Yowzer Posted November 12, 2017 Share Posted November 12, 2017 Check the pulldown resistors on the injector FETs. Is the hardware configured as per factory spec or has it been altered? Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted November 12, 2017 Share Posted November 12, 2017 all I found online so far was that to make sure the injectors are getting switched 12v which I will confirm, I just used the factory injector wiring so it might be wrong. The engine runs fine and the injectors close up when I turn the ecu on (not even running) cause I see the small rise in fuel pressure. It's just when the ecu is shut off that they open up, which does sound like when the ecu turns off it pulls to earth on the injector pins and causes this issue Quote Link to comment Share on other sites More sharing options...
ajg193 Posted November 12, 2017 Share Posted November 12, 2017 So with your fuel pump connected directly to the ECU output does it also come on whenever there is 12 V to the ECU? Are you running your injectors from the same relay as the pump? Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted November 12, 2017 Share Posted November 12, 2017 actually thats a sympton i forgot to mention and actually forgot i had. the fuel pump runs with the ecu turned off aswell (and thats how i filled the bores with fuel!!), and when i turn the key to on it primed for a few seconds and then switches off. Quote Link to comment Share on other sites More sharing options...
ajg193 Posted November 12, 2017 Share Posted November 12, 2017 Why's your ECU (or the fuel pump relay) getting power with the key switched off? You should have a second relay that comes on to power the ECU. For mine I just trigger the relay using the carb idle valve power supply wire. Do you have a back of a napkin diagram of your wiring? Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted November 12, 2017 Share Posted November 12, 2017 there is an ecu relay, but its looking like when the ecu shuts off that it pulls some pins to ground which is grounding out some of other relays. the fuel pump replay is 12v powered on both sides and pulled to earth to switch the pump as per the MS wiring diagram. its possible that its not ecu related and just back feeding through something, though my radiator fan doesnt act this way. edit after posting this i noticed that the fuel pump relay should be off the main relay, this could be an issue, however i dont believe i had it wired this way when i was running it on my old setup. Quote Link to comment Share on other sites More sharing options...
ajg193 Posted November 12, 2017 Share Posted November 12, 2017 I don't think that will be an issue with the key wiring to the fuel pump relay. I don't do that with my microsquirt and have no issues (I probably should do it for safety though) Measure the resistance of pin37 to ground when the key is off, should be huge resistance.* If it is nonzero but not huge then it is likely the pull down resistor on the fuel pump transistor is bad. /I really don't know what I'm talking about/what else it could be. *Assuming the system works the same way as MS2/Microsquirt Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted November 12, 2017 Share Posted November 12, 2017 its probably not much different in architecture. ill take a look at the injector wiring and double check the fuel pump wiring, im 90% sure itll be that the old ecu ran the injectors slightly diifferently and i just need to chuch a relay in the mix. at the very least itll probably bandaid fix the problem and ill be non the wiser.. Quote Link to comment Share on other sites More sharing options...
Testament Posted November 12, 2017 Share Posted November 12, 2017 it sounds like you have the fuel pump (and injector) relay switched off the key and not of the ecu as it should be (as shown in the diagram), or alternatively the relay has failed in the switched on position. in either case you should really sort that. when its wired up correctly you key on and the ecu should power up and it will run the fuel pump for a second or so to prime the fuel rail then switch off. but for the injector issue as alluded to there must be some path you ground on the negative side wiring of the injectors - for them to open there is power getting to them (from your relay issue) AND that power getting back to ground via some path which it shouldn't be. when its operating correctly the ground goes through the ecu and that is what it switches to control your injection. maybe have a look at how the resistors are mounted and thigns like that - its probably not a strong ground leak as if it was the injectors would be just 100% open and the car wouldn't run. Quote Link to comment Share on other sites More sharing options...
ajg193 Posted November 12, 2017 Share Posted November 12, 2017 6 minutes ago, Testament said: it sounds like you have the fuel pump (and injector) relay switched off the key and not of the ecu as it should be (as shown in the diagram), or alternatively the relay has failed in the switched on position. in either case you should really sort that. when its wired up correctly you key on and the ecu should power up and it will run the fuel pump for a second or so to prime the fuel rail then switch off. but for the injector issue as alluded to there must be some path you ground on the negative side wiring of the injectors - for them to open there is power getting to them (from your relay issue) AND that power getting back to ground via some path which it shouldn't be. when its operating correctly the ground goes through the ecu and that is what it switches to control your injection. maybe have a look at how the resistors are mounted and thigns like that - its probably not a strong ground leak as if it was the injectors would be just 100% open and the car wouldn't run. 13 hours ago, BlownCorona said: the fuel pump runs with the ecu turned off aswell (and thats how i filled the bores with fuel!!), and when i turn the key to on it primed for a few seconds and then switches off. Would indicate not an issue with the injector grounds/kinked wire somewhere nor a relay stuck closed as fuel pump uses separate ground to injectors and suffers same issue. By wiring key feed into the injector/pump relay positive signal line then you should be able to solve the issue, but it doesn't seem like it will really solve the underlying problem, just mask it Quote Link to comment Share on other sites More sharing options...
