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lost coms

Mason Lockyer

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Hi there got rb25 going good nice base tune been good all week owner real happy and getting ready for dyno next week. Owner popped in tonight(friday) with car for a chat and a mate of his turned up too and asked to go for a drive. problems starts here he cranks engine and no go i have a look no fuel pressure. Check power feeds to ecu/injectors/coils/ignitor pack which is all good. Found ecu not earthing fuel pump relay out and earthing fan relay all the time and fan staying so i plug laptop in and no coms with link and also laptop slows down unplug usb cable and laptop speeds up. At one stage it managed to connect a message came up on screen ecu gone to shut down mode or something like that and reset needed. Any ideas please

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I have seen things like this happen before when the ECU has power supply or ground problems.  Make sure the ECCS relay is on and that the ECCS fuse has not blown.  If the ECU does not have 12V at its 12V pin it can not power up correctly.  If there is some sort of backfeeding going on due to some sort of power supply problem, the ECU may be powering up only with not enough voltgae to correctly run.  That is often why funny things happen with outputs (like the fan coming on).  Of course the ECU can not communicate with the PC when the ECU is in a half powered state...

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