Hello all,
I'm rebuilding an old Dodge D200 with a 5.2L V8. Because of the fuel prices here, i would like to drive on LPG. For this i have bought vapor injectors, the reducer, sensors, etc. Because i would like to go fully sequential on the MS3 i also ordered the MS3x (just started to solder it yesterday).
Now for the tricky part (to me). I want to make the LPG switch process automatically on cold start. I believe i can do this if i ad some components. I will be making my own PCB for some more components and an other connector, so placing them inside is no problem.
Here is the question. When i would use the MS3 and set it up as following:
- VVT output, to high if: 70 degree Celsius and LPG pressure +0,5 bar
- Table in, for the LPG table and settings
and then make the following circuit
K1 will be the Fuel pump relay, and giving +12V to the fuel injectors
K2 will be the relay that opens all LPG valves etc. , and giving +12V to the LPG injector driver (AEM injector driver)
S1 will be the selector switch on the dashboard
If i'm right, on cold startup and the switch in LPG setting, the engine should start on fuel. This because VVT output is nog yet high (coolant <70 degree Celsius). Fuel pump should run, because Q4 will not conduct, making Q2 conducting. When temperature reaches 70 degree, Q2 will stop conducting (fuel pump stops), and Q1 will pull the table switch input low to switch to the LPG mapping.
The other way round, when the switch is on Fuel, Q1 and K2 won't be powered and therefore only the fuel pump (powered by the switch) will be active.
Is this correct or is my diagram way off? And maybe someone can help with the resistor value's and transistor type's? I'm not an expert at all on this, so it would be great to get some help.
Thanks!
Best regards,
Bart
LPG / Fuel switch
Moderators: jsmcortina, muythaibxr
Re: LPG / Fuel switch
Dear Bart,
I'm not sure I'd bother with any of this.
Firstly, MS3 is quite capable of starting and running the engine on LPG from cold. This is how I run my car and it starts better on LPG than it ever does on petrol, probably because the fuel is always perfectly atomised.
Secondly, all aftermarket LPG systems keep the petrol fuel pump running on account of not toasting the petrol injectors, gumming them up with varnish deposits if they are unused and evaporating what fuel is left sitting idle in the petrol fuel rail.
kind regards
Marek
I'm not sure I'd bother with any of this.
Firstly, MS3 is quite capable of starting and running the engine on LPG from cold. This is how I run my car and it starts better on LPG than it ever does on petrol, probably because the fuel is always perfectly atomised.
Secondly, all aftermarket LPG systems keep the petrol fuel pump running on account of not toasting the petrol injectors, gumming them up with varnish deposits if they are unused and evaporating what fuel is left sitting idle in the petrol fuel rail.
kind regards
Marek
Re: LPG / Fuel switch
Hello Marek,
Thanks for your reply! I will leave the fuel pump running then. I can remember indeed that that was the case on an old LPG car i had too. And based on the things you write i can imagine that it will be better.
About the starting on LPG; the old car i used to have always started on petrol. I can also remember that it had to do with backfire, since air speed is relatively low at starting RPM. I can also imagine that the reducer will freeze when it is cold outside? The cooling system is not warming up quickly on these heavy engines.
When i will have the extra PCB made, i guess I'd better make the extra possibility in it? When it will not be needed it is easier to just ignore the extra circuit. I have got plenty of room left on the PCB so that shouldn't be the problem. I adjusted the circuit:
Can someone tell me if this would work? I'm not really an electronics engineer ;)
Best regards to all!
Thanks for your reply! I will leave the fuel pump running then. I can remember indeed that that was the case on an old LPG car i had too. And based on the things you write i can imagine that it will be better.
About the starting on LPG; the old car i used to have always started on petrol. I can also remember that it had to do with backfire, since air speed is relatively low at starting RPM. I can also imagine that the reducer will freeze when it is cold outside? The cooling system is not warming up quickly on these heavy engines.
When i will have the extra PCB made, i guess I'd better make the extra possibility in it? When it will not be needed it is easier to just ignore the extra circuit. I have got plenty of room left on the PCB so that shouldn't be the problem. I adjusted the circuit:
Can someone tell me if this would work? I'm not really an electronics engineer ;)
Best regards to all!
