Japtastic141 Posted March 28 Author Report Share Posted March 28 Well, it's worth a try I guess. Not sure the failure rate on these? Any experience of them? No chance it could be the alternator at high load/rpm? I've only managed to test it at stationary revved up to 5k. One thing I haven't done is look at the waveform it puts out but I suspect it would be ok at idle and high revs and maybe only show an issue when under load + high revs... Only the ECU is seeing the voltage drop but the pump isn't. Wondering what this current draw is that it's seeing. Would the voltage drop at the ECU cause issues? Picoscope all seems to verify pump is working correctly. I can post that here if helpful? Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 9 Author Report Share Posted April 9 Just got back from a few days away and just tested again without ABS + ATTESA ECU connected just in case they were drawing a high current. No change Also tried a run without the fuel cap in case that was at fault. Also didn't make any difference. ECU is still seeing voltage dropping from 13.4ish down to 12.8ish on these high rpm runs. Fuel pump isn't. What can I look for that would be causing this as surely the drop of voltage to the ECU (and probably other electrical items?) is not right? I've checked the earth and positive ECU pins and all seem to check out fine in regards to voltage drop and resistance at idle. Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 10 Report Share Posted April 10 So is your differential fuel pressure problem now solved? Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 10 Author Report Share Posted April 10 Thanks for the reply. No, still the same symptoms since the beginning still exist. Fuel pressure dropping as well as voltage to the ECU. Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 10 Report Share Posted April 10 The voltage reported by the ECU is measured between the power ground plane (example pin 107 or 108) and the main supply on pin 49 & 59. Pin 49&59 are supplied by the ECCS relay. There is only the ecu, CAS and airflow meters connected to the ECCS relay output so very little current, probably <1A. However, none of this is going to affect your differential fuel pressure, so I would focus on solving that first. Slightly low voltage at the ecu is only going to affect the deadtime accuracy by maybe 0.1ms and maybe dwell by about the same, of course it is something that should be fixed before final tuning, but it is unlikely to cause any tuning difficulties. Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 10 Author Report Share Posted April 10 Thanks for that info. Any more help or advice to fixing the fuel pressure issue would be appreciated as I’m all out of ideas. Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 15 Author Report Share Posted April 15 I replaced the new 450lph Walbro fuel pump over the weekend for a Walbro 255lph as Mark mentioned it was worth trying and just in case the 450lph was either faulty from new or too strong for my setup/FPR. This had made no difference. I also bought a Mytivac to make sure I had bang-on control as using the air compressor was a little janky. I re-ran the return fuel test with new the 255lph pump based on the specs given by Walbro at 3 and 5 bar and they come out bang on specification so I'm pretty sure my pump, wiring, fuel lines, FPR and filters are ok (unless I'm missing something?) along with the fact the 5D fuel table works pretty well to add extra fuel when needed so the fuel appears to be there it's just not matching 1:1 with boost from the usual way. I don't want to end up relying on this 5D table as a workaround. Been out for another run. 1st is with boost control turned on, 2nd without. I had a theory that above WG boost could be an issue but doesn't seem to matter. Any ideas anyone? https://drive.google.com/file/d/1pOu0tNKYI0yP2OEIRbYxI2MKNqbw6Hrf/view?usp=sharing https://drive.google.com/file/d/1Uz9X5BJ8wfFlhYyw8ODo-UF2QI3U1qsE/view?usp=sharing Quote Link to comment Share on other sites More sharing options...
