So, i swapped out the injectors on my LR3 and have had rich codes thrown (both banks) and rough running since. (4.4L V8)

I'm thinking the fuel rail pressure sensor is going out on me?

Live values at idle from GAP tool:

Fuel rail pressure = 513.7 kPA (converts to 74 psi which is high, pretty sure it should be 65 psi)
Fuel rail pressure sensor voltage = 0

Only thing I can think of is the injectors weren't the right ones even though the part number checked out? The old ones were stamped 4280, and the replacements were 4260.

Also thinking its the rail pressure sensor? The 0v reading doesn't sound right to me.

 

We have fuel rail pressure sensor on the 4.4 V8?

Did you reset adaptions?

 

Yup, unless I'm mistaken (entirely possible) it's on the end of the passenger side rail (gray clip).

Yup, reset the adaptions, cleaned the MAF, throttle body and egr. Got new plugs to throw in and see if that does it.

Normally I'd figure it's a dying MAF or coil pack, but the live pressure reading threw me off.

 

I too could be wrong, but I think that is the fuel temperature sensor. Also no coil packs on the 4.4, just coils. A coil pack uses spark plug wires and is mounted on the engine.

 

Ah, makes sense.

All signs point to the fuel pump then.

 

I kinda doubt the fuel pump would be the issue. Certainly not on its own at least. The pressure regulator is located inside the tank and separate from the pump itself. If a fuel pump goes bad, it generally causes low pressure and thus a lean condition. If you are truly thinking pump, you could get a mechanical (actual) pressure reading from it. Only the early LR3s had valves on the rail, unfortunately. So I used a donor vehicle for a fuel line from tank to engine