astra 1.4 8valve lpg turbo.
Turbo Mini Forums

well after a bit of research i have found out this stuff...


my ecu..

http://www.diyautotune.com/catalog/megasqu...case-p-119.html

seems to be able to do pk and hold for 3ohm injectors , i was chatting with joe about this ,and was going to use a set of 4 resistors ,but cannot remember if that was when i was going to use a ms1 not a stonko ms2. so not sure if i should still use resistors or try to set ms to pk and hold?



injector specs....

2 POWER OF COIL 48 W – 144 W
3 PILOTING TYPE PEAK and HOLD
4 TIME FOR PEAK CURRENT 4,5 ms
6 RESISTANCE 3 Ohm +-4% - 1 Ohm +-4%
9 MAX WORKING PRESSURE 0,45 Mpa At 12V D.C.
11 NUMBER VALVE SEAT AVAILABLE 4,3,2 and single
12 OPENING TIME 3,3 ms
13 CLOSING TIME 2,2 ms
14 WORKING TIME 100%
15 MAX AMBIENT WORKING TEMPERATURE -20
16 MEDIUM TEMPERATURE -3018 INLET/OUTLET Connection for rubber hose D 10 mm IN and D 5 mm OUT
22 VALVE SEAT DIAMETER 4.0 mm

seem a bit clunky on the time for opening/closing and so on ,but apparenty lpg injectors are thus.


and heres a few pics of bits and pieces ...


















not really sure if the one temp sensor on the vap is enough for good economy ,no pressure or gas temp input ,but i suppose the pressure and gas temp are pretty relative to the water temp in the vap ? ah ,well time will tell. :) thinking i will use the temp on the vapouriser for my water temp sensor input ,and see how it works .

good thing is i already have the engine on megajolt ,so a simple swap to squirt on the ignition front .

Edited by robert on 30th Oct, 2012.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

yep can use the resistors with any of the MS's

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

its the easiest I think,

jean would be best to advise as to which is better, hopefully he'll see this.

viable..?

http://uk.rs-online.com/web/p/panel-mount-...istors/0157550/

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Ideal, one per injector.

even at 100% duty cycle you'll be disapating 10watts, so you easily have a 50% margin.

theres a suggestion on the lpg forum joe ,that a low imp injector on resistors may not be able to open against 2 bAR GAS , so this bit in the manual looks encouraging for pk and hold ...

PWM Current Limit (%) = 75% (30% if you have the flyback board installed). NOTE: the V3.0 pcb should already have the relavent flyback components fitted, the flyback board is only for the V2.2 or V1.0 boards.


since i have the v3 pcb ,watjafink ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

found this bit from jean on the ms2 extra forum ,seems pertinent..




PWM is no longer available when using 4 injector channels. The 2 pins used for PWM are now used for the 2 extra channels (that's also why you don't lose any I/O when doing the conversion). So you have 2 choices: use inline resistors or use external peak&hold drivers. The other option is to go back to using 2 injector channels with PWM.

I know of someone using resistors on LPG injectors with good results. But he was using a low resistor value such as 2 or 3 Ohms. And the peak&hold drivers, while the best method in theory, can be problematic with those injectors since they don't have the same characteristics as the liquid fuel injectors the drivers are designed for.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Unless you have had your MS2 built for sequential, it will have the standard 2 injector drivers.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

one reason I sugested the resistors was that the low imp injectors can introduce noise due to the higher current, this can manifest itself as sync problems on the crank trigger, or causing the accell enrichment to kick in etc.

as your on edis I think the crank trigger signal is unlikly to get disturbed, so its worth a go as peak and hold, you can always stick resistors in later.

we ned Rods input, he's mr peak and hold isnt he?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Rod's currently on the black stuff :)

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

???

LOL oh yeah,

I remember him posting about a trip to ireland now.

http://fuelsforum.rasoenterprises.com/view...t=1062&start=15


intersting bit in here about using resistors..

