MikeRJ
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| posted on 20/5/13 at 07:33 PM |
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quote:
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.
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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BaileyPerformance
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| posted on 20/5/13 at 07:50 PM |
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quote:
Originally posted by MikeRJ
quote:
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.
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.
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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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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matt_gsxr
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| posted on 20/5/13 at 08:56 PM |
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quote:
Originally posted by BaileyPerformance
quote:
Originally posted by MikeRJ
quote:
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.
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.
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.
I completely agree with your logic. I'm still investigating. Bought a new regulator today, and will check the injectors this week.
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BaileyPerformance
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| posted on 20/5/13 at 09:16 PM |
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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.
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matt_gsxr
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| posted on 20/5/13 at 09:34 PM |
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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.
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BaileyPerformance
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| posted on 21/5/13 at 09:35 AM |
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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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coyoteboy
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| posted on 21/5/13 at 10:01 AM |
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quote:
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.
Ah, missed that - ok, that's the rail out then.
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jeffw
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| posted on 21/5/13 at 10:18 AM |
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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.
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matt_gsxr
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| posted on 21/5/13 at 10:19 PM |
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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
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jeffw
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| posted on 23/5/13 at 08:42 AM |
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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.
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matt_gsxr
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| posted on 23/5/13 at 10:14 AM |
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Some pressure regulators/pumps retain pressure in the system with the pump off, some don't.
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BaileyPerformance
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| posted on 23/5/13 at 10:19 AM |
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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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MikeRJ
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| posted on 23/5/13 at 10:43 AM |
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quote:
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.
Water has a higher viscosity than petrol, so the injectors will naturally flow less when using water.
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matt_gsxr
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| posted on 24/5/13 at 01:12 PM |
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quote:
Originally posted by MikeRJ
quote:
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.
Water has a higher viscosity than petrol, so the injectors will naturally flow less when using water.
Cool, this had crossed my mind. but I couldn't find anything on it.
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matt_gsxr
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| posted on 24/5/13 at 01:24 PM |
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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
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matt_gsxr
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| posted on 25/5/13 at 03:37 PM |
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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
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coyoteboy
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| posted on 26/5/13 at 08:04 PM |
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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]
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jeffw
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| posted on 26/5/13 at 09:15 PM |
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Must admit to liking the fixed Bosch regulators these days. Sounds like you are almost there Matt.
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MikeRJ
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| posted on 5/6/13 at 09:47 AM |
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quote:
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).
Now that you have significantly more load on the pump (and therefore a higher current being drawn) have you rechecked the voltage at the pump itself?
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