VEMS install Porsche 911 Carrera 3,2 170kW/231PS motorcode 930-20, help needed
05-16-2014, 04:40 PM
#31
When you say injector groups what do you mean? The stock setup has inj 1-3 wired together and then 4-6 wired together so this looks like 2 groups from just looking at the wiring. BUT! that's not how they work! In the DME those 2 wires goto the same exact place! All 6 injectors are actually wired together in parallel and they are all fired by one large Darlington transistor.
If your EFI allows for 2 groups that's fine but the 2 groups simply both need to fire at same time and once per crank rev. Of course converting to true sequential may help lower load and lo RPM but at WOT it won't matter since the pulse widths are so wide anyway.
You also mentioned CLT/Fuel table I sent did not work? Do you mean the cold start CHT fuel Comp table? I think your numbers somehow start at 100% and my Table starts at 0% I think your table is very close to mine if you add 100 to my numbers, hope that makes sense. I'm not sure why they start at 100% since that does not make sense? Once warm the extra fuel needed is really 0% why would they say 100%, no matter I just think you can add 100 to my values and try that.
If your EFI allows for 2 groups that's fine but the 2 groups simply both need to fire at same time and once per crank rev. Of course converting to true sequential may help lower load and lo RPM but at WOT it won't matter since the pulse widths are so wide anyway.
You also mentioned CLT/Fuel table I sent did not work? Do you mean the cold start CHT fuel Comp table? I think your numbers somehow start at 100% and my Table starts at 0% I think your table is very close to mine if you add 100 to my numbers, hope that makes sense. I'm not sure why they start at 100% since that does not make sense? Once warm the extra fuel needed is really 0% why would they say 100%, no matter I just think you can add 100 to my values and try that.
05-16-2014, 04:46 PM
#32
Track Day
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Yes the wording is a bit strange in the vems editor.
Actually I´m firing all 6 injectors at once now every crank rev.
Regarding the table. Yes I meant the CHT fuel Comp table.
I allready interpreted the values to 100 and greater.
I updated the above thread a bit right when you were answering ;-)
Everything else seems to be working. But the warmup behaviour seems to be different.
Actually I´m firing all 6 injectors at once now every crank rev.
Regarding the table. Yes I meant the CHT fuel Comp table.
I allready interpreted the values to 100 and greater.
I updated the above thread a bit right when you were answering ;-)
Everything else seems to be working. But the warmup behaviour seems to be different.
05-16-2014, 04:57 PM
#33
email me sal.carceller@***.net and I'll send you a trace of what my warmup looks like in my setup, you'll see AFR, AirFlow, CHT all graphed in real time. It will give you an idea of where the AFR should be at the given Temp.
Also, if you are going to keep doing batch injection you will benefit from firing every crank rev. And if your EFI supports firing every 1/2 crank rev at higher pulse widths that's even better! The idea is to spread the fuel around as much as possible over the cycle time. Consider this: in the old CIS cars the injectors where always on the entire time, they never shut off, neither do carbs. But EFI injectors can't vary flow rate, they flow at a given rate so you can only control how long they are on for.
Also, if you are going to keep doing batch injection you will benefit from firing every crank rev. And if your EFI supports firing every 1/2 crank rev at higher pulse widths that's even better! The idea is to spread the fuel around as much as possible over the cycle time. Consider this: in the old CIS cars the injectors where always on the entire time, they never shut off, neither do carbs. But EFI injectors can't vary flow rate, they flow at a given rate so you can only control how long they are on for.
05-17-2014, 03:33 PM
#34
Race Car
Kudos scarceller for being so forthcoming and helpful - great example of the RL/Porsche community.
I've been luke-warm on the chip tuning biz for a long time but my experience was based in the early years. Things have come a long way and my views are shifting as well. I am now convinced that (proper) contemporary fuel management is attainable for older cars where it has not been before. This should result in improved output/driveability while reducing fuel consumption as well as increasing the life of these expensive engines...an all around winner. Kudos again.
I've been luke-warm on the chip tuning biz for a long time but my experience was based in the early years. Things have come a long way and my views are shifting as well. I am now convinced that (proper) contemporary fuel management is attainable for older cars where it has not been before. This should result in improved output/driveability while reducing fuel consumption as well as increasing the life of these expensive engines...an all around winner. Kudos again.
05-18-2014, 01:54 PM
#36
"Things have come a long way and my views are shifting as well. I am now convinced that (proper) contemporary fuel management is attainable for older cars where it has not been before."
Please explain what's meant by this statement.
Please explain what's meant by this statement.
05-19-2014, 12:09 PM
#37
The stock 84-89 DME system works very well but once you make air flow changes to a motor that significantly change Air Flow then you really need to re-tune. The other issue is the AFMs are getting old and replacements are very costly, if the AFM fails it is nice that other alternatives may be available such as MAF drop ins.
