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PostPosted: Tue Oct 30, 2012 8:09 pm 
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thanks rossko ,

does that mean that the temp sensor on my prins vap is measuring gas temperature ?

re referencing the gas pressure to map, there appears to be a pressure referencing input stub on the vapouriser , my intent was to connect this to the inlet manifold so it picks up manifold vac/pressure , is this what your talking about ?

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PostPosted: Tue Oct 30, 2012 8:32 pm 
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robertXX wrote:
does that mean that the temp sensor on my prins vap is measuring gas temperature ?

No. It is safe to unscrew it, so you can see it is poking in the water jacket. It won't give any useful guide to gas temperature, it used for changeover control (something else the MS can't do as standard). You won't need that at all if you are making a gas-only car.

A real Prins system has temp (and pressure) sensing built into a vapour filter housing.

robertXX wrote:
re referencing the gas pressure to map, there appears to be a pressure referencing input stub on the vapouriser

No, that is a PRV - a safety valve. You can plumb that into the manifold, or plumb it down to the fresh air, or leave open - just so long as any gas vented under fault conditions (a frozen vap, say) gets dumped somewhere safe.

Unless you've chanced on an already modified unit, which it doesn't look like, the pressure reference on yours takes the form of a pinhole near the adjuster. You need to block that off - I wind in a self-tapper in a blob of araldite, and cut off flush. Then drill a new hole and fit nipple in the 'slopey shoulder' of the central boss. You need to strip the vap or the diaphragm will be ruined.
It's stupid not to fit a new rubbers kit while its in bits.
Occasionally the screws seize and shear, and the unit may become scrap. That one is quite elderly from the label, so it is a real risk.

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PostPosted: Tue Oct 30, 2012 8:52 pm 
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some super advice there rossko ,thank you .

i will drill the case after taking it apart as gently as i can .

i wonder , if i fit a temp sensor in the end of the valtek fuel rail., whether a iat sensor or a cts would be best , i am concerned about the exposed resistor type iat sensor breaking if faced with a shot of cold lpg ?but , on the other hand ,a cts would have a slower response time .

ref pk and hold , i can fit a set of 4 resistors in the injector feeds to limit current .but am also investigating the pk and hold function in ms2.
also researching the correct connectors for the valtek injectors .

regards robert.


Last edited by robertXX on Tue Oct 30, 2012 9:23 pm, edited 1 time in total.

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PostPosted: Tue Oct 30, 2012 9:08 pm 
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http://www.ebay.co.uk/itm/Superseal-con ... 3a5c878154


gosh ,well that took a bit of finding !!!


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PostPosted: Tue Oct 30, 2012 9:51 pm 
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Image

map stub shown well here .


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PostPosted: Tue Oct 30, 2012 10:33 pm 
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You could always buy a temp sensor
http://www.tinleytech.co.uk/acatalog/Mu ... Hana_.html
but I'd be worrying about what you could usefully do with it in MS setup.

robertXX wrote:
ref pk and hold , i can fit a set of 4 resistors in the injector feeds to limit current

You know that's a bodge! I actually don't think you'll persuade those injectors to open against the Prins' nominal 2 bar without real peak-n-hold drive.

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PostPosted: Thu Nov 01, 2012 8:01 pm 
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Yo will need to fit the resistors to make the system work. MS is popular in the Volvo scene and classic Volvo's use low resistance injectors and to make them work with MS you need to use resistors.

If you search on the Turbobricks forum there is someone (in Holland?) who is running MS and also reunning is LPG injctors from it. He cold probably help you out with correct injector settings in the MS software.

The very early injection systems did not use a pressure sensor or gas temp sensor and relied on Lambda correction to make the adjustments needed. From memory when I looked into the MS software would not support a gas pressure sensor or gas temp.

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PostPosted: Fri Nov 02, 2012 5:20 pm 
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classicswede wrote:
Yo will need to fit the resistors to make the system work. MS is popular in the Volvo scene and classic Volvo's use low resistance injectors and to make them work with MS you need to use resistors.

If you search on the Turbobricks forum there is someone (in Holland?) who is running MS and also reunning is LPG injctors from it. He cold probably help you out with correct injector settings in the MS software.

The very early injection systems did not use a pressure sensor or gas temp sensor and relied on Lambda correction to make the adjustments needed. From memory when I looked into the MS software would not support a gas pressure sensor or gas temp.



thank you classicswede , i had forgotten about that forum ,so i will go and have a look . i have a wide band lambda on the car already ,so i can use that for some closed loop stuff as well. i am considering using the water temp feed for the engine plugged inot the gas rail ,and see how that works .


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PostPosted: Fri Nov 09, 2012 6:55 pm 
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i had to solve the problem of how to fix this super sensitive air temp sensor in this rail..

Image

so i gave up on the wierd metric 1mm thread in the end ,and used an alternative approach ...

bought a cheap t piece ,and lathed a flat on one side...

Image

Image

this allowed me to fit the sensor in the side ,and have it directly in the gas stream

Image

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then i used the third leg ,with a machined bung in ,to mount the pressure guage

Image

Image

and last of all , i did the pressure feed to the reducer ,and blocked the old breather hole .
Image


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PostPosted: Fri Nov 09, 2012 11:14 pm 
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I'll throw a fly in the ointment. Propane can be cruel to plastics and rubbery seals; confident about dunking an air sensor in the gasflow? How about an inspector?
If it is okay it should work brilliantly in terms of response time.