AbbeyMS Posted April 16 Report Share Posted April 16 Looking at the logs again, are the log files direct from a laptop log or via the logging memory in the ECU just to know the logging frequencies? The reason I ask and i am sure I have asked this before the RPM and fuel pressure sensor out are terribly unstable, the map sensor signal (output) isnt thou. I find it very hard to understand why the fuel pressure is dropping off even at base boost? can you clarify what base fuel pressure is please , 1- with the pump being run via the test output (so no possible issues with interference etc) 2- with the car running with the boost ID removed from the fuel pressure reg, can these be logged at the highest frequencies (500hz +) please to see whats happening with the outputs please. Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 16 Author Report Share Posted April 16 Hi, All these logs are from a laptop so far. I think I have ECU logging setup correctly now. I've upped the trigger filtering to see if that helps also. I'm having trouble getting the ECU to log with the ignition on and not started so here is a PC log of ignition on and the fuel pump activated by test output and then an ECU log of the car running with boost ID removed. Let me know if this is correct and what you wanted. https://drive.google.com/file/d/1mJn5RO5SuzN2F3IRp28r3LUACWWhKNJO/view?usp=sharing https://drive.google.com/file/d/177C7uUiZP9Au9B7Bu4d8_o7jh4rG2iO-/view?usp=sharing Quote Link to comment Share on other sites More sharing options...
AbbeyMS Posted April 16 Report Share Posted April 16 Okay so the laptop log rate will only be 40HZ , if you log with the ECU it can be up to 1000hz. Ecu to log to ECU with engine off just needs the ECU logging parameters adapted so once the ignition is on it will start logging or you can use a stab of the throttle start to start the logs. Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 16 Author Report Share Posted April 16 Ahh ok, good tip. Did the logs tell you anything? I'll try to get the ECU log of the engine off with the fuel pump on shortly. Quote Link to comment Share on other sites More sharing options...
AbbeyMS Posted April 16 Report Share Posted April 16 Give me a ring please to discuss , Sat at my desk at the moment. Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 17 Report Share Posted April 17 Can you attach a copy of your tune. With the engine off but pump running, if you feed say 20psi into your FPR with the mityvac, does the f press reported in the ecu increase by 20psi? Not related to your fuel press issue, but your RPM and dwell looks horrible, I cant imagine the spark timing is very stable like that. What do you have for a trigger? Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 17 Author Report Share Posted April 17 Sure, here it is: https://drive.google.com/file/d/1mQtrxLFBgl6IUbwO945mr6Lz9PK1QaWj/view?usp=sharing I'll double-check this but pretty sure it does. Report back later. Yes, it's been mentioned a few times in this and other groups how bad it is. Not sure why. After speaking to Mark he kindly offered to lend me an NZ one to test but I think it's just better to upgrade to the NZ trigger kit either way. This CAS is 32 years old (with AEM disc) so has probably seen better days. After thinking about it overnight I was also under the impression that it probably won't fix my FP issue as this is mechanical rather than ECU-controlled but maybe I'm wrong..? Quote Link to comment Share on other sites More sharing options...
AbbeyMS Posted April 17 Report Share Posted April 17 57 minutes ago, Japtastic141 said: Sure, here it is: https://drive.google.com/file/d/1mQtrxLFBgl6IUbwO945mr6Lz9PK1QaWj/view?usp=sharing I'll double-check this but pretty sure it does. Report back later. Yes, it's been mentioned a few times in this and other groups how bad it is. Not sure why. After speaking to Mark he kindly offered to lend me an NZ one to test but I think it's just better to upgrade to the NZ trigger kit either way. This CAS is 32 years old (with AEM disc) so has probably seen better days. After thinking about it overnight I was also under the impression that it probably won't fix my FP issue as this is mechanical rather than ECU-controlled but maybe I'm wrong..? Adam , also the fuel pressure output isn't good either , MAP output is good thou. Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 17 Report Share Posted April 17 45 minutes ago, AbbeyMS said: Adam , also the fuel pressure output isn't good either Yeah two different problems, I can not imagine any scenario that would create a relationship between measured fuel press and erratic trigger teeth timing. @Japtastic141 What fuel pressure sensor do you have? It is unlikely that calibration you have in your map is correct. It is not linear, only has a 2.9V range and cant measure anything below 150kPa? I dont think anyone would make a pressure sensor that has no logical references like this. Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 17 Author Report Share Posted April 17 It's a GReddy one. The ECU reports the same as the in-car gauge. I didn't put the lower and higher values in yet. I know the calibration is not bang on perfect but it's pretty close. I'll work on this but still doesn't help or explain the massive fuel differential. Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 17 Author Report Share Posted April 17 The more I think about this the more it confuses me. I've learnt a lot over the last few months and am fairly sure I have a decent grip on what is supposed to happen with a 1:1 referenced FPR and all my tests while the car is on or off and stationary confirm that everything looks perfect. When used live it doesn't follow what I see stationary as you know from the logs. 3 Different Fuel Pumps - same issue 2 Different FPR's - same issue Return flow test at various pressure has always returned the correct amount and bang on what Walbro publish. Mytivac to FPR reference port - Perfect 1:1 pressure increase and decrease and holds it. Line to FPR tried on it's own port at the front of the balance tube and T'd into the MAP sensor line at the rear of the balance tube. New AWG4 wire to new relay for fuel pump and even bypassed relay and ECU control as a test. Picoscoped voltage and amps at the pump and all looks good. Surely this is now some kind of weird mechanical issue rather than ECU, config, wiring etc? It's like there is not enough pressure on the FPR reference line to hold open/closed the spring/diaphragm but there is enough to supply the MAP sensor and boost gauge with the correct figures. Does this theory make any sense at all and if so what are the likely culprits? On a slightly separate note, adjusted the calibration table. Should be bang on now. FP on the gauge and ECU match perfectly. On that theory and maybe not important at all but thought worth mentioning, I have noticed that my 'plumbing' is not factory for the vacuum lines. AC = Air Chamber BC = Mac 3 Port Green are rubber lines, black is hard lines. Quote Link to comment Share on other sites More sharing options...
0x33 Posted April 17 Report Share Posted April 17 Sorry if mentioned before, but what sensor are you using and where is it plumbed in? Seen similar behaviour on a cheapy sensor that was showing all sorts of weird behavior Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 18 Author Report Share Posted April 18 GReddy so should be quite decent. Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 18 Author Report Share Posted April 18 Spent some time today changing out the last two fuel hoses to the hat from the hard lines under the car and then putting the the cam belt cover on. This has cleaned up the RPM a fair bit. These logs are with no filtering applied. The CAS definitely likes those rubber gaskets for vibration it seems! I thought I'd do a test with boost reference removed from FPR and set to 400 kpa. Still dips by nearly 60 kpa. With no reference shouldn't the FPR keep the same pressure it's set to? This is it set back to normal 300kpa and boost reference back on. [url=https://ibb.co/80HsSK0][img]https://i.ibb.co/xDNLRCD/image.png[/img][/url] Quote Link to comment Share on other sites More sharing options...
David Ferguson Posted April 18 Report Share Posted April 18 All this seems to be leading to the manifold pressure reference going to the FPR is not really manifold pressure (i.e. it's restricted, leaking under boost, or similar). Or the Fuel Pressure Regulator isn't plumbed correctly, or has a leak itself. Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 18 Author Report Share Posted April 18 Well yes, that was a theory a couple of days ago but now seeing that fuel pressure drops without any boost reference attached makes me think again. I need to think it all over. Been a long day juggling work, family and car bits! Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 19 Report Share Posted April 19 All mechanical regulators have what is known as a pressure gradient or regulation slope. Pressure varies with flow and the pressure control is never perfectly 1:1 with the boost reference. The slope is typically around 0.25kPa/LPH but some are much worse than others. I think your last pic with the pressure dropping 60Kpa is more than just the regulation slope though, it looks more like a supply restriction or lack of pump. Quote Link to comment Share on other sites More sharing options...
Japtastic141 Posted April 19 Author Report Share Posted April 19 Thanks Adam, that’s the info I didn’t know about FPR’s. But if it looks abnormal and more than it should be I’m back to square one. The voltage dropping at the ECU so much and in conjunction with this happening does bother me and it’s the only thing now that I haven’t really spent a huge amount of time on. I feel like it needs sorting either way. I’ll do another run with the Picoscope attached to the pump to check Voltage and Current just to be sure nothing has changed there. Next, I’ll spend some time looking at the ECU voltage drop, as quite frankly there is nothing else I can think of to try or test… Quote Link to comment Share on other sites More sharing options...
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