hey guys just wondering if anyone has experienced something similar, start car, engine races up to 2000rpm and sits there for about 10-15 sec accompanied by an intermittent buzzing sound from the rear/underneath of the car. idle then settles at normal rpm for a while and buzzing sounds go away. fluctuates randomly back up to 2000rpm accompanied by the buzzing sounds again. TPS has be adjusted and checked twice and is good, and Iv'e pulled out the FPCU and inspected the board and solder on the pins and cant see anything wrong. Is there some sort of test i can do on the FPCU? With the buzzing sound i'm assuming it's the fuel pump, it's really loud underneath the car but when im above the fuel pump inside the car with all the panels off i can hardly hear it? any help would be appreciated.
There's info on how to do this in the tech section, link in the menu bar near the top left of the page.
bypassed FPCU, idling perfect, seemed good whilst test driving, until i got back home then was stuck idling at 2000rpm, hesitating and blowing black smoke when reving. thinking fuel pressure reg maybe now?
You really need to test before replacing... You can check fuel pressure reg using an inline fuel pressure gauge. For what it's worth I would check coolant temperature sensor operation considering you have high idle and symptoms of running rich.
High idle could be massive boost leak aswell . Can you control the idle with the screw on the idle unit ?
didnt change pressure reg, pretty obvious there was nothing wrong with it, coolant temp sensor was working fine. Checked IACV, found a massively corroded plug, cleaned it up and went for a test drive, so far so good. ill see how she goes over the next few days.
Vague question..... ....deserves a vague answer. Maybe? You neglected to mention how much of a pressure variation the gauge is indicating. The FPCU adjusts voltage supplied to the fuel pump. Depending on circumstances, the fuel pump will be supplied with either battery voltage, or in the case of a TT, down to 6VDC, or with an NA, down to 8VDC. To verify what the voltage should be, refer to the Nissan FSM. In order to determine if the pressure fluctuations are related to the FPCU, you need to measure the voltage supplied to the pump.
Certainly will most either work or flat out die leaving you with no fuel at all ?! All aftermarket pumps require 12v minimum these days so running them with less than proper voltage can actually be a downgrade!