The absolute pressure gauge is of limited use, you'll be interested in differential pressure across the injectors. That gauge rated for propane ... ?

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PostPosted: Sat Nov 10, 2012 9:14 am 
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http://new.ametek.com/content-manager/f ... Gauges.pdf


phosphor bronze bourdon tube , so will be fine .

ref temp sensor ,
considering its normal environment , i think its seal will be neoprene or buna .n , again fine for lpg , ref the physical structure of the sensor and surrounds ,i considered that it may be prone to cold shock fracture ,,but after checking its response time and temp range , and the characteristics it must have to achieve those statistics ,decided it was likely to survive .

i do research these things , but not putting all research on this thread , i felt it would be too windy . :)

injector resistors(boo says ross!,yay!says classicswede :D ) arrived this week ,so today i am starting adapting the astra wiring loom to connect the car to the megasquirt 2.

oh ross i forgot the address your query about the differential pressure , i have another guage on the inlet, boost and vacuum,so by comparing the two i can monitor the crossover pressure and the response time on my chassis dyno .


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PostPosted: Tue Nov 13, 2012 8:59 am 
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ok doke , bit of a test sesh ,

http://youtu.be/2GKHdI89Xfo

http://youtu.be/tTq4NEFhbpU


up to 30 psi ok with he 2.7 ohms. up to 44 psi , ok with the 1.8 ohms . max rated pressure from the regulator is 38 psi.

also checked temp rise , in 2 mins ,the 2.7 ohm rose from 14c to 25c.
the 1.8 ohm rose from 14 to 55c .not really hot to the touch .

amps with the 2.7 ohm were 1.99 A
with the 1.8 ohm were 2.47 A
with no resistor 3.39 A

also a bit about temperatures..

http://www.hondata.com/techlowohminjectors.html


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PostPosted: Tue Nov 13, 2012 11:56 am 
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How do you know it's okay? These are dynamic devices, whether it takes 0.5 or 1.5mS to close or open when current is turned off/on makes a difference. Worth a try for sure, but there are good reasons why peak-n-hold is used commercially and series resistors were abandoned in the 1980s

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PostPosted: Mon Nov 19, 2012 6:55 pm 
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Volvo kept the system to the late 90's with the 940 turbo.

His best advice will come from tuners who know the megasquirt system. I'm sure getting the injectors driven correct will need some thinking about but the advice should be out there.

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PostPosted: Thu Nov 29, 2012 6:05 pm 
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progress..

Image


Image


Image


Image

:D


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PostPosted: Sat Jan 12, 2013 5:01 pm 
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well finally connected it all up today , and oh yes , what a damp squib!
1st thing to notice was 31 psi pressure , so a bit high , persevering, i cranked it over ,got a few coughs etc ,but nothing to say ''it runs ''
so hoicked out the lead to have a chat with the ms2..... no connection ,then momentary connection then nothing ,so i think i may have a duff serial lead .so i could not turn the req fuel up or down to get it to fire .the noticed gas pressure now at 60 psi , oh dear .

so either i have had a bit of a back fire and it has popped a bit more gas in there to the level thet the inj cannot bleed it off on cranking , or the regulator is leaking ... it all looked fine when i took it apart but i suppose i had better have another look.. now back on the ring system . :?


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PostPosted: Sat Jan 12, 2013 9:13 pm 
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Dear Robert,

You can always bleed off the gas pressure by opening the injectors - just put 12v on one side and ground the other. When done, reconnect the harness.

Resistors should work fine, albeit lead to slightly longer injector times when compared to a dedicated peak and hold board. Your MS2 unit has two injector driver channels on the main board and this can easily drive the injectors plus resistors (a high impedance load). Each channel can actually handle up to six low impedance injectors outright, so you may not need resistors at all. In this case, the two channels are set to run in PWM mode. Read the manual.

Your Keihin injectors will work happily in peak and hold mode - 6 amps to open - 1 amp to keep open. You can run them from a standard lm1949 circuit if you drop the sense resistor value down a bit.

You do want to pay attention to Ross's comments re plastics when exposed to lpg.

Since you don't have a petrol setup at all, MS2 will probably not run out of inputs as it would be right on the limit of its capabilities to handle two different types of fuel. An upgrade to MS3 from MS2 would give you much more functionality and proper dual fuel support.

Unlike everyone else, with MS you'd be able to set your own advance curves however you want, rather than be restricted to running the lpg spark retarded to the petrol spark settings like everyone else does with their piggyback systems. Properly tuned, your sytem should outperform all of the others. You also get full access to all of the ECU parameters, which the isn't the case with the twin ECU setups.

kind regards
Marek


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PostPosted: Sat Jan 12, 2013 9:44 pm 
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marek wrote:
You can always bleed off the gas pressure by opening the injectors - just put 12v on one side and ground the other. When done, reconnect the harness.
Although with the sort of pressures he's talking about, the injectors won't be able to open against the pressure.

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PostPosted: Sun Jan 13, 2013 4:28 pm 
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thanks marek , all good points .

as gilbert says , the inj wont open above ,according to my testing no the bench ,around 45 psi , so that 60 psi was well over there openning threshold .

regards
robert


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PostPosted: Sun Jan 13, 2013 5:01 pm 
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Dear Robert,

I wouldn't be too hasty in connecting up power to the gas solenoids until you have obtained the correct pattern as viewed in a composite log via Tunerstudio. Once the ECU has a good crank signal and you have then verified the timing as rock steady with a timing light, you can move to the fuel side of things.

kind regards
Marek


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