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Discussion Starter · #1 ·
Since I'm still waiting on my chip (hint, hint), do you have a version that will use a converted wideband output (e.g. http://www.wmsracing.com/wmsweb/wideband.htm) and just use this input instead of MAP at higher RPM (run in closed loop mode all the time like newer systems)? That is something I'd really like to have so that changes in the engine or boost configuration don't need a new chip.



Modified by hallkbrd at 6:29 AM 3-17-2006
 

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Discussion Starter · #2 ·
Re: SNS guys - Wideband question (hallkbrd)

I'll try and give Mr. Watts a call again today and post how it goes.
 

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Re: SNS guys - Wideband question (KeithMac)

Why? Of course you would need to compare the value from the sensor to a reasonable range for the RPM, and ignore it if it's out of that range.
But, like newer vehicles, I can't see any reason why you can't run the digi 1 in this mode, other than just nobody has a chip to do it.
The idea is to not have to run overly rich, but to understand exactly what the engine wants (from the O2 sensor input) and provide the best mixture to produce the most power at any engine speed and load. IOW, adjust the amount of fuel injected based on the AFR table until the sensor reports a voltage corresponding to the air/fuel ratio in the appropriate cell of the AFR table (for wide band).
Possibly using megasquirt-II would be a better way to go for less $$ but more work on my part.


Modified by hallkbrd at 8:24 AM 3-18-2006
 

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Re: SNS guys - Wideband question (hallkbrd)

You can`t loose the map reading and base it soley on rpm and wideband output really, you can have vastly different fuel requirements at the same rpm full load or cruise and the ECU only has MAP to go by to differenciate.
I still think you can`t beat a good solid map from the start, plus only the SNS guys will know if the ecu`s got enough left to sense the wideband signal and correct fueling quiclky enough.
Also if you only give the correction +/-10 say from a set table (so if the sensor miss-reads you`re not dangerously lean) you`re not gaining a lot?
 

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Discussion Starter · #6 ·
Re: SNS guys - Wideband question (KeithMac)

Quote, originally posted by KeithMac »
Also if you only give the correction +/-10 say from a set table (so if the sensor miss-reads you`re not dangerously lean) you`re not gaining a lot?

True enough, but the idea was to be able to change boost, flow, or fuel pressure and injector configurations without having to change the chip everytime.
Based on a set table, the fi pulse width is very dependant on a known or measured boost, fuel pressure, injector size, and a known flow at a given RPM. If you change either the flow amount (port the head, change to a 16v head, etc.) or change the boost pressure (pulley), you need a new chip to stay somewhat close to optimal under open loop (table) mode. Now possibly the SnS chips can well adjust enough to boost pressure changes (within a certain range), but there is nothing (I'm aware of) that will adjust to the flow. The only way I know to adjust for that is to use a wideband O2 sensor and actually detect what's happening real-time.
True, the old digi 1 may not have enough cycles to do this, so the question may be moot. I know they were working with wideband a few years ago - but back then, WB sensors were a lot more expensive.
 

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Re: SNS guys - Wideband question (hallkbrd)

we would need another 5v input in order to do it correctly with a wideband... I wouldn't replace the map input with the wideband because that would turn the system into a reactive system instead of a pro-active system and I'm afraid the ECU would not be able to react fast enough for the wide range of load and rpm it would have to deal with.
 

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Re: SNS guys - Wideband question (jwatts)

If you had enough room for a 2nd table you could use this to store a modified fuel table based on the wideband input and estimated corrected values, then update the main table periodically. There is also a problem with the speed at which the 02 sensor works, the maths to convert this into a correction factor and then apply it to the injector pw`s, not much time when the engines spining at 6k or more.
Also look what problems the normal digi1 has when the narrowband O2 sensor starts to fail, luckily it is only used in closed loop not on boost so can`t do any damage, imagine what estimated values the ecu would come up with if the wideband went out of calibration.
 

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Discussion Starter · #9 ·
Re: SNS guys - Wideband question (jwatts)

Quote, originally posted by jwatts »
I'm afraid the ECU would not be able to react fast enough for the wide range of load and rpm it would have to deal with.

OK, trying to push the edge too far with old hardware. Good enough.
Then I'll just be content with the MAP for now, and put the Ultramegasqurt in somewhere down the road (so to speak).
 

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Re: SNS guys - Wideband question (hallkbrd)

If it's any consolation... Digi 1 works much better with any of the extra injector controllers in conjunction with our chips. Not having to worry about the O2 circuit battling for control will allow any EIC to do its job above the magical 1bar of boost, or even beforehand.
 
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