Liquid LPG tune using Flex Fuel

[Wrath23]

Im looking into using the flex fuel system to change the fuel and spark maps to suit a Liquid LPG setup on an E38 controlled LS2.
I have only recently discovered the flex fuel so im not sure exactly how it effects engine operation, does it only adjust fuel and spark maps? or is there other changes made.
how much control over the system do I have with EFIlive? can I see and adjust all tables and modifiers related to flex fuel? can I use the fuel composition sensor input as a switch? can I use the input to sense LPG temp and modify the fuel map accordingly?

I been searching for as much info as I can find on flex fuel but there is next to nothing available. can anyone point me in the direction of somewhere or someone who knows the ins and outs of the system and its capabilities.

thanks

[gmh308]

Im looking into using the flex fuel system to change the fuel and spark maps to suit a Liquid LPG setup on an E38 controlled LS2.
I have only recently discovered the flex fuel so im not sure exactly how it effects engine operation, does it only adjust fuel and spark maps? or is there other changes made.
how much control over the system do I have with EFIlive? can I see and adjust all tables and modifiers related to flex fuel? can I use the fuel composition sensor input as a switch? can I use the input to sense LPG temp and modify the fuel map accordingly?

I been searching for as much info as I can find on flex fuel but there is next to nothing available. can anyone point me in the direction of somewhere or someone who knows the ins and outs of the system and its capabilities.

thanks

Do you have EFILive? If not download a demo at www.efilive.com.

And then take a look at a Flex Fuel calibration '08 5.3 litre truck at www.holdencrazy.com. EFILive has probably better access to FF control than any package and enables FF to be enabled/disabled and fuel, spark and transient tables to be adjusted.

Fuel composition sensor produces a frequency and pulse width modulated output the ECM uses to calculate ethanol content and temp. You would need to build a sensor which replicates the ethanol function for LPG.

Cheers.

[Wrath23]

Thanks gmh308.

This should work out perfectly for LPG. Now I just have to implement it.
Activating the FF is the only problem. Does anyone have a specs on the output of the fuel comp. Sensor? Is it possible to use a switch combined with a NTC thermistor without major software changes?

[gmh308]

Thanks gmh308.

This should work out perfectly for LPG. Now I just have to implement it.
Activating the FF is the only problem. Does anyone have a specs on the output of the fuel comp. Sensor? Is it possible to use a switch combined with a NTC thermistor without major software changes?

There is info on specs of the FF sensor outputs here:

http://www.megamanual.com/flexfuel.htm

As mentioned, it uses a frequency and pulse width modulated output, so that is what the ECM expects to monitor, so an NTC setup wont do it. A purpose built FF simulator would give you manual control of temp and ethanol content.

Of course the other catch here is whether there are any E38 operating systems that support connection of a hard FF sensor to the ECM and which pinouts the sensor uses. GM switched to virtual fuel sensing at some point on E38 with no hard sensor (IIRC '06) and they are still using the Virtual Sensor for '09.

:)

[Wrath23]

I am fairly confident my 09 VE SS commodore uses the virtual system as there is no part listing for a fuel composition sensor. However I install these liquid LPG systems on many gen4 vehcles so I will need to work out something for both types.

How does the virtual system pick up when there is ethenol present? What activates the FF tables?

[gmh308]

I am fairly confident my 09 VE SS commodore uses the virtual system as there is no part listing for a fuel composition sensor. However I install these liquid LPG systems on many gen4 vehcles so I will need to work out something for both types.

How does the virtual system pick up when there is ethenol present? What activates the FF tables?

Your '09 Commodore supports Flex Fuel from the factory?

In simple terms the virtual sensing system looks at what it needs to do in terms of degree of trim to keep the mixture in stoich, using a change in tank level as a trigger to consider trim changes as a change in fuel composition.

[Wrath23]

All I know so far is that I can run E10 in my commodore, I havnt been able to confirm if it has flex fuel or not, but a few sources believe they do run FF.

If they don't run FF is I possible to update the E38 with a OS that will support a virtual or sensor FF system?

