C32 FUEL INJECTOR UPGRADE
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Joined: Jun 2013
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"World fastest" C32 AMG
But if i do that, tank has several litres gas in bottom, but pump run out way earlier... Becouse my pump suction is not all the way down(different pump, not stock), so i dont like that idea 
I put one walbro to refill the sump, then my fuel lights and gauges works normal.
I put one walbro to refill the sump, then my fuel lights and gauges works normal.
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From: New Zealand
Are you talking theory here or you actually know how the ME2.8.1 is programmed? If according to EPC you can go from 396cc to 542cc then the ECU will adjust. If you have to bring the car to the dealer for an updated ECU file, then this is good news since it means that you can get an OEM ECU file for the 550cc injectors. However, I never heard of this OEM file to exist.
Since I am fairly sure our cars don't have wideband oxygen sensors there is no way they can adjust fuel trims in open loop mode (ie reading injector duty for the appropriate ms of injector opening times directly from the ecu tables). In closed loop mode (ie using the narrowband oxygen sensor for AFR correction) while cruising at light throttle there will be the ability to adjust the fuel trims to a minor degree based on this feedback.
So if you change the injector size, when you floor it the ecu will be using the same amount of injector opening time and if you double the size of the injector you inject twice as much fuel with all other variables (ie fuel pressure, ecu tune) being constant. I can't explain increasing the injector size so much and having no ill consequences.
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Joined: Jun 2013
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"World fastest" C32 AMG
I do not know the specifics of the Bosch ME2.8 so yes I could certainly be wrong. I am applying theory based on the fact that almost every EFI production car since the 80's works on the same principles of fuel injection and ecu control using rpm, throttle opening % and MAF or MAP values to find ignition and injection values from look up tables.
Since I am fairly sure our cars don't have wideband oxygen sensors there is no way they can adjust fuel trims in open loop mode (ie reading injector duty for the appropriate ms of injector opening times directly from the ecu tables). In closed loop mode (ie using the narrowband oxygen sensor for AFR correction) while cruising at light throttle there will be the ability to adjust the fuel trims to a minor degree based on this feedback.
So if you change the injector size, when you floor it the ecu will be using the same amount of injector opening time and if you double the size of the injector you inject twice as much fuel with all other variables (ie fuel pressure, ecu tune) being constant. I can't explain increasing the injector size so much and having no ill consequences.
Since I am fairly sure our cars don't have wideband oxygen sensors there is no way they can adjust fuel trims in open loop mode (ie reading injector duty for the appropriate ms of injector opening times directly from the ecu tables). In closed loop mode (ie using the narrowband oxygen sensor for AFR correction) while cruising at light throttle there will be the ability to adjust the fuel trims to a minor degree based on this feedback.
So if you change the injector size, when you floor it the ecu will be using the same amount of injector opening time and if you double the size of the injector you inject twice as much fuel with all other variables (ie fuel pressure, ecu tune) being constant. I can't explain increasing the injector size so much and having no ill consequences.
And if your fuel trims adjusts too much, it can cause problems.
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2002 C32 AMG, 2013 GLK 350/4, 2015 E63S AMG Wagon
I do not know the specifics of the Bosch ME2.8 so yes I could certainly be wrong. I am applying theory based on the fact that almost every EFI production car since the 80's works on the same principles of fuel injection and ecu control using rpm, throttle opening % and MAF or MAP values to find ignition and injection values from look up tables.
Since I am fairly sure our cars don't have wideband oxygen sensors there is no way they can adjust fuel trims in open loop mode (ie reading injector duty for the appropriate ms of injector opening times directly from the ecu tables). In closed loop mode (ie using the narrowband oxygen sensor for AFR correction) while cruising at light throttle there will be the ability to adjust the fuel trims to a minor degree based on this feedback.
So if you change the injector size, when you floor it the ecu will be using the same amount of injector opening time and if you double the size of the injector you inject twice as much fuel with all other variables (ie fuel pressure, ecu tune) being constant. I can't explain increasing the injector size so much and having no ill consequences.
Since I am fairly sure our cars don't have wideband oxygen sensors there is no way they can adjust fuel trims in open loop mode (ie reading injector duty for the appropriate ms of injector opening times directly from the ecu tables). In closed loop mode (ie using the narrowband oxygen sensor for AFR correction) while cruising at light throttle there will be the ability to adjust the fuel trims to a minor degree based on this feedback.
So if you change the injector size, when you floor it the ecu will be using the same amount of injector opening time and if you double the size of the injector you inject twice as much fuel with all other variables (ie fuel pressure, ecu tune) being constant. I can't explain increasing the injector size so much and having no ill consequences.
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Joined: Aug 2011
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From: New Zealand
I can't explain it either and just in case, had EC create me a tune for larger injectors and am monitoring AFRs, IDC, and all kinds of other things. Can't stress enough the importance of monitoring/data logging when you start modifying your car, especially things like fuel delivery.
For the OP, just out of interest, why are you looking to change your injectors? Are you approaching the limits of what they can flow?
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From: New Zealand
It's been a while since I have wired in and tuned an aftermarket ecu (and read my tuning books) but why do you want to see those things specifically? Injector duty cycle as a % is very useful to determine the time the injectors are spending open. You definitely want this less than 90% at WOT to keep using the current injectors safely. I don't think pulse width is going to help much with tuning. I have found a lot of ecu's instead use arbitrary numbers to represent the injection times on the fuel tables.
Fuel pump duty cycle? As far as I am aware the only way to find out the limits of your fuel pump is to measure the fuel pressure on the dyno. The pump is always running at 100% and the fuel pressure regulator is controlling how much goes back into the tank. Of course this is easier said than done. If you have the original pump or you are planning some serious upgrades then it is always a good idea to upgrade regardless.
I agree long term fuel trims are useless and from what I remember only give you an idea on what is happening in closed loop mode. For tuning- datalogging rpm, wideband AFR's, knock, ignition timing, MAF/MAP/AFM (MAP in your case, MAF in mine and hopefully no one uses AFM's anymore) and throttle response should be all you need. Compare the target AFR's with the actual AFR's on the load vs RPM table and adjust fuel amounts accordingly until they match. Lots of fun, and have replacement wideband sensors and spark plugs ready.
Thread Starter
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Joined: Mar 2015
Posts: 107
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From: Australia
E250 cdi
+1 absolutely. For most projects simply putting a larger fuel pump, some larger injectors and a good tune is a good recipe to support a reliable increase in power. We are lucky being able to datalog via the OBD2 port.
For the OP, just out of interest, why are you looking to change your injectors? Are you approaching the limits of what they can flow?
For the OP, just out of interest, why are you looking to change your injectors? Are you approaching the limits of what they can flow?
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Joined: May 2013
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2002 C32AMG
Did you ever get enough fuel added to the car and get back to the dyno?