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

makes the resistors look promising,

yes , it seems that there are two problems ... problem 1 is , using pk and hold function ,either with ms or new pk and hold board , the lpg inj have a very different characteristic behaviour ,maybe much heavier moving internals etc ,so they do'nt really match the pk and hold currect designed for petrol inj .
problem 2 is , if using resistors ,they can reduce the currect beow whats needed .notice the chap in the link used much less ohms than i was thinking of , so maybe thats the key . to realise the lpg inj need different rules ,and one can use a smaller ohm resistor without burning out the ms ?

he used 1ohm 25w resistors , so a total of 4 ohms with the 3 ohm inj . which would give 3.9 amps 49 watts with 14v battery ,per injector !
so looking at the manual , it seems that 2 amps is the max i can have ,so that would mean a 4 ohm resistor?

something else to notice is ,looking at this ...




you need a long enough pulse at first to bang the inj open , now , looking at our inj specs, a petrol inj may need 1ms to open ,but a lpg inj needs 3.3ms to open ,and 2.2 ms to close ,maybe the pk anf hold spike doesnt go on for long enough ?

i am probably drivelling here !

Edited by robert on 1st Nov, 2012.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

ah , you can set the pk spikes duration in the setup in tuner s ...,but does setting it to 3.3ms overheat things ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

you should be ok, the ms injector outputs are meant to be pretty sturdy, there are people running mutiple low imp injectors per bank, have a squint throu the link below,

Personally I'd try some 5ohm resistors and see what its like, the resistors migh change the opening closing characteristics, but iirc you can get a quick and dirty working figure by changing the no of squirts and adjusting the dead time until the afr stays the same,

the main thing is that they actually open, but thats easy to test by stuffing an injector on a compressor and using the ms injector test mode.



http://www.msextra.com/forums/viewtopic.ph...er+bank#p177188

Schrödinger's cat - so which one am I ???

There are people using the p&h board successfully with LPG injectors and there are others (like the one in the link above) that have never been able to make it work. The problem is that there are different ones and it seems like each setup is different even with what should be the same injector characteristics. I don't have personal experience with any LPG injector so can only go by what has been reported to me.

The advantage of using the p&h injector drivers is that you can have sequential injection (which some claim is very desirable in an LPG setup) and you also have a more consistent behaviour than with resistors. When using resistors, you need to choose a value that will be low enough to allow the injectors to open under all conditions and this results in having a higher current than needed under normal conditions. With p&h drivers, you get full battery voltage to the injectors for the peak phase then you have a reduced voltage to keep the injectors open during the hold phase.

As Rod mentioned, the chip I use has a fixed 4:1 peak/hold ratio which is not ideal for LPG injectors. However, it is possible to use them by changing the current sense resistor to a lower value to have the higher hold current needed and you also need to change the time out resistor to have a longer peak phase.

Jean

http://www.jbperf.com/

hmmm lots to think about there ,thank you rod and jean , very helpfull info .

i think that i am tending towards the 5 ohm resistors ,and see how i go ,then if that fails step over to trying a pk and hold setup .

i have now ordered my injector plugs ,and a load of piping and filter for the lpg feed to the rail.

now researching a temp sensor for the rail ,i would like to use a exposed resistor iat sensor due to its faster response , but am concerned about the shock of the cold(at first startup) lpg fracturing it .
on the other hand i could use a normal lpg sensor ,which is in a brass body ,so would respond more slowly .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I don't think you should go over 3 Ohms if you want to make sure the injectors open correctly.

Jean

http://www.jbperf.com/

jean ,would that not put me over the 2 amps they talk about in the manual as the limit ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I'm not sure what you refer to but there is no hard limit of 2A. At best it is a recommendation and this certainly would not apply to LPG injectors that require a higher hold current and take a lot time to open.

If you look at the link you posted, the guy is using 1 Ohm resistors. I wouldn't go that low but going with a too high value will mean the injectors won't even open during a cold start due to the low battery voltage under those conditions.

Resistors are always a compromise: a high value means less current and power dissipated in the injectors but a high possibility of the injectors either not opening or not staying open under some low voltage conditions; a low value will mean the injectors always open (and do it faster) and stay open under all conditions but you have more power (and heat) dissipated in the injectors and drivers. So you need to choose a resistor value somewhere in between two extremes depending on your setup and what you're more comfortable with.

http://www.jbperf.com/