Hi all,
Standard apology first - I've lurked on here but as a relatively new Lexus owner from over the pond, not got round to signing up until today! So yes, my first post is a plea for help, on something which seems like a pretty uncommon problem...

My car: 2010 GS450h (but I don't think this is a 'hybrid problem' so please keep reading!).

The problem: Over the weekend I noticed a 'hiccup' (momentary loss of power, no fault codes) twice (on two different days), but then the car ran fine afterwards. Yesterday however, the dreaded engine warning light appeared on my way to work - code p0087. Didn't find much out through a quick google in the day, but when I set off to get home it transpired that all was definitely not well. It was a bit hesitant in the beginning but very quickly (within a couple of miles) got worse, to the point where it now it runs fine as long as you don't give it more than a tiny bit of throttle - if you do, it cuts out completely and reverts to battery power until restarted. If driven very gently, it switches between engine and electric power just fine. I tried clearing the code (shown as 'pending' btw) but it comes straight back and there's no change to the symptoms. I got the car home ok (not on the motorway though!), but now I'm stuck with what to do!

Everything is pointing at this being a fuel issue and nothing to do with the hybrid system. The fuel setup is (I believe) very similar to that on any number of 6-cyl GS/ISs, but I've not seen much mention of this problem anywhere.

The potential faults as I see them:

• High pressure fuel pump - would it run at all if this had failed? Would I expect to see any other fault codes?
• Low pressure fuel pump - same questions as for the HP pump! I can command it to run in techstream and it seems ok from there, but that's a pretty limited test.
• Fuel pressure regulator/piping/filter - I don't even know what the setup looks like but I guess it feels more like something has 'stopped' from an electrical point of view rather than a leak/blockage?
• Fuel rail pressure sensor - the only reference I've found to these failing sees other fault codes thrown too...

Anyone else got any genius ideas, or seen something similar??

 

Looking at the freeze frame data in techstream against the fault code - can anyone sanity-check my logic?

Fuel pressure (kPag)
-3: 180
-2: 180
-1: 100
0: 180
1: 200

Fuel pressure target value (MPa)
-3: 6.22
-2: 9.54
-1: 12.00
0: 10.59
1: 6.75

Given that MPa= kPag x 1000, these two say to me that it certainly isn't making (seeing?) as much fuel pressure as it wants!

HP FP discharge rate:
-3: 280
-2: 280
-1: 280
0: 280
1: 0

Is that it turning the high pressure pump off as the code is set?

Injection way:
-3: Direct
-2: Either
-1: Either
0: Either
1: Direct

I don't know what the terminology is here! Anyone shed any light?

 

So who knows anything about what I should expect to see in the way of fuel pressure?

According to techstream, "Fuel Press" (kPag) is <200 when running, but when the engine (and fuel pump) shut itself off (after the hybrid battery charged sufficiently), the value started gradually climbing. It went as far as 5200 after about 6 minutes, then started dropping again...

Is this increase normal, explained by e.g. heat soak into the now-stationary fuel at the rail, or is it potentially a sign that the sensor is playing up?

What should fuel pressure be with the engine running? Anyone else who could take a look at what their car (any 6-cyl GS/IS I guess) would be a hero!

 

Have you checked your fuel cap?

 

I've checked that it's fitted properly, but not that it functions as such... It does hold pressure, as you can hear it releasing when removed. Is there something else I can do?
Thanks btw!

 

Fuel system diagram here:
https://toyota-club.net/files/faq/13...engine_eng.htm

You can force your car to idle in two ways:
1) Hold brake pedal, S-mode on the transmission, hit the throttle just so that the engine starts running, then release (keep holding the brakes).
2) Maintenance mode - same as Prius and just about any other hybrid. Ignition ON (double press "on" button without holding pedals), double fully press and release throttle, shift to neutral, same thing, shift back to park, same thing, "maintenance mode" should appear on the dashboard's LCD. Traction and stability controls are OFF. Read up on why these can't easily be disabled on hybrids. Keywords - "Back EMF", sparks across the IGBTs on the inverter. I wouldn't risk it, even though RHD inverters (is your location right? :P ) seem to be quite plentiful

Regarding the fuel pressure sensor, from a 3GR-FSE manual (currently don't have access to a 2GR-FSE one):
"Check that the fuel pressure fluctuates when the engine condition changes from idling to racing. "

Doesn't fluctuate - replace sensor.
Fluctuates - check high fuel pressure components.
"Fuel pressure does not rise" (so I guess "doesn't fluctuate" = stays static or something) - check fuel pump & the other low fuel pressure lines.

Now, more general:

Description of the 3GR-FSE fuel system:
p0087:
techinfo.toyota.com & lexus-tech.eu - the US techinfo is cheaper. I highly suggest that you take a look, even though it is paid.

I'll go play with the car for a bit, expect charts soon

edit:



Engine is warm-ish (70+ coolant temp) from the get-go. First one is cruising on EV and then running the engine (sports mode to hold it running and to vary the RPM, flooring it to vary the load), then stopping for a bit to let the.. ehh... ambient FP raise. Second one is a bit after that - forced it to idle (brakes + sports), then it started force-charging. Force-idle fluctuates around 4M +-200K, force-charge is around 6M.

EDIT: Injection way - it's "direct" (in cylinder), "port" (in manifold, i.e. behind the valves, standard MPI), "either" (combination of both, the way the engine works most of the time).
Take a look at the attachment of this post:
https://www.clublexus.com/forums/is-...ml#post9111558

 

The 2006-2008 gs450h was recalled for fuel system issues so you might check and see if the 2010 was as well.