Hi there,

What have I missed?

I am running gsxr1100 with EFI (gsxr600 TBI) controlled by megasquirt (MS2), I can log using this with my LC-1 measuring AFR's.

Regarding fueling I have an intank Walboro 255 (theoretically 255litres/hour), and 4x s2000 gen1 injectors (theoretically 390cc/min each at 43.5psi), I have a FSE fuel pressure regulator and a cheap pressure gauge (visual only). With the MS I am running 2 squirts per cycle.

So, I've been tuning up using dual table (multiplied MAP and Alpha-N), the tune is coming together, it comes on boost enthusiastically, idles nicely and it seems to be quite promising.

The (present) problem that I have is that I am getting >100% duty cycle on my injectors even at relatively modest power demands (i.e. 8psi of boost 7.5kRPM and 100% throttle open). Clearly if I am going to rev higher (i.e. 11k red-line) I am going to be running lean which is not going to work for long


Previously I have tried to address this by increasing the fuel pressure (presently at 4.5atm+MAP). This doesn't seem to have helped.


So, I don't understand. The injectors are good for ~1.5litres/min at 43.5psi, the fuel pump is good for 4litres/min.
1.5 litre/min of fuel should give me about 240bhp, so what have I done wrong? and these s2000 injectors are used on Busa turbo (so fruitier than my old engine).


My thoughts.
1) Fuel pressure gauge dodgy
2) Low volts at fuel pump
3) Blocked fuel pump inlet filter
4) Fuel injectors not as described (2nd hand)


My thinking is that I might measure the voltage at the pump to look for lost volts (the Walboro is a turbine type so will be sensitive to low volts). Next stick a video camera on the pressure gauge as a sort of secondary logging to see if there are pressure drops. Drop the engine to 1 squirt per cycle which will squeeze some more out of the injectors (less dead time for opening/closing).

Any thoughts appreciated. I am hoping that I have missed something obvious.


Thanks,

Matt

Send the injectors off to get them cleaned. I sent mine to Mr Injector, he measured them and they were awful. Cleaned and refurbed


Cost about £45

Dont think the voltage at the pump has anything to do with the duty cycle.. after all theres nothing measuring how much fuel is going in.. however..

Voltage drop at the injectors can slow the opening therefore reducing the fuel going in..

My other thinking is.. are you using a lambda fir the AFR closed loop? If this is closed loop controlling the fueling I would look there first.. are you able to communicate to the LC1? Is the lambda set up on the right channel?

I'm just getting back onto my MS2 applying it to a Rover V8....

ask a stupid question you are rising the fuel pressure with boost by having the small pipe conected to port pressure?
a fixed pressure system will not work boosted.

if your pump is not keeping up you would see it as fuel pressure drop

are you also looking at actual inj duty cycle in ms or you may not have your inj settings right like pwm set too low or somthing?

Good thoughts:
Just to add some details

My pressure regulator is MAP referenced (it has a port on the top that is plugged into my MAP line)
I am not running closed loop, so the AFR is simply diagnostic.
Megasquirt outputs a dutycycle (which is the desired pulsewidth as a fraction of the available time) which is what I am talking about
My logic is that if you autotune then all megasquirt can do is increase opening times (via the fuel map), if you run out of fuel pressure/flow then the table values keep increasing but to no avail.
I did clean and DIY test the injectors before I put them in (fuel injector cleaner and the ultrasonic cleaner at work, shh!)


My concern about pump volts came from this:

Showing the higher voltage gives increased flow, which made me wonder what would happen at reduced voltage.

Oh and injectors are 14Ohm, so no PWM for me. I am driving them all off one driver though, so remaking the loom is a good idea to speed up the switching (and easy too).

Thanks for all these good ideas.

all on 1 driver? so you are running batch fire? this may not be so good for your fuel pressure regulation
could you not use both of your drivers (1+4 & 2+3) alternating
i also run a 15A fuse for each bank and twined up feed cables

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Originally posted by baz-R
all on 1 driver? so you are running batch fire? this may not be so good for your fuel pressure regulation
could you not use both of your drivers (1+4 & 2+3) alternating
i also run a 15A fuse for each bank and twined up feed cables

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I hope your batch firing - if not you'll be firing nothing on every other alternation. That would half your available fuel.

hi
check your inlet pipe from the tank to the pump.
maybe isn't strong (if its rubber pipe) and you have a hugh vaacum from this pump.
this pipe is right to be plastic or metalic not rubber.