Re: LPG / Fuel switch
By the way, for all of you interested, the picture of how the inlet manifold will look:
I have drawn it in 3D CAD and also flow tested it. Main point was not to get the most power, but to have a manifold that has enough runner length for LPG injection, and have an equal amount of air to each cylinder (as much as possible). Couple of small details will change, but this is about it.
I have drawn it in 3D CAD and also flow tested it. Main point was not to get the most power, but to have a manifold that has enough runner length for LPG injection, and have an equal amount of air to each cylinder (as much as possible). Couple of small details will change, but this is about it.
Re: LPG / Fuel switch
When looking at the datalogs, the smoothness of the idle does look to improve at about 50'c, although this isn't perceptible in normal running. I am guessing that at this point, all of the heat needed to vapourise the LPG is provided by the circulating coolant and not coming from reducing the ambient temperature of the surrounding environment.
I have 19 litres of coolant so it is difficult if not impossible to freeze the reducers unless the coolant flow is very restricted. When this has happened with poor coolant flow, it didn't stop the engine from running as the underhood temperature was sufficiently high to always melt the ice.
kind regards
Marek
I have 19 litres of coolant so it is difficult if not impossible to freeze the reducers unless the coolant flow is very restricted. When this has happened with poor coolant flow, it didn't stop the engine from running as the underhood temperature was sufficiently high to always melt the ice.
kind regards
Marek
Re: LPG / Fuel switch
That's a clear answer. However i still would like to incorporate it in the PCB. Not because i believe it is really necessary, but just because it is possible. I just would like to make 1 PCB that contains everything possibly necessary, so i won't have to change anything. There will also be some small circuits on there for JS4 & JS5 ADC, VW COP driver IC's and a separate 5V supply for the COP drivers.
Surely i will start the first time without this circuit, but afterwards i could look if it makes a difference. Do you know if the circuit itself would work? My believe is that it should, but I bet there are more experienced people out there
Surely i will start the first time without this circuit, but afterwards i could look if it makes a difference. Do you know if the circuit itself would work? My believe is that it should, but I bet there are more experienced people out there
Re: LPG / Fuel switch
Connect 85 to a 12v source which is ignition switched, perhaps with an inertia switch in series if so desired.
Connect 86 to MS fuel pump sink
Connect 30 to 12v
Connect your petrol fuel pump to 87 via a suitable fuse
For the LPG, use a second relay:-
Conect 85 to the first relay's 85
Connect 86 to the MS tableswitch pin
Connect 30 to the first relay's 87 via a suitable fuse
Connect 87 to the lpg reducers and tank solenoids (and earth the other side of the solenoids). Connect up a suitably resistored green LED to 87 also and earth the other side of that.
Connect 87a to a suitably resistored red LED and earth the other side of that.
When running petrol, the red LED will light.
When MS's tableswitch is earthed either using a manual switch to earth or some fancy electronics, the green LED will light instead if and when the MS's fuel pump output allows it. Fused 12v goes to the lpg solenoids. The petrol fuel pump always keeps running subject to MS and the inertia switch.
The LEDs show you which fuel is being used and whether or not the fuses have blown.
This way, the MS is only ever grounding a small current signal to a relay coil.
If you are really feeling clever, hook up a single dual colour red/green LED
and make table switch subject to a minimum temperature at the reducer and a minimum pressure output at the reducer. That's basically how I have mine, with the conditional parts making the LED flash alternately red and green so I know it wants to changeover back to petrol but hasn't yet.
kind regards
Marek
Connect 86 to MS fuel pump sink
Connect 30 to 12v
Connect your petrol fuel pump to 87 via a suitable fuse
For the LPG, use a second relay:-
Conect 85 to the first relay's 85
Connect 86 to the MS tableswitch pin
Connect 30 to the first relay's 87 via a suitable fuse
Connect 87 to the lpg reducers and tank solenoids (and earth the other side of the solenoids). Connect up a suitably resistored green LED to 87 also and earth the other side of that.
Connect 87a to a suitably resistored red LED and earth the other side of that.
When running petrol, the red LED will light.
