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Been Chacing a issue for a couple weeks now, my rb20det starts and idles no problem, but hasn't been able to rev past 3k after doing a few upgrades, 1000cc Bosch injectors, arp headstuds, 25 box, e85 non flex, 2 stage boost controller, and a few small others.

Anyways, ecu is cutting out at 3k rpm, all signs pointed to afm (had a ebay z32 on it) checked the signal wire to ecu, not sending enough volts, tried a stock rb20det and rb25s2 afm, both wouldnt let the car start at all. Bought a z32 for it and wired it up, turned ignition to on position, afm was sending correct volts to ecu, turned key on and it started and idled fine, checked signal, correct voltage. Just before I could see if it would rev past 3k, it cut out. Now my earthing situation is gone weird, afm is getting voltage, both signal and 12v power grounds will only ground with the ignition on first click, second click it looses the earth, signal wire is sending nothing to ecu. Tried wiring the old afm back up, which It use to start and idle fine with, and it won't run and having the same wiring issues. Anyone have any input? I've pulled out the ecu to open up to see if I've burned something, haven't had a chance yet tho. Any input appreciated, thanks

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https://www.sau.com.au/forums/topic/470807-rb20-afm-earthing-issue/
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Stock ECU?

That will be alot of your problem if you are putting different AFM's in the car. The ECU is not designed to run anything but the AFM it came with unless you change the ECU

Also, how are you testing the voltages? Using a multi meter the wrong way can sometimes give the opposite results to what is expected. I'm not trying to be mean, just have to ask these questions. I'm still convinced that if you are on a stock ECU your problem is the non-stock AFM though

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