Get rid of the FSE FPR and fit a fixed Bosch 3.5 Bar reg. This is what you should be running. What power are you expecting from the engine/turbo combo?

sounds like you have got too much resolution in your fuel table. im guessing that because your engine is pretty small the required fuel value is pretty low.

forget duty cycle on the injectors for now and look at the pulesewidth. at idle you should be at around 2.5ms any lower and i doubt it will run well.

just for a reference my required fuel is around 10 on the 2.0 turbo saab, i would guess you will need to be in that ball park if your looking at making 200hp upwards. it will make getting a good idle a little harder but should give you a bit more fuel up top.

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Originally posted by jeffw
Get rid of the FSE FPR and fit a fixed Bosch 3.5 Bar reg. This is what you should be running. What power are you expecting from the engine/turbo combo?

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Originally posted by ashg
sounds like you have got too much resolution in your fuel table. im guessing that because your engine is pretty small the required fuel value is pretty low.

forget duty cycle on the injectors for now and look at the pulesewidth. at idle you should be at around 2.5ms any lower and i doubt it will run well.

just for a reference my required fuel is around 10 on the 2.0 turbo saab, i would guess you will need to be in that ball park if your looking at making 200hp upwards. it will make getting a good idle a little harder but should give you a bit more fuel up top.

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Originally posted by dimlaz
hi
check your inlet pipe from the tank to the pump.
maybe isn't strong (if its rubber pipe) and you have a hugh vaacum from this pump.
this pipe is right to be plastic or metalic not rubber.

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Originally posted by matt_gsxr

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Originally posted by baz-R
all on 1 driver? so you are running batch fire? this may not be so good for your fuel pressure regulation
could you not use both of your drivers (1+4 & 2+3) alternating
i also run a 15A fuse for each bank and twined up feed cables

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Interesting, I am running 2 squirt per cycle and the RPM's are always going to be above 1k. This has been working like this for a long time but I have worried about the reliability of my FPR before.

Anyway, I am at this very moment building a second injector loom (1+4 on 1 driver and 2+4 on the other). I already wired up the drivers to MS as I was running staged injection and I have all the parts to hand, so I can build this and test tomorrow.

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Originally posted by coozer
Dont think the voltage at the pump has anything to do with the duty cycle.. after all theres nothing measuring how much fuel is going in.. however..

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So, the plot thickens my sleuth-like friends.

I measured the flow rate in the return line (fuel system is Tank-pump-longhose-fuelrail-regulator-returnline) and in 30seconds it filled a 4pint milk carton. I did this by mass and got 1440grammes in 30seconds, so 4litres/minute.

4litres/minute = 240litre/min. And all this was with the engine off (so volts around 12v rather than the running value of 13.5v), which puts me about on the line in the graph (above) depending on whether the y-axis is 'merican or Imperial gallons.


So to my mind this eliminates:
Voltage at the pump
Blocked hoses and filters


Which leaves me with dodgy injectors, or dodgy pressure regulator;

The SBD site does suggest that these FSE FPR are good only to 215bhp ( http://www.sbdev.co.uk/Fuel_Systems/Fuel_Pressure_Regulars/Fuel_Pressure_Regulars.htm ), and I don't trust the pressure gauge (it came with a previous super cheap FPR).

And the injectors came from a bloke in the USA who was 'breaking an s2000'.



Time to rebuild my fuel injector testing jig (fire brigade on standby!)

Matt

Have you checked the plugs to ensure all cylinders are running approximately equal AFR?

Is the engine definately not running rich when it hits 100% (ignoring the AFR meter, e.g. black exhaust smoke etc)?

[Edited on 19/5/13 by MikeRJ]

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Originally posted by matt_gsxr

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Originally posted by baz-R
all on 1 driver? so you are running batch fire? this may not be so good for your fuel pressure regulation
could you not use both of your drivers (1+4 & 2+3) alternating
i also run a 15A fuse for each bank and twined up feed cables

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Interesting, I am running 2 squirt per cycle and the RPM's are always going to be above 1k. This has been working like this for a long time but I have worried about the reliability of my FPR before.

Anyway, I am at this very moment building a second injector loom (1+4 on 1 driver and 2+4 on the other). I already wired up the drivers to MS as I was running staged injection and I have all the parts to hand, so I can build this and test tomorrow.

