View Full Version : RB20DET Running extremely lean on idle.

08-24-2019, 10:45 PM
Hey everyone. So to start, my RB20DET ran fine in my other chassis, when i swapped it to my new chassis and switched to a front mount the car runs extremely lean on idle. AEM Wideband is reading 16-17 and then so lean it wont even give me a reading. I havent found any leaks in my couplers or IC piping and cant seem to narrow down if there is a vac leak. I replaced the plugs/coil packs already but cant figure out what my issue is. Stock RB20 with an RB25NEO turbo and ISR downpipe/exhaust.

Any ideas on what else to trouble shoot? Fuel pump finally shit the bed maybe?

08-25-2019, 09:48 PM
Either the FP or FPR have gone to shit. Unless the fuel line is plugged or filter is bad. Check to see it the hard lines are pinched from something.

Have a great day,

08-25-2019, 11:35 PM
Vac leak more than likely. Past your TB if its lean. Basically between your tb and pistons. Do a proper leak test, probably something you forgot or a loose clamp or a missing plug. Happens all the time during swaps.