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Rb25Neo Ecu Help!

amnash

By amnash,
in Engines & Forced Induction

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amnash Enthusiast

amnash

Posted
Posted

so last summer i was having an issue with my fuel pump not priming and i had to just reselect the key to "on" a couple times and it would kick on and fire up. well at the end of the summer it was getting worse and worse and now it wont turn on the pump at all. The fuel pump relay is FINE.

If i ground the ecu signal wire at the relay the relay clicks and pump turns on (the car wont run this way though. ecu doesnt want to give spark like this). The ecu is not sending the signal anymore. loose wire maybe? nope. here's the weird part, checking continuity between signal wire and ground, with ignition to "off" i have closed circuit and when i select ignition to "on" the circuit opens. so the ecu is basically doing the opposite of what it is supposed to do. im skeptical that it is anything to do with the wiring, i did the harness conversion myself soldered/heat shrink all connections. Not to mention i drove it for a year and a half probably about 7000km including a trip down to the states with no issues at all.

i think something is loose within the ecu, every signal being sent from ecu is intermittent and sporadic. the nissan datascan will only connect sometimes, before when it wasn't so bad i could connect nissan datascan use that to turn the pump on then start the engine. now when ever i do manage to connect and turn the pump off it will fire up for a second then shut off and loose connection with datascan.

i took the ecu apart and had a look, nothing looks melted or anything. gave the larger grounding points a light sand and added a good grounding wire to case ground it. no change. also with ignition in "on" if i move around the ecu the pump will sporadically turn on almost like a flutter its so fast.. any ideas?????? what are my options?

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https://www.sau.com.au/forums/topic/434689-rb25neo-ecu-help/
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StevenCJR31 Veteran

StevenCJR31

Posted
Posted

If you can move the ecu around and the pump kicks in/ out then its a problem with your wiring harness or plug at the ecu end

Is the harness plugged in nicely or is it overtightened and has a bend in it?

BlindspottNZ Explorer

BlindspottNZ

Posted
Posted

have you ruled out battery issues?

It sounds like a short somewhere, can you run a new wire just for test purposes between possible problem terminals? I once had a car where a wire had been damaged and was cut through the insulation/frayed where it passed through the firewall... (turned out it was the positive to the coils... :rolleyes: ) it was earthing out on the firewall itself.

amnash Enthusiast

amnash

Posted
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Posted

If you can move the ecu around and the pump kicks in/ out then its a problem with your wiring harness or plug at the ecu end

Is the harness plugged in nicely or is it overtightened and has a bend in it?

yea i didnt over tighten the bolt. just until it bottemed out. but yea, theres definately a slight bend in the connection thats for sure. the center sits in deeper then the ends of the plug.. how would i fix this??

GTSBoy Grand Master

GTSBoy

Posted
Posted

If there is any curvature in the ECU plug at all you could be in for a world of trouble with pins not contacting properly. It may have been abused in the past. Take the plug off and inspect each and every pin to ensure that they are all fully inserted into the back of the plug and latched in. Then take a look at the curvature of the plug and if there is a mm or more of bend in it consider getting another one from a wreck's loom and swap over. Check the ECU's socket pins too to make sure it's all kosher in there. A little twist or bend can prevent the plug from wanting to pull in. And when you assemble, use a great deal of mech sympathy. Don't just use the bolt to pull it in. Make sure you can assist/wiggle the plug in with your hand at the start and several times during the bolt up.

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