When MS's tableswitch is earthed either using a manual switch to earth or some fancy electronics, the green LED will light instead if and when the MS's fuel pump output allows it. Fused 12v goes to the lpg solenoids. The petrol fuel pump always keeps running subject to MS and the inertia switch.
The LEDs show you which fuel is being used and whether or not the fuses have blown.
This way, the MS is only ever grounding a small current signal to a relay coil.
If you are really feeling clever, hook up a single dual colour red/green LED
and make table switch subject to a minimum temperature at the reducer and a minimum pressure output at the reducer. That's basically how I have mine, with the conditional parts making the LED flash alternately red and green so I know it wants to changeover back to petrol but hasn't yet.
kind regards
Marek
Re: LPG / Fuel switch
Hey Marek,
I have drawn it up, and it will be kind of the same of what i have, only difference is that i use a MS pin (VVT) to switch at temperature. I like the Red/Green led idea though, gotta find a way to incorporate that in the dash! Nice to know the status without the laptop.
Thanks again!
Best regards,
Bart
I have drawn it up, and it will be kind of the same of what i have, only difference is that i use a MS pin (VVT) to switch at temperature. I like the Red/Green led idea though, gotta find a way to incorporate that in the dash! Nice to know the status without the laptop.
Thanks again!
Best regards,
Bart
Re: LPG / Fuel switch
I'm not sure our setups are are quite the same at all.
If you look at the harware manual, the MS processor pins generally can provide voltage to power a transistor base so as to switch a larger load between the tranistor's collector and emitter OR the MS processor pins can sink only a limited amount of current to earth.
Your previous diagrams appear to have the tableswitch pin and vvt pin connecting to eachother as output to input for no good reason if switch s1 is closed.
You have 12v on the lpg relay solely dependent on switch s1 regardless of what vvt or tableswitch do - these are on the "other side" of the transistor cicrcuit and can't "see" the lpg relay, i.e. the collector isn't supposed to try and control the base - it's usually the other way around unless you want to somehow reverse bias the transistor in the same way as a zener conducts and if you were to do that, then the tableswitch pin would have to attempt to power the relay when s1 were open circuit.
kind regards
Marek
If you look at the harware manual, the MS processor pins generally can provide voltage to power a transistor base so as to switch a larger load between the tranistor's collector and emitter OR the MS processor pins can sink only a limited amount of current to earth.
Your previous diagrams appear to have the tableswitch pin and vvt pin connecting to eachother as output to input for no good reason if switch s1 is closed.
You have 12v on the lpg relay solely dependent on switch s1 regardless of what vvt or tableswitch do - these are on the "other side" of the transistor cicrcuit and can't "see" the lpg relay, i.e. the collector isn't supposed to try and control the base - it's usually the other way around unless you want to somehow reverse bias the transistor in the same way as a zener conducts and if you were to do that, then the tableswitch pin would have to attempt to power the relay when s1 were open circuit.
kind regards
Marek
Re: LPG / Fuel switch
Hey Marek,
As i said, I'm not an true expert on these matters, but as far as i know the transistor can't reverse current from base to collector?
The basic idea of it is especially that the LPG system is powered up before MS3X_VVT is going low (when engine reaches setup temp and lpg pressure).
The VVT can switch up to 3A (according to the manual?) seems to me it should be enough since the 10k resistor will have about 0.002A and the sink from the Tableswitch pin should be about 0.003A?
Maybe the diode D8 shouldn't be there, that shouldn't have any function?
Don't get me wrong, it's really not because i think i know better, but I want to make sure i understand why it shouldn't work like that. That will prevent me making the same mistake twice
I believe learning is better than just acting
Best regards,Bart
As i said, I'm not an true expert on these matters, but as far as i know the transistor can't reverse current from base to collector?
The basic idea of it is especially that the LPG system is powered up before MS3X_VVT is going low (when engine reaches setup temp and lpg pressure).
The VVT can switch up to 3A (according to the manual?) seems to me it should be enough since the 10k resistor will have about 0.002A and the sink from the Tableswitch pin should be about 0.003A?
Maybe the diode D8 shouldn't be there, that shouldn't have any function?