mjrstar Posted November 12, 2017 Share Posted November 12, 2017 Had a similar issue with my link, using just the pull to ground for the fuel pump relay would leave some form of earth loop through the ecu when powered down. This is a common occurrence. Adding a +ve switched feed from the ign on position fixed it. Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted November 13, 2017 Share Posted November 13, 2017 im not running the car or even powering it up properly untill its sorted. but i agree that switched power feeds are probably the problem, im also gonna find a nice relay/fuse box as itll help tidy up one of the most messy areas i have in the bay. any recommendations? Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted November 13, 2017 Share Posted November 13, 2017 i can confirm the injectors get straight battery power. im picking the 18rgeu ecu doesnt ground out the injector pins when it shuts off. should be a simple fix, whether or not the megasquirt is supposed to ground the injecor pins when its off im not sure but will endevour to find out. from what i can gather its possibly normal 1 Quote Link to comment Share on other sites More sharing options...
NickJ Posted November 13, 2017 Share Posted November 13, 2017 Drew up the first manifold concept tonight, few things line up better than I thought, but there is one bolt that clashes, I have a few ideas there, but ultimately I think a stud will sort it out. Need to have a second measure up of the head and engine bay that all will fit, then all that holds it back is a chat with the waterjet guys to agree with the madness and i'll get some cutting underway! 3 Quote Link to comment Share on other sites More sharing options...
peteretep Posted November 14, 2017 Share Posted November 14, 2017 that looks expensive 1 Quote Link to comment Share on other sites More sharing options...
ajg193 Posted November 14, 2017 Share Posted November 14, 2017 23 hours ago, NickJ said: Drew up the first manifold concept tonight, few things line up better than I thought, but there is one bolt that clashes, I have a few ideas there, but ultimately I think a stud will sort it out. Need to have a second measure up of the head and engine bay that all will fit, then all that holds it back is a chat with the waterjet guys to agree with the madness and i'll get some cutting underway! Differential heating and warping not going to be an issue with that? Could be a great opportunity to play with casting Quote Link to comment Share on other sites More sharing options...
NickJ Posted November 14, 2017 Share Posted November 14, 2017 13 minutes ago, ajg193 said: Differential heating and warping not going to be an issue with that? Could be a great opportunity to play with casting Crossflow head, all aluminium, no worse than standard 18 minutes ago, peteretep said: that looks expensive Only doing it this way as we have all the ingredients on the shelf! Quote Link to comment Share on other sites More sharing options...
downtrail Posted November 14, 2017 Share Posted November 14, 2017 On 13/11/2017 at 16:42, BlownCorona said: i can confirm the injectors get straight battery power. im picking the 18rgeu ecu doesnt ground out the injector pins when it shuts off. should be a simple fix, whether or not the megasquirt is supposed to ground the injecor pins when its off im not sure but will endevour to find out. from what i can gather its possibly normal Yes the feed ro injectors need to be switched with ignition. If they have const bat voltage it will back feed the ecu through the flyback circuit and cause weird stuff to happen. Just put a relay in the 12v feed to injectors and switch it with ignition. Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted November 15, 2017 Share Posted November 15, 2017 Will do this weekend! Also have to change the oil incase fuel made its way past the bores but I'm keen to see how it starts once it hasn't emptied the fuel rail into the bores on shut down! Certainly explains alot of stuff that I was trying to tune out to no avail. @downtrail while your here (and anyone else that might know) , do you know of any nice small relay and fuse boxes, I'm after something to hold atleast 4 relays plus fuses and will allow me to tuck all the wiring away as right now it looks very ugly 1 Quote Link to comment Share on other sites More sharing options...
ajg193 Posted November 15, 2017 Share Posted November 15, 2017 I too am interested in some sort of fuse/relay box. Been thinking about going to pick a part to get something but not sure if that would be ideal Quote Link to comment Share on other sites More sharing options...
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