Rav4.2 D4D Loss of fuel pressure on acceleration

December 28, 2018

Hi,

As above, I've been noticing that sometimes on acceleration the engine goes "flat" for a few seconds, before suddenly kicking into action. I suspected a loss of fuel pressure so I removed the SCV valves and cleaned them thoroughly using carb cleaner and an ultrasonic bath, using a Battery to actuate them continuously throughout both cleaning procedures. Both valves had approx 1.7 Ohms resistance across the terminals which is in spec. Both seemed to behave as expected.

I reinserted them, added a cleaning additive to my fuel tank, and went for a test drive with the laptop logging common rail pressure vs throttle position. Graph is below.

When the throttle is pressed causing a sudden increase in demand, the common rail pressure is tanking. It stays low for a few seconds, then suddenly shoots up and the car pulls away. Does anyone know what might be causing this? This is after the mentioned cleaning procedure on the SCV valves.

A gradual increase in throttle doesn't seem to have the same issues, and the issue doesn't happen every single time. Maybe 80% of the time.

Before this the car has been off the road for a couple of months awaiting repairs. There were no issues like this that I remember before the period off road. Included in the repairs was a throttle position sensor, so that isn't at fault (plus output can be seen on the graph).

A full service including fuel filter was done about 3,000 miles ago. The timing belt was replaced along with the clutch and flywheel during the off road period, and the turbo was new 5,000 miles ago.

I initially suspected fuel pressure based on the instant power kick in, and the period of non use (plus the temperature changing form 30C to 5C).

I've searched online but I didn't find anything about this specifically. Has anyone encountered something like this before? Is it worth just running a tank of premium diesel plus additive through it and seeing if that clears up the issue?

Thanks for any help anyone can offer!