Don't get me wrong, it's really not because i think i know better, but I want to make sure i understand why it shouldn't work like that. That will prevent me making the same mistake twice
I believe learning is better than just acting
Best regards,Bart
Re: LPG / Fuel switch
The tableswitch pin works like this:- you have earth on one side of a switch and you have tableswitch connected to the other side of the switch. You close the switch and the car now runs on VE3 instead of VE1.
Tableswitch is not an earth provider or a 12v provider - it simply asks - am I being earthed?
If it is to be part of a transistor circuit, then typically it is held high using a resistor (called a "pullup" resistor) between positive and collector/tableswitch and when the transistor is made to conduct, tableswitch gets dragged low (because the voltage drops across the two ends of the resistor now that a path through the transistor to earth has been established - prior to this the transistor wasn't conducting and both sides of the resistor were simply sitting at "positive", that being typically 12 or 5v.
This means you should use your s1 switch not for adding the 12v but for tableswitching earth.
Then make the VVT output only go high using the rules "tableswitch=0" AND "CLT>70" and use it for the 12v source and are done.
kind regards
Marek
Tableswitch is not an earth provider or a 12v provider - it simply asks - am I being earthed?
If it is to be part of a transistor circuit, then typically it is held high using a resistor (called a "pullup" resistor) between positive and collector/tableswitch and when the transistor is made to conduct, tableswitch gets dragged low (because the voltage drops across the two ends of the resistor now that a path through the transistor to earth has been established - prior to this the transistor wasn't conducting and both sides of the resistor were simply sitting at "positive", that being typically 12 or 5v.
This means you should use your s1 switch not for adding the 12v but for tableswitching earth.
Then make the VVT output only go high using the rules "tableswitch=0" AND "CLT>70" and use it for the 12v source and are done.
kind regards
Marek
Re: LPG / Fuel switch
Hey Marek,
Sorry for all these questions, but with the circuit i have drawn, i don't request the table switch pin anything? It will only be grounded though the VVT when the transistor conducts (so the VE3 map will be selected). This happens (to my knowledge) when current flows through the switch, through R11, through the base of the transistor, to the emitter and then to VVT)
At least, that's what I've always been told? 
The relay will be powered as soon as i flip the switch to LPG, making it possible to prepare the pressure in the system. Then when temperature is high enough, VVT will become low, making the transistor conduct, and making the table go to VE3? At this same moment the LPG injectors should be powered and the petrol injectors should stop.
When i would use the switch to ground the table switch, mapping will go to VE3. But since there is no pressure on the LPG system, the fuel injectors are still used. This would take untill the engine reaches >70 degree.
Again, I'm really sorry for these questions, but i just don't get it. And i do want to make sure I build it right and make it a succes story ;)
Greetings
Sorry for all these questions, but with the circuit i have drawn, i don't request the table switch pin anything? It will only be grounded though the VVT when the transistor conducts (so the VE3 map will be selected). This happens (to my knowledge) when current flows through the switch, through R11, through the base of the transistor, to the emitter and then to VVT)
At least, that's what I've always been told?
The relay will be powered as soon as i flip the switch to LPG, making it possible to prepare the pressure in the system. Then when temperature is high enough, VVT will become low, making the transistor conduct, and making the table go to VE3? At this same moment the LPG injectors should be powered and the petrol injectors should stop.
When i would use the switch to ground the table switch, mapping will go to VE3. But since there is no pressure on the LPG system, the fuel injectors are still used. This would take untill the engine reaches >70 degree.
Again, I'm really sorry for these questions, but i just don't get it. And i do want to make sure I build it right and make it a succes story ;)
Greetings
Re: LPG / Fuel switch
Sadly, your tableswitch pin has a blocking diode in front of it and it isn't connected to anything else, so it'll always be floating and doing nothing.
It expects to be treated as an input:- if it is fed 12v (and the blocking diode stops this) or left unconnected, then it'll be high and untableswitched. If it is connected to earth, then it'll be low and the maps will switch.
The VVT output appears to be a sink at the emiter end of an NPN transistor and not a provider of 12v to anywhere and certainly not to the tableswitch pin, as that is blocked from receiving anything.