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The DutyCycle that my Megalogviewer is putting out is equal to:
[Field.pulseWidth] * [Field.RPM] / 600

So basically the pulsewidth divided by the time for one crank cycle.
I think the opening time is wrapped into the pulsewidth.

No opportunity for high power tests of revised injector wiring, but hopefully I can test the injectors this week and maybe source a replacement FPR.

Matt

The other problem you can see is pressure drop along the rail at high flow rates which would lean out the cyls as you progress from the pump. What's the bore on your rail?

With a small ish rail, 4 big injectors firing at once and a FPR with a pretty small flow, you must be getting a considerable drop in fuel pressure, can you see fuel pressure whilst driving and boosting?

Fuel can only flow to your injectors as fast as it can leave your rail through your FPR, invest in one with a much higher BHP/flow rating

Going from all 4 firing to 2 and 2 will help you out.

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Originally posted by coyoteboy
The other problem you can see is pressure drop along the rail at high flow rates which would lean out the cyls as you progress from the pump. What's the bore on your rail?

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we have seen small injectors "max out" according to tunerstudio on high revving engines, we did a cosworth YB NA some years ago, made 262BHP at around 9K, we used 412cc injectors but these where 90% at high RPM - changed them for 625cc to reduce duty to 60%
In theory the 412cc injectors are plenty big enough for that sort of power....

so, on higher revving engines its not always a fuel delivery issue but a timing issue - at high RPM there is not enough time to open, then close a small injector. A larger injector does not require as much open time to deliver the right amount of fuel therefore more time is available.

If i was you i would use larger injectors or more fuel pressure (and lower reg_fuel) this will lower the duty.

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Originally posted by BaileyPerformance
If i was you i would use larger injectors or more fuel pressure (and lower reg_fuel) this will lower the duty.

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Originally posted by MikeRJ

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Originally posted by BaileyPerformance
If i was you i would use larger injectors or more fuel pressure (and lower reg_fuel) this will lower the duty.

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The OP has already tried increasing fuel pressure but it made no difference to the required duty cycle, which is why fuel delivery is/was under suspicion.

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Originally posted by BaileyPerformance

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Originally posted by MikeRJ

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Originally posted by BaileyPerformance
If i was you i would use larger injectors or more fuel pressure (and lower reg_fuel) this will lower the duty.

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The OP has already tried increasing fuel pressure but it made no difference to the required duty cycle, which is why fuel delivery is/was under suspicion.

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Increasing the fuel pressure should of course increase injector flow, if it does not then it would point to the pressure not been maintained under high demand.

The point I was making is the req_fuel need to be corrected, increasing the fuel pressure is the same as increasing the injector size(up to a point) so the size of the injector entered in ms needs to be increased. It's this value and the PW that used used to calculate the duty cycle.

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Have you got a fuel pressure gauge? If we have any suspected fuel delivery problems we install an in-line gauge so we can confirm the pressure rises with boost, I know it's hard to do on the road, but maybe it could be rigged up above the bonnet line. As I'm sure you know fuel pressure is likely to be fine at low revs, but high revs and with boost it mite be dropping. Have you ended up with numbers bigger than 180 in the VE table? That's clue that the fuel pressure is dropping.

Good questions.

Have a pressure gauge (4.5bar)? yes
Measuring the flow out of the return line and I get 4litres/min.

I think you are right that I might be losing pressure at load.

Presently running multiply tables so the 180 number (though helpful) is masked by all that complexity, but that is a good tip.

I assume you are running alpha n as the primary table them map as a secondary table to add fuel under boost? If so just add the two numbers at the higher load sites to see if your over 180 ve.

Measuring the return is not really going to tell you anything, if your base pressure is 3bar then a 4.5bar gauge will be just the job. Assuming your fpr is 1:1 you should see 3.5bar of fuel pressure at 7psi of boost. If this is maintained at high rpm but you duty cycle is still too high then you need more base pressure or bigger injectors. The problem with running high base pressure is it puts more strain on the pump, so bigger injectors is the best way to go.

Can you post a pic of your fuel system?

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As an update from the original question; I measured the flow out of the bottom of the regulator (i.e. return line) and I get 4 litres/min so I am fairly sure that my problem isn't the pump. Unless it is doing something funny when the injectors are going full chat.

