I need a 2jz wiring guru please. Wot classic sees 11.59v at 7200rpm. Battery post in trunk sees 13.75, changed battery, tested alternator, both good. Running a hellcat 525lph pump off a relay if that makes a difference. 12v power connector has 2 wires, grey and black/orange. I can’t trace these to engine bay. Seems to only dip around 7200 the goes back to 12.35. Any help appreciated
black or classic?
what chassis? how’s it wired in?
Post tune and datalog
Classic on a supra. I can try post the log but it was my tuner who found it dropped and always at same rpm range and then leans out the fuel.
I’ll try post the tune from the pc
mk3 supra? mk4 supra? GE or GTE?
is it using a plug and play adapter or wired in?
The battery sees this voltage drop or the ecu only?
if this is repeatable then could be the alternator or a ground offset issue. I don’t have enough info yet to answer with anything more then a guess
I thonknthat will be grouding issue if i remeber correctly oem ecu grounds are connected tonthe chassis
Thanks Tyson sorry for the lack of info. Supra mk4 na-t Lexus engine. Things tried.
4awg earths alt to chassis, block to chassis head to chassis, intake runners to chassis. Ecu earths 0.3-0.5ohm all secure. Battery voltage in trunk 13.75v at 7200 rpm. Alternator tested by rebuilder to be working perfect. All connections cleaned up. So when Ecu was seeing 11.95v at 7200rpm, battery was seeing 13.75 tested with fluke multimeter. Fuel pump wired to a relay since installation so getting its own power.
Today I’ve installed a 4 pin relay. 12v post from fusebox to relay 30, earth straight from head to 85, ecu fused 30a to ecu classic pin 18 from 87 and then cut the grey wire plus black and orange wire from main relay that originally went to 18 and connected it to 86 on the relay. I’m hoping I’ve done this right but I’m sure I have. Just need to test it now. Any input appreciated. I’ve also changed this fuse that was on the main relay circuit as the original blew last year and this thin looking one was installed. Wonder if that could’ve been the bottle neck
So installed the relay, voltage is nice and solid with no downward spikes steady at 13.5 minimum at 4000 but now it feels like I have a slight misfire. Could I have disturbed a coil wire? I have a log to send if anyone wants to check
thank you,
ok so a 1.8V difference between ECU and battery is pretty substantial.
Relay from battery or main fuse box is a good idea, eliminates potential issues with oem wiring.
The ecu should be grounded to the head, or the intake manifold where the rest of the ignition system and OEM ecu ground to.
‘All connections cleaned up’ assuming that means they are tight, paint free and free of corrosion?
I have had fuses add resistance, but it’s been very rare.
Testing the ecu grounds via an Ohmmeter only really tells you that they are connected. You need to do a voltage drop test under load to really learn anything. Load would be highest when the injectors pulsewidth is largest and potentially ignition coils dwell is high
What is the ignition coil situation? lexus engine makes me think its a wastespark three coil pack type. is there still an igniter?
Post the log, and the tune file so we can take a look.