I suggest you get some stripboard and test this circuit to see what it does before you go any further.
kind regards
Marek
It expects to be treated as an input:- if it is fed 12v (and the blocking diode stops this) or left unconnected, then it'll be high and untableswitched. If it is connected to earth, then it'll be low and the maps will switch.
The VVT output appears to be a sink at the emiter end of an NPN transistor and not a provider of 12v to anywhere and certainly not to the tableswitch pin, as that is blocked from receiving anything.
I suggest you get some stripboard and test this circuit to see what it does before you go any further.
kind regards
Marek
Re: LPG / Fuel switch
Hey Marek,
A small question as to you reply with:
Can you tell me how to do that?
EDIT: it would be even easier when VE3 would be selected not only by the tableswitch, but also by the coolant temp. but as far as i can find, there is no such option?
A small question as to you reply with:
I can't find that option. It would save me the transistor in that case, solving a lot. But somehow i don't see it in the Advanced engine - Programmable On/Off Outputs .Then make the VVT output only go high using the rules "tableswitch=0" AND "CLT>70" and use it for the 12v source and are done.
Can you tell me how to do that?
EDIT: it would be even easier when VE3 would be selected not only by the tableswitch, but also by the coolant temp. but as far as i can find, there is no such option?
Re: LPG / Fuel switch
Use the Active Conditions of the Programmable On/Off Outputs
"Status1" can be used to monitor whether you have managed to earth your tableswitch (status1 AND 128 or whatever the right number is - go look it up)
"coolant" can be used to act the level of the CLT temperature
Use the "And" to link them.
VVT will then be set high or low dependent on how you link the conditions.
kind regards
Marek
"Status1" can be used to monitor whether you have managed to earth your tableswitch (status1 AND 128 or whatever the right number is - go look it up)
"coolant" can be used to act the level of the CLT temperature
Use the "And" to link them.
VVT will then be set high or low dependent on how you link the conditions.
kind regards
Marek
Re: LPG / Fuel switch
Hey Marek,
I found this:
That means that for VVT i setup under Active Conditions:
- coolant >70 hysteresis 5
and
-status1 AND 32
If I'm correct? Didn't know that was possible, but that's fantastic!
THANKS i learned again!!
Greetings,
Bart
I found this:
Code: Select all
indicator = { status1 & 32}, "VE1/2", "VE3/4", white, black, green, black- coolant >70 hysteresis 5
and
-status1 AND 32
If I'm correct? Didn't know that was possible, but that's fantastic!
THANKS i learned again!!
Greetings,
Bart
Re: LPG / Fuel switch
Now that i have that working, i have one more question. On the extra PCB I'm drawing up, i will have 4 pieces of the TC4427. This to drive two 06A 905 097 coils (VW with 4 channels). I have read on the net that with the MS3x you should use those? The circuit is simple with the 15R resistor. On the "proto 5V / S12C" side i plan to use 5V, but i can't really tell for sure how much current this will draw. Will I need an extra 7805 circuit, or can i leave this out and use the MS3 5V? I use almost all of the analogue inputs (including JS4 & JS5 in the near future). I know the 5V from the board should do 500mA but i don't know if this total will ask to much of this power supply?
Had the soldered board on 12V supply yesterday, and up to now, everything goes great!
The extra piece of aluminum is for the fixing to the custom casing (also aluminum so it is cooling a little bit more as well as a good fixing point).
Had the soldered board on 12V supply yesterday, and up to now, everything goes great!
The extra piece of aluminum is for the fixing to the custom casing (also aluminum so it is cooling a little bit more as well as a good fixing point).
Re: LPG / Fuel switch
Can anyone verify that this is correct to switch when the table switch is active:
Thanks!and
-status1 AND 32
Re: LPG / Fuel switch
Nobody knows? 
Anyway, my ordered PCB's have came in. Connector adapter, coil drivers and some resistors and capacitors for extra analogue inputs. Hopefully this weekend i can solder it together.
Anyway, my ordered PCB's have came in. Connector adapter, coil drivers and some resistors and capacitors for extra analogue inputs. Hopefully this weekend i can solder it together.