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I do wonder if this is your injectors Matt, as discussed I'm running 600cc ones to ensure there is some overhead.

Depressurized the fuel rail tonight so I could remove the injectors for testing.

The pressure gauge still reads 4atm, but there is no pressure.

I suspect I need to get a replacement gauge and then start this all over again. Amazing that it worked at all really.
Gauge came with my early cheap pressure regulator that came from McGill. Very annoying but self-inflicted.



Thought I might as well check the injectors. Perfectly balanced, and consistent flow patterns (all the same, although these are quite old fashioned so more of a squirt than a mist). Only 330g/min of water (didn't fancy using fuel), but I tested a set of gen1 Busa ones on the same rig and got 230g/min. So not too bad. I thought the s2000 ones were rated at 360 or 390cc/min. Looks like I was sold Prelude 2.3vtec ones.




I think the source of my present problems is fuel pressure (probably was running 1atm), but I may also run into the injector limits before I reach my target power. Time will tell.

Matt

Interesting, I thought you would have noticed this with the power off....Mine reads 0 with no fuel pump running and only goes to 3.5bar when the ignition/fuel pump is operational.

Some pressure regulators/pumps retain pressure in the system with the pump off, some don't.

We always use Mondeo/Focus 3.8bar regs on custom mounting or Weber Alpha. All cheap ebay one are total rubbish, sometime dangerous as the diaphragms are weak and can rupture causing fuel to leak out the case and out the vac port into the engine.

FSE power valves are also poor, these do not leak or fail but the fuel pressure is unstable compared to a Ford or Weber reg, i have 3 of these under the bench i have removed form customers cars destined for the bin.

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Originally posted by matt_gsxr
Thought I might as well check the injectors. Perfectly balanced, and consistent flow patterns (all the same, although these are quite old fashioned so more of a squirt than a mist). Only 330g/min of water (didn't fancy using fuel), but I tested a set of gen1 Busa ones on the same rig and got 230g/min. So not too bad. I thought the s2000 ones were rated at 360 or 390cc/min. Looks like I was sold Prelude 2.3vtec ones.

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Originally posted by MikeRJ

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Originally posted by matt_gsxr
Thought I might as well check the injectors. Perfectly balanced, and consistent flow patterns (all the same, although these are quite old fashioned so more of a squirt than a mist). Only 330g/min of water (didn't fancy using fuel), but I tested a set of gen1 Busa ones on the same rig and got 230g/min. So not too bad. I thought the s2000 ones were rated at 360 or 390cc/min. Looks like I was sold Prelude 2.3vtec ones.

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Water has a higher viscosity than petrol, so the injectors will naturally flow less when using water.

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broken gauge

Gauge on kitchen table. Still broken.

New regulator, from these guys http://www.specialist-components.co.uk/ also on the kitchen table.


new regulator

Dug out a spare gauge (from tyre inflater) and found that I had been running 1atm of pressure from the old adjustable regulator, oops.

It does explain a few things;
why when I dropped the fuel line pressure from 5atm to 4.5atm [i.e. 1.5atm to 1.0atm] and increased the fueling by 5% to compensate that it all went very lean)
why on the over-run I couldn't get enough fuel into the system (the vacuum meant the residual fuel pressure must have been about very low owing to the MAP compensation).

It might explain why I was struggling to get nicely behaved fueling, although that might still be something else.

Running better now with a fixed 3.5bar (OEM Bosch) regulator, and I had to decrease the fueling by around 50%, so I am optimistic that I am moving towards a solution.


Interestingly with 3.5atm of pressure my fuel pump only outputs 2litres/min (detected via the return line to tank). 2litres/min is more than enough, but interesting how much it decreases (given that it is rated at 255litres/hour, i.e. 4.25litre/min).

I also replaced the fuel rail, the old one had a poor thread on one end.

Here is a photo:


fixed_regulator

Good stuff, sounds like you've found the solution - fingers crossed!

Funny how you can be bitten by the simplest faults when you trust gauges!

[Edited on 26/5/13 by coyoteboy]

Must admit to liking the fixed Bosch regulators these days. Sounds like you are almost there Matt.

quote:

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Originally posted by matt_gsxr
Interestingly with 3.5atm of pressure my fuel pump only outputs 2litres/min (detected via the return line to tank). 2litres/min is more than enough, but interesting how much it decreases (given that it is rated at 255litres/hour, i.e. 4.25litre/min).

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