csimoes Posted September 13, 2013 Share Posted September 13, 2013 after reading about this subject there's something i'm not understanding (just one ahahahahhah yeah right) my current setup for the v8 is LUCAS ECU with sequential LPG from BRC (with its own LPG ecu) if i'm not wrong the LPG ECU tricks the LUCAS ECU and turnes of the fuel injectors and uses the LPG injectors, but uses the fuel maps from the LUCAS ECU. am i right? makes any sense? now i'm going MS and EDIS and i'm planning on use the switching advantage from this setup (petrol vs LPG) and this is my problem, because i keep reading this... "For simplicity I'd keep the LPG system as a standalone system and use MS in dual map mode. If you hook the map switch input up to the LPG solenoid circuit whenever the LPG system is activated/deactivated the MS automatically changes maps.You can configure the MS to switch both fuel and ignition with a different ignition curve for each fuel and simply zero the fuel map for LPG. The map switching can be phased in over a couple of seconds, giving a really smooth change from one fuel to the other." if i do this (being that the MS replaces the LUCAS ECU) won't i be without any injection? the LPG ECU doesn't have any fuel maps right? cheers Quote Link to comment Share on other sites More sharing options...
Quagmire Posted September 13, 2013 Share Posted September 13, 2013 Setting the fuel map to zero is what you would do if you were using non injected (mixer ring) lpg. With injected lpg you have two ways to do this as you have the lpg ecu already. 1- forget map switching and wire the lpg ecu in exactly as it was with the Lucas setup I.e. intercepting and adjusting the pulse widths on gas . 2- forget the lpg ecu and use ms to switch maps and fire injectors. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 13, 2013 Share Posted September 13, 2013 2 is nicer as you can tune it properly for LPG and run closed-loop rather than just copying the petrol map plus or minus some fudge factor. Quote Link to comment Share on other sites More sharing options...
elbekko Posted September 13, 2013 Share Posted September 13, 2013 For sequential LPG you have to have a fuel map. The way I'd do it is: - Set the LPG ECU map to 90 or 100 all around, whatever means direct translation. - Copy the MS petrol map to a separate map, and tune it while running on LPG. You can also fiddle with MS to drive the LPG injectors, but then you don't have the gas pressure correction etc. Quote Link to comment Share on other sites More sharing options...
csimoes Posted September 13, 2013 Author Share Posted September 13, 2013 Ok. Keeping the lpg ecu, I payed for it so I'm using it The way to go is to have the two fuel maps and respective ignition tables And spend the time to fine tune the fuel maps for which of the fuels Did I get it? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 13, 2013 Share Posted September 13, 2013 Same fuel map will be fine for both LPG and petrol, as the LPG ECU modifies the injector pulse times to suit the LPG injectors characteristics, so it needs the SAME nicely-tuned petrol map to work from. You do of course need to tweak the LPG spark table to suit, this gives a lot of good benefits Quote Link to comment Share on other sites More sharing options...
csimoes Posted September 13, 2013 Author Share Posted September 13, 2013 Great! Thanks for all your answers guys To fine tune, better to do it on petrol or LPG? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 13, 2013 Share Posted September 13, 2013 Which do you expect to use most? I'd tune for that and let the other one alone. Quote Link to comment Share on other sites More sharing options...
elbekko Posted September 13, 2013 Share Posted September 13, 2013 Same fuel map will be fine for both LPG and petrol, as the LPG ECU modifies the injector pulse times to suit the LPG injectors characteristics, so it needs the SAME nicely-tuned petrol map to work from.You do of course need to tweak the LPG spark table to suit, this gives a lot of good benefits No it doesn't, getting the LPG ECU's map right is a LOT harder than having MS doing it. You have two maps, both fuel and ignition, use them. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 13, 2013 Share Posted September 13, 2013 Huh? Sorry but that goes against everything I know about LPG injection ECUs. Care to elaborate? Quote Link to comment Share on other sites More sharing options...
csimoes Posted September 13, 2013 Author Share Posted September 13, 2013 I basically use petrol to start and warm up until a certain temp and then switches automatically to LPG So I should fine tune it on LPG. I already opened another topic about stroich for petrol/LPG, from that information, tunerstudio will be ok to fine tune on LPG, right? Quote Link to comment Share on other sites More sharing options...
elbekko Posted September 13, 2013 Share Posted September 13, 2013 Huh? Sorry but that goes against everything I know about LPG injection ECUs. Care to elaborate? An LPG ECU takes the injector pulse from the petrol injector, and then translates it to an injector pulse for the LPG injector. The map is basically a percentage of the petrol injector time, plotted in rpm vs opening time. If you just keep this map constant, you can let MS do the finetuning, and just have the LPG ECU do the driving of the LPG injectors, and add a few corrections based on gas pressure vs manifold pressure etc. If you use a narrow-band lambda, you don't need to change anything to tune for LPG, lambda = lambda. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 13, 2013 Share Posted September 13, 2013 I can see how that could work, yes, so once you have done the auto-tune routine for the LPG, you then tune it finely using MS, is that what you are suggesting? I agree a narrow band is fine for tuning LPG or petrol. Quote Link to comment Share on other sites More sharing options...
