jryan Posted April 20, 2021 Report Share Posted April 20, 2021 Hello, I have 2002 WRX (US), with a stock 2013 WRX motor, Link G4+ PnP ecu, ID 1000 injectors, Walbro 450 pump, the positive side of my pump is hardwired via a relay and the negative still goes through the oem fuel pump controller (but with increased ground wire size), aeromotive adjustable fuel pressure regulator and a load of other possibly unrelated mods. Things appear to run fine on a flashed oem ECU (I assume that it was successfully backing off to 33 and 66% DC, but never directly verified it). When I try to run the same set up on my link ecu, it primes fine, starts up easily enough, then runs okay at high idle but as soon as it tries to settle down to a reasonable idle rpm (and supposedly down to either 33% or 66% duty cycle) the fuel pressure falls off to zero and the car stalls. If I tried a new OEM fuel pump controller, same results. Before I reluctantly give up and rewire things without the oem controller, is there anything that I'm doing wrong on the tune that could cause anything like this? Or any ideas what could cause this? Thanks in advance. * The attached tune is probably pretty far from good in general as I haven't been able to have it run long enough to do much yet and I tried changing random things to try to get it to idle before noticing the fuel pressure drop off and messed with the pressure regulator more than I should have after trying to figure this out. ColdStartFuelPressureDrop.llg V7WRXV10MotorID1000.pclr Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 20, 2021 Report Share Posted April 20, 2021 It would appear your pump is not happy at 33% (note that is only the DC that the FPC gets, Im not sure if it actually outputs the same 33% DC to the pump or if the relationship is not 1:1). You could try something like below so it switches to higher DC earlier (I still think idle will be less than 3% inj DC though so this may not help), or you can just set Aux 7 to off and the pump will run full speed all the time. Another option would be to use the openloop pump control option and just switch between 66% at idle and 100% a bit higher up if you wanted more flexability. Quote Link to comment Share on other sites More sharing options...
jryan Posted April 20, 2021 Author Report Share Posted April 20, 2021 I tried setting FP Low -> Med %3 and FP Med -> High to %5, but got the same results. I just tried changing Aux 7 from "FP Speed" to "Off" and the pump didn't even prime, should that for sure work or is that a clue? Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 20, 2021 Report Share Posted April 20, 2021 Oh, I just found a trick I missed. You need to set the polarity to low on aux 7 before turning it off - then it should run at 100% all the time. Quote Link to comment Share on other sites More sharing options...
jryan Posted April 21, 2021 Author Report Share Posted April 21, 2021 That worked (are there any other known useful disabled options that still have impact hacks). On the plus side, I'm able to start tuning, on the down side my walbro 450 at 100% drains my little race car battery pretty quickly, was down quite a bit even in the time it takes to store to the ECU, good thing I wired in a fuel pump kill switch way back when... Long term, I probably need to figure something better out. Either figure out why this setup wasn't working or do the infamous jag controller setup. Thanks! Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 21, 2021 Report Share Posted April 21, 2021 On 4/20/2021 at 4:13 PM, Adamw said: Another option would be to use the openloop pump control option and just switch between 66% at idle and 100% a bit higher up if you wanted more flexability. Quote Link to comment Share on other sites More sharing options...
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