[macca_779]

All I know so far is that I can run E10 in my commodore, I havnt been able to confirm if it has flex fuel or not, but a few sources believe they do run FF.

If they don't run FF is I possible to update the E38 with a OS that will support a virtual or sensor FF system?

VE's don't run Flex Fuel compensation as yet I believe. The fact that Holden say you can run E10 is only the case because it is in the scope of the fuel trims to add enough fuel to compensate for it (E10 is only 0.6:1 richer stoich). In fact I would surmise that you wouldn't find many Closed Loop EFI setups that can't work on E10.

E85 on the other hand which determines true flex fuel capability is way out of the scope of normal closed loop setups.

[gmh308]

All I know so far is that I can run E10 in my commodore, I havnt been able to confirm if it has flex fuel or not, but a few sources believe they do run FF.

If they don't run FF is I possible to update the E38 with a OS that will support a virtual or sensor FF system?

As Macca779 notes, E10 fits within the normal trim range and is not really considered Flex Fuel.

Remote chance the native E38 operating system in your VE coincidentally supports virtual sensor flex fuel. Any other OS is unlikely to be compatible with the rest of the car (BCM/Instrument panel/etc).

[Chevy366]

Back in the 70s we had a Ford 360 ci. truck running on LPG .
After seeing this did some research on now a day LPG , seems they are several people running LPG , off road of course (most with carburetor) , saying it has a 100 to 110 octane rating .
Which kit do you use ?
I found a good source for the kits but it is on my other laptop .

[Wrath23]

I had a look at the tune on the VE last night and it does support calculated flex fuel but it is not enabled from factory. So now the question is how to activate FF tables when I switch to lpg. When running on LPG the PCM sees no difference, the fuel trims hardly move and the o2 sensors see no difference. I think a modified os system to activate the FF or changing to the composition sensor pickup may be my only options.

[Wrath23]

Back in the 70s we had a Ford 360 ci. truck running on LPG .
After seeing this did some research on now a day LPG , seems they are several people running LPG , off road of course (most with carburetor) , saying it has a 100 to 110 octane rating .
Which kit do you use ?
I found a good source for the kits but it is on my other laptop .

The system I use are all liquid LPG systems. There is a couple of systems in Australia the most available being JTG made by icom. But there is another soon to hit the market that is said to be much better.

If your going to covert to LPG I wouldn't even bother with the old vapour systems. Do a search for liquid LPG Injection and you will see why liqud is so much better.

[Chevy366]

The system I use are all liquid LPG systems. There is a couple of systems in Australia the most available being JTG made by icom. But there is another soon to hit the market that is said to be much better.

If your going to covert to LPG I wouldn't even bother with the old vapour systems. Do a search for liquid LPG Injection and you will see why liqud is so much better.

Here is a source I found (http://www.rasoenterprises.com/cars/Propane-Kits-PersonalCars.htm) look at the "Fleet" tab also more kits , they have a list of several kits , roger on the injection .
Saw that some making 1000hp on LPG .
Looks like this one uses O2 sensors : http://www.technocarb.com/images/stories/ESIP-Eng-Brochure.pdf
Read the last part about tuning : http://www.rasoenterprises.com/cars/Propane-SVIS-Impala.htm , more tuning stuff : http://www.msextra.com/ms2extra/MS2-Extra_Conversion.htm#tableswitch
Using post as repositories . :)
I bet you already know all this , so it is just reference for future searches .

[Wrath23]

They are vapour injection kits. If you want to make big HP you need liquid injection. Is very difficult to flow enough LPG vapour through the injectors to support big hp and still be able to control the idle. Not to mension the major cooling effect of liquid injection. Vapour system typically make less power then gasoline while liquid produces more.