csimoes Posted September 13, 2013 Author Share Posted September 13, 2013 Great info guys Keep it coming Thanks Quote Link to comment Share on other sites More sharing options...
elbekko Posted September 14, 2013 Share Posted September 14, 2013 I can see how that could work, yes, so once you have done the auto-tune routine for the LPG, you then tune it finely using MS, is that what you are suggesting?I agree a narrow band is fine for tuning LPG or petrol. I wouldn't even bother doing the LPG auto-tune, just having the flat map will make life MUCH easier for MS. Incidentally, this is how I have my current LPG set up (apart from a little leaning at the top of the map), and the Bosch ECU seems to handle it fairly well. Quote Link to comment Share on other sites More sharing options...
bobtail84 Posted November 6, 2013 Share Posted November 6, 2013 Just a small question....... The LPG injectors will be low z and the hot wire are high z. Have you worked out how to run both types on 1 MS ecu? I have tried twice and fried 1 cpu and lots of smaller diodes on the injector side. Just asking. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 6, 2013 Share Posted November 6, 2013 I'd just add resistors to the low-Z ones (as they did with Flapper), from memory you want about 5-6 Ohms per injector, the aluminium bodied power resistors are the thing. Quote Link to comment Share on other sites More sharing options...
bobtail84 Posted November 7, 2013 Share Posted November 7, 2013 Yup tried that and tried using a flapper resistor pack but it makes tuning the low z injectors a proper pain. It ran perfectly when I changed the settings in engine constants but you then have no petrol option. If you use the original LPG ECU to run the injectors you can use the MS ECU for the spark and all other aspects of lovely V8 runningness. You only need a 3 way switch, 2 magic switching boxes and some wire of different colours. Possibly some beer, a number of connectors, reading glasses if needed, time and more beer. You will need to have your MS ECU configured for switching tables and whilst Fridge has the top off ask him to do the fan/water inj out as well. Its just a small case of wiring.. One way is when you switch to LPG you can spur off of the live for the 12v to pin6 JP1 and will switch to VE table 3 and spark table 2. If you put '0's in VE table 3 the rest of the engine management will be controlled as normal by the MS ECU. You may have to have 2 Lambda sensors, one for each fuel if the LPG ECU needs one. I have done this and also I have a 'cooker ring' on my RRC daily driver with no problems. HTH Quote Link to comment Share on other sites More sharing options...
csimoes Posted November 8, 2013 Author Share Posted November 8, 2013 maybe a stupid question but.... how do i confirm that MS swichted to the second spark table? yesterday while connect the gauge would still show spark advance for petrol, but if i went and look at the tables they would show the dot going up and down, both of them......... Quote Link to comment Share on other sites More sharing options...
bobtail84 Posted November 9, 2013 Share Posted November 9, 2013 maybe a stupid question but.... how do i confirm that MS swichted to the second spark table? yesterday while connect the gauge would still show spark advance for petrol, but if i went and look at the tables they would show the dot going up and down, both of them......... No its not a stupid question it just how the TS works. If you look at the attached doobree you will see from the left on the fuel table selection that " switch to table 3" has been selected, and spark table selection "spark table 2" is selected. Also on the drop down for spark table 2 option is not greyed out. Another way is if you put '0's in the spark 2 or VE3 maps and when you have it switched to what you think is the other maps then is should not run. If it runs then it's not switching. Quote Link to comment Share on other sites More sharing options...
csimoes Posted November 10, 2013 Author Share Posted November 10, 2013 Ok now i see what i did wrong... I only switched spark table, didn't do the same to fuel I thought i could switch only spark And leave fuel the same Thanks Quote Link to comment Share on other sites More sharing options...
csimoes Posted November 10, 2013 Author Share Posted November 10, 2013 well tried that solution and nothing happened confirmed that the LPG comes on, the signal on spare 1 gets to 12v, before that is on 1.2v what am i doing wrong? Quote Link to comment Share on other sites More sharing options...
csimoes Posted November 11, 2013 Author Share Posted November 11, 2013 any thoughts? any one?? Quote Link to comment Share on other sites More sharing options...
Quagmire Posted November 11, 2013 Share Posted November 11, 2013 You sure your MS is not setup to switch when grounded? What happens if you earth the relevant pin, does it changeover then? Quote Link to comment Share on other sites More sharing options...
csimoes Posted November 12, 2013 Author Share Posted November 12, 2013 i was told by the builder that should put 12v on spare1 but i'll try earthing it, it won't do any damage trying it.... Quote Link to comment Share on other sites More sharing options...
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