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PostPosted: Mon May 05, 2014 10:38 am 
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Jason, I have checked and found that MS2 and above running the 'extra' version of the firmware support 'staged injection'.

Since I have not done this on my install, I have had a brief look on the net, and it appears that a lot of people are running this on turbo'ed setups (supercharger should be the same). They tend to use two of the same size injectors, sized so that the 1st injector is running a decently wide pulse width at idle for idle stability. The software allows many ways to bring in the second injector:

1. RPM... at a given RPM the 2nd injector is brought in along with the 1st injector;
2. MAP... at a given manifold pressure the 2nd injector is brought in along with the 1st injector;
3. TPS... at a given throttle position the 2nd injector is brought in along with the 1st injector;
4. Duty... at a given injector duty cycle percentage the 2nd injector is brought in along with the 1st injector;
5. Table... at a given MAP & RPM as defined in a 6x6 table, the 2nd injector is brought in along with the 1st injector;

I like the Duty % method as it allows you to clearly define a cutoff point e.g. at 70% the 2nd injector is brought in. There is other settings that define things like gradual transition between injectors and over how many ignition cycles etc etc.

Do you roughly know how much BHP you will be producing at the flywheel?

Jim

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PostPosted: Mon May 05, 2014 10:48 am 
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As a side note, the Rover MPI (MEMS system) runs the fuel pressure at 2.5 Bar ~36PSI so if using an MPI in tank pump, the selection of a suitable injector flow rate would have to be done at this pressure or less if you have an adjustable regulator.

Jim

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PostPosted: Mon May 05, 2014 11:20 am 
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Me again Jason. Could you open up the MegaSquirt and take a high resolution picture as close as you can get to fill the whole picture frame, of both sides of the board. This will help me determine what may be needed to get the MS working with injection, fuel pump control etc.
Also where was the MS purchased from, and was it a full kit, and if so do you have a bag of left over components that weren't fitted because you initially only wanted wasted spark ignition.

Also I have a JimStim which allows me to stimulate (sounds dirty doesn't it!) the MS on the bench. See http://www.diyautotune.com/catalog/jimstim-15-megasquirt-stimulator-wheel-simulator-assembled-p-178.html This will allow me to see if any mods etc are working before sending back to you.

Jim

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PostPosted: Mon May 05, 2014 11:53 am 
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standard MS3 on a V3 board will run 2 injectors without any mods - straight off the INJ 1 and INJ 2 outputs... as long as it was built complete & nothing left off as you say Jim.

I'm currently using a pair of 440cc low impedance injectors in batch and am getting too high on the duty cycle at high load/RPM, and too low at idle and overrun. I plan to try out staging (for the low side) on the dyno some time this week, and will try to find some ~550cc squirters to address the high side. Will have similar output - about 100hp at the wheels

There's a bug in the current (& presumably previous) firmware with duty based staging - they recommend using table based

SPi or MPi tank pumps are useless - if you have either of them, chuck them and put a proper pump under the floor.

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PostPosted: Mon May 05, 2014 11:58 am 
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jb007's PM wrote:
One thing to look out for is also the location of your MAP sensor take off. Don't use the SU's vacuum take of, even if its on the manifold side of the butterfly. It is a very compromised vacuum source as I found out. Since you are looking at a Speed Density system, the MAP signal is very important to the success of the smoothness and drivability of the car. I know this as I found out the hard way.

It looks like you have good fabrication skills (something that I don't) so put the MAP takeoff at least an inch away from the butterfly if you can.


que? the MAP takeoff needs to be on the hot side of the blower, otherwise you can't adjust your fuelling and drop timing according to boost

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PostPosted: Mon May 05, 2014 11:59 am 
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Thanks for that, Jason will have to follow up on the pump etc. I'm trying to find out from Jason what the previous fellow installed on the PCB. Also if Jason is going to use low or high impedance injectors, this will effect whether the flyback PWM damping circuit is installed if low impedance injectors are installed.

Also, what type of spray pattern should he go for, or doesn't it matter since it will be atomised by the screws in the SC?

Jim

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PostPosted: Mon May 05, 2014 12:03 pm 
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simon k wrote:
jb007's PM wrote:
One thing to look out for is also the location of your MAP sensor take off. Don't use the SU's vacuum take of, even if its on the manifold side of the butterfly. It is a very compromised vacuum source as I found out. Since you are looking at a Speed Density system, the MAP signal is very important to the success of the smoothness and drivability of the car. I know this as I found out the hard way.

It looks like you have good fabrication skills (something that I don't) so put the MAP takeoff at least an inch away from the butterfly if you can.


que? the MAP takeoff needs to be on the hot side of the blower, otherwise you can't adjust your fuelling and drop timing according to boost


Doh! You're right, my comments only apply to a naturally aspirated setup. So what MAP sensor are you running in your MS?
Jim

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PostPosted: Mon May 05, 2014 12:16 pm 
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simon k wrote:
SPi or MPi tank pumps are useless - if you have either of them, chuck them and put a proper pump under the floor.


