
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Im sure AFM Controls Injector duty cycles so then a fully open AFM door flap would be 100% duty cycle ?
Does the O2 sensor signal also have influence over duty cycle when in WOT
The reason I ask is I have a very intresting idea im going to try with a 02 simulator, bigger injectors, and some afm door figeting and my 12psi of boost and my crude tune
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I believe O2 readings are tossed at WOT.
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I believe O2 readings are tossed at WOT.
Ahhh yes stupid me ... back to the drawing boards
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Also injector duty cycles are usually indexed with TPS and engine speed as well.
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so I would need to find a stock fuel map to actulay know 100% correct?
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anybody know where I could find a map?
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I remember reading somewhere that WOT was like 105 or 110%?
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I remember reading somewhere that WOT was like 105 or 110%?
Sweet! some insurance would be nice and it would realy help with my injector selection
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I remember reading somewhere that WOT was like 105 or 110%?
I'm not so sure about this. If your talking about duration of opening it is impossible to have more than 100%:confused:. Even 100% open is very bad as your injector never closes:(.
I know for MoTec they recommend no more than 80% IJPU. Over that the injector gets inefficient and can cause more problems than it's worth.
I know when we had IJPU on the E30 M3 that was at 82%-83% across 4 cyl's we got some weird readings from the ECU.
When we changed to bigger injectors problems went away.
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Over about 80% duty cycle, injectors start to lose accuracy. At 100% the injector essentially stays open continuously and can be damaged.
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Perhaps I am confusing this figure for something else, I anticipate the actual figure :)
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Perhaps I am confusing this figure for something else, I anticipate the actual figure :)
it's killing me haha
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I think I was confusing the 105/110% number for the TPS figure at WOT, not injector duty cycle, now that I think about it :)
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I might be on to something so fantastic and cheap you will all be looking for a AFM driven car forever :P will keep updating
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The injector duty cycles are controlled by (in no particular order):
AFM (primarily)
Intake Air Temp.
Coolant Temperature (warm-up enrichments)
Throttle Position
Exhaust Gas Oxygen Content*
*The O2 sensor's input is only used below 85% throttle & 4000RPM, if I recall correctly.
Keep in mind that the AFM's signal is the load-variable's primary input, and that ignition timing is directly affected by the ECU's computed load value at a given instant. Tweaking it might cost you some performance due to incorrect ignition timing, or a whole motor.
What exactly are you working on here? I saw evidence of boost......
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The injector duty cycles are controlled by (in no particular order):
AFM (primarily)
Intake Air Temp.
Coolant Temperature (warm-up enrichments)
Throttle Position
Exhaust Gas Oxygen Content*
*The O2 sensor's input is only used below 85% throttle & 4000RPM, if I recall correctly.
Keep in mind that the AFM's signal is the load-variable's primary input, and that ignition timing is directly affected by the ECU's computed load value at a given instant. Tweaking it might cost you some performance due to incorrect ignition timing, or a whole motor.
What exactly are you working on here? I saw evidence of boost......
well the idea is cheap and simple ... I plan to falsely send a signal to the ecu from both knock senors and using a map sensor and a small home made computer for anything over 8psi with correct size injectors afm ajustment not sure if it will work or not but I like to mess around
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well the idea is cheap and simple ... I plan to falsely send a signal to the ecu from both knock senors and using a map sensor and a small home made computer for anything over 8psi with correct size injectors afm ajustment not sure if it will work or not but I like to mess around
Good stuff, experimenting is always fun stuff. When you say homemade computer, are you talking about using a microcontroller & some custom code or something, or Megasquirt / etc? I am all about custom microcontroller apps!
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Good stuff, experimenting is always fun stuff. When you say homemade computer, are you talking about using a microcontroller & some custom code or something, or Megasquirt / etc? I am all about custom microcontroller apps!
yes microcontroller and someone to right me a Mini App for it with USB connection... I was thinking maybe use a old black berry and flash it with new software ...I realy have no idea what im doing but I have all winter to screw around ... the reason I started all this stuff is that buddy is runing 14psi on a m42 stock internals and 2 extra injectors in the intake and no spark tune and the motor run's fine when boosting... It's starting to get to me and I need to find out why the ECU is allowing for it and it's not like he's been driving around for a day or two this way... he has been in the that range for a few years
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yes microcontroller and someone to right me a Mini App for it with USB connection... I was thinking maybe use a old black berry and flash it with new software ...I realy have no idea what im doing but I have all winter to screw around ... the reason I started all this stuff is that buddy is runing 14psi on a m42 stock internals and 2 extra injectors in the intake and no spark tune and the motor run's fine when boosting... It's starting to get to me and I need to find out why the ECU is allowing for it and it's not like he's been driving around for a day or two this way... he has been in the that range for a few years
Very interesting. I haven't heard of 14psi on stock internals on the M42 before, but I'll take your word for it. Has your friend dyno'ed it or anything yet?
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Very interesting. I haven't heard of 14psi on stock internals on the M42 before, but I'll take your word for it. Has your friend dyno'ed it or anything yet?
no dyno yet... faster then my 8psi for sure...I need to see a m42 stock ignition map to figure things out
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have you asked your friend what he uses?
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have you asked your friend what he uses?
what should I be asking?
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well after talking to a good friend of mine and figuring out how to do a crude tune with almost zero budget we figured it out and it's so very simple! using 36# injectors I'm able to control idle with AFM ajustment...Next thing is the TPS.. we all know that when your on half throtle your car will start to boost and the ECU does not like it at all and you can see knock very easly on hot days so to get around this we wired a 1psi boost activated On/off switch on the signal line for the TPS therefor tricking the ECU and making it think its in WOT postion when your only half... were still working on ECU adaptation
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interesting, good update :)
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I need to find a away to simulate the electrical fluctuation of a normal cycle o2 sensor and keeping the ECU happy ... Not sure how this will be done yet but will take any suggestions ... thanks!
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I need to find a away to simulate the electrical fluctuation of a normal cycle o2 sensor and keeping the ECU happy ... Not sure how this will be done yet but will take any suggestions ... thanks!
I'm trying to do that with the analog output from my wideband (innovate lc-1), but until now I get only ground issues and the value that ecu see goes negative, thus ecu show the error about the wrong voltage...
you need to trick the heater system of the lambda sonde otherwise it will show the error for that too.
there are some circuits that plug directly on the lambda connector, search with google for "o2 simulators"... be careful, not all simulate the fluctuation (some send a fixed voltage)... ECU is not happy with a fixed voltage, it needs the fluctuation.
I'll try more in next days to solve my problem with a multimeter! :)
tricking the TPS will change the load that the ECU sees so it will change ignition timing too... you need to check HOW MUCH :D
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I'm trying to do that with the analog output from my wideband (innovate lc-1), but until now I get only ground issues and the value that ecu see goes negative, thus ecu show the error about the wrong voltage...
you need to trick the heater system of the lambda sonde otherwise it will show the error for that too.
there are some circuits that plug directly on the lambda connector, search with google for "o2 simulators"... be careful, not all simulate the fluctuation (some send a fixed voltage)... ECU is not happy with a fixed voltage, it needs the fluctuation.
I'll try more in next days to solve my problem with a multimeter! :)
tricking the TPS will change the load that the ECU sees so it will change ignition timing too... you need to check HOW MUCH :D
Intresting!! I didn't know there was sims with fluctuations... thought they were all fixed ! either way you look at it, the TPS trick is better then what was going down befor and at WOT the computer would retard the timing by default I would think/hope lol ... I could be wrong ! I wish I could see some Fuel and Ign map's for this motor GRRR!