Quote:
Originally Posted by Nerys
its fuel injected?? I am curious what more fuel pressure would do and how in the world would I alter that? another pump inline or something??? and why would E10 need more fuel pressure than E0 (just curious)
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Quote:
Originally Posted by Nerys
Ahh ok I am no genius at auto mechanics so bear with me but would not lower mpg mean I am running RICH not LEAN?
running richer would use more fuel would it not?...
I also thought the injector controlled the pressure of each squirt ultimately? ie the Metro uses a recirculating fuel system it just cycles from the tank to the engine and back to the tank and the injector "takes" what it needs for each pulse.
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Quote:
Originally Posted by Nerys
"...A richer mix nets better fuel economy during acceleration and depending on how lean you are potentially during cruise."
a richer mix by every measure I could find worsens fuel economy. including the link DCB provided. If the car is running lean which fraks with the ECU causing it to "richen" ok that makes sense. but if the fuel pressure is FINE (I have not tested it yet) I see no reason to muk with fuel pressure or temperature.
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Quote:
Originally Posted by Nerys
what I am unsure about is the why. if its already adding too much fuel why would I want it to add more? ie how could adding more fuel result in better fuel economy? (it runs smoothly on E10 thats not an issue)
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To clarify and answer some of the above while trying not to forget anything I wanted to post.
Yes fuel increasing pressure can richen the mixture if it is needing fuel, if it has enough fuel and pressure is increased it will use the same amount of fuel to reach stoich as long as the ECU has enough room to cut fueling.
Assuming that the car is currently able to run at stoich with e10 and pressure in increased by say 5%. The cars ECU should be closer to having the fuel trims at 0 allowing for more adjustments and less likely to max out the adjustment. With that said increasing the fuel pressure can have a few added effects it increases the amount of flow in the injectors by doing that the time they have to be open. If the fuel is being sprayed/closed to late in the rotation it may not have enough time to disburse and burn leading to an incomplete burn a late burn (still burning as exhaust opens) one case it will think the car is running fine the other it will think it is rich. Both will lead to not extracting all the available energy.
Look into finding an adjustable FPR (fuel pressure regulator).
As for richer mix creating better FE is possible as there is more power potential from running rich and completely burning the mixture I believe the AFR for e0 that is best is ~13.8 (will have to check to be sure). If you are generating more power at a lower throttle position(TP) than a higher TP at stoich you can save fuel when accelerating, as long as the extra percent of fuel when rich is less than the increased percentage of air consumed at the higher TP. Running leaner it is more likely to have knock and I will assume that the metro has a knock sensor if it does you should not hear the knock as the car will adjust before it gets to that point. The knock sensor will reduce timing and reduce efficiency, this can go back to the last paragraph if the fuel is not burning at the right time or has some fuel pooling and burning late it can think it is knocking and reduce timing.
The O2 sensor reads the amount of O2 in the pipe and uses that to determine if the engine is at stoich or Lambda of 1, it should be accurate to adjust for all fuels.
Sorry I'm not sure about the ignition system but check out
RockAuto Auto Parts for parts numbers then look at what other vehicles can use it and see if they have a hotter ignition system that you could use of an upgraded part that is not listed.
I know that I forgot some of what I was going to saw but I will eventually remember.