[Chevy366]

They are vapour injection kits. If you want to make big HP you need liquid injection. Is very difficult to flow enough LPG vapour through the injectors to support big hp and still be able to control the idle. Not to mension the major cooling effect of liquid injection. Vapour system typically make less power then gasoline while liquid produces more.
Adding to the repository . :)
http://www.australianlpgwarehouse.com.au/Products/Systems/JTG-Liquid-Injection.aspx
http://www.icomitalia.it/lang1/index.html
I am on Puppy Linux running from a CD , so when I stop it is gone so I am just putting what I find here . :secret:

[Wrath23]

Ok getting back to the flex fuel issue. What I'm thinking of doing ATM is to change the FF setting in the PCM from calculated to sensor, then I will use a simple pulse generator circuit to activate the FF tables and will also take a readng from the LPG temp sensor and vary the pulse width to give the PCM feedback on the LPG temp.

Can anyone see any problems with this?
Is it possible to use a sensor on a calculated system? Is there an input for the sensor?

[Chevy366]

Ok getting back to the flex fuel issue. What I'm thinking of doing ATM is to change the FF setting in the PCM from calculated to sensor, then I will use a simple pulse generator circuit to activate the FF tables and will also take a readng from the LPG temp sensor and vary the pulse width to give the PCM feedback on the LPG temp.

Can anyone see any problems with this?
Is it possible to use a sensor on a calculated system? Is there an input for the sensor?
Are you going to run multiple fuels , LP plus Petrol ? If using single fuel then I would just tune for that fuel .
Isn't this a stand alone fueling , meaning LPG fuel only to start and run ?
Don't you tune the LPG system to mimic regular fueling ?
Just curious as to why the FF fueling scenario , does LPG fluctuate that much . LPG 10 to LPG 85 ?

[gmh308]

Ok getting back to the flex fuel issue. What I'm thinking of doing ATM is to change the FF setting in the PCM from calculated to sensor, then I will use a simple pulse generator circuit to activate the FF tables and will also take a readng from the LPG temp sensor and vary the pulse width to give the PCM feedback on the LPG temp.

Can anyone see any problems with this?
Is it possible to use a sensor on a calculated system? Is there an input for the sensor?

Now you got it! :) Just gotta find the 1, 2 or 3 pins that support the hard sensor. :secret:

[Wrath23]

Yes the system will run on the standard fuel system perfectly fine. They are disigned so you can just install the system and test drive without tuning. However Lpg has a higher octane the petrol (104 to 110) and stoichametric for LPG is 15.5 so I offer a seperate tune for my customers that is optimized for LPG that way they get more power and better economy figures than petrol. I like to use 2 seperate tunes so I don't have to compromise between the different fuels

[gmh308]

Yes the system will run on the standard fuel system perfectly fine. They are disigned so you can just install the system and test drive without tuning. However Lpg has a higher octane the petrol (104 to 110) and stoichametric for LPG is 15.5 so I offer a seperate tune for my customers that is........

optimized for LPG that way they get more power and better economy figures than petrol.

I like to use 2 seperate tunes so I don't have to compromise between the different fuels

That's impressive. My experiences with LPG, and I am talking older systems, was the opposite. Sounds like the technology has come a long way. No wonder LPG is seen on turbo installs with octane #'s towards the 110 space. :)

[Wrath23]

Yeah the new sytems are far better then the older systems and by 'old' I mean even those developed a couple of years ago. The liquid systems really perform well typically producing 10% more power then fuel without tuning, with a little tuning I have seen an 18% increase on a turbo charged vehicle. The beauty of it is economy rate stays the same and the LPG cost 1/3 the price. It's a good cheap race fuel!

[gmh308]

Yeah the new sytems are far better then the older systems and by 'old' I mean even those developed a couple of years ago. The liquid systems really perform well typically producing 10% more power then fuel without tuning, with a little tuning I have seen an 18% increase on a turbo charged vehicle. The beauty of it is economy rate stays the same and the LPG cost 1/3 the price. It's a good cheap race fuel!

mmm.....thinking, thinking, thinking.....what is a kit for an LS engine worth?

[Wrath23]

Kits for Holden commodores are around 6k installed. In Australia the government will pay 2k for the install, with the fuel saving it will pay for itself after 2 -3 years depending how much driving you do. I save about $60 a week

[Wrath23]

Does anyone know if all E38 PCMs have the same pinouts?

I would imagine the pinouts would be the same just different harness.
I'm trying to find the fuel composition input to the PCM