Can you elaborate? I have a SPI pump as I run low pressure ~12PSI. I know you can get Walbro http://walbrofuelpumps.com/255lph-walbro-gss342-intank-fuel-pump.html or uprated APS ones here on Ebay http://www.ebay.com.au/itm/APS-GSS342-Walbro-Type-Uprated-Fuel-Pump-For-Rover-Mini-1992-1-3-342255-/360741574775

Would these be better than the original as it would mean just replacing the pump in the tank? :?:

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PostPosted: Mon May 05, 2014 1:20 pm 
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jb007 wrote:
Doh! You're right, my comments only apply to a naturally aspirated setup. So what MAP sensor are you running in your MS?
Jim


just the normal 1 bar on the board

jb007 wrote:


that one would make sense - if "... THE ORIGINAL PUMP IS A GSS342 WALBRO 255 TYPE PUMP"

I just don't see the point in putting in a Rover tank with its issues when the standard tank with a couple of fittings welded on lets you use an off-the-shelf VL turbo etc. type pump.

jb007 wrote:
Also, what type of spray pattern should he go for, or doesn't it matter since it will be atomised by the screws in the SC?


correct, you wouldn't think it'd matter, but I've been steering away from anything with a weird pattern and getting an open cone... though I'm currently only using some I've borrowed

jb007 wrote:
Also if Jason is going to use low or high impedance injectors, this will effect whether the flyback PWM damping circuit is installed if low impedance injectors are installed.


hope its installed - opening times for high impedance cut in to the opening times quite a lot. If he has a bag of bits, put the lot on...

this fella is on a similar track too - viewtopic.php?f=3&t=83512

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PostPosted: Tue May 06, 2014 8:18 am 
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Simon can you tell me why the mpi pump is no good? Was hoping to use as much of my current set up as possible.

Thanks

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PostPosted: Tue May 06, 2014 2:17 pm 
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injectors are all rated at 45psi, 36psi is running them a long way below that, so you have to buy a bigger flowing injector than what the numbers say, and I reckon you'd get funny effects on droplet sizes. Injectors don't specify a "working pressure range", only their flow rate at 45psi. Go a long way outside that and you're just guessing.

The MPi mini would have (probably) been specified and designed to run at optimum efficiency with the specific injector they're using, at specific pressure. You want something completely different, so you're much better off designing your system to run at "industry standard" specifications.

I could be taking out of my arse too...

turbominis.co.uk has a lot of useful stuff - see if anyone on there is using an MPi tank pump

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PostPosted: Tue May 06, 2014 2:24 pm 
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if I was you, I'd try to inject into the hot side manifold - port injection - you'd need to deal with the whole siamese port issue, and probably run two pairs of injectors (small primaries and big secondaries), but should end up cleaner.

I think someone on turbominis has done it

I plan to get to that point eventually, but its a way off

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PostPosted: Tue May 06, 2014 3:40 pm 
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here you go for an injector pressure conversion - scroll all the way to the bottom

http://www.smartfireinjectors.com/ebay/ ... chart.html

says if you want to run a 440cc injector at 36psi, you'll only get 400cc out of it

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PostPosted: Tue May 06, 2014 5:04 pm 
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Hi Simon & Jason.

1. The reason I put a link to the Walbro GSS342 is that it can operate at PSI's over 80PSI and even more. It is a drop in replacement for the MPI pump. Jason I believe already has a Rover MPI tank, so it would be logical for him to just change the pump. One gotcha is there is a lot of fake Walbro pumps on ebay, so be careful.

2, Not all injectors are rated at (3 Bar) 45PSI for example see here: http://www.bosch.com.au/car_parts/en/downloads/fuelinjectors.pdf notice that some of them are rated at a operational pressure of 2.5Bar even though they give the flow rate at 3 Bar. Jason I can email you a MS excel spreadsheet that will calc the flow rate for a given pressure or use the the link Simon has linked to.

I agree with you Simon that it would best to run the injector at the recommended PSI, things like dead time is usually only (if at all) specced at the rated flow.

Cheers
Jim (As of today on VIC CPS plates!) :D

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PostPosted: Tue May 06, 2014 7:10 pm 
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jb007 wrote:
As a side note, the Rover MPI (MEMS system) runs the fuel pressure at 2.5 Bar ~36PSI so if using an MPI in tank pump, the selection of a suitable injector flow rate would have to be done at this pressure or less if you have an adjustable regulator.

Jim

no, the MPi runs at the regular 3bar, measured above manifold pressure. thats why you have lower fuel pressure at idle and part throttle. this is done to keep the duty cycle reasonable high.

select the fuel pump carefully. if its to big it will heat the fuel unnecessary, will give trouble if the regulator and return line are to small, and it it will draw lots of power with the need of thick wires.
the injection tank won't give any trouble, the tubing is big enough to support large amounds of fuel.
the MPi pump has a internal pressure limit of 5bar and considered to support 160HP, but at 3 bar. higher pressure will give less flow.

injector dead time is not specced with the normally quoted static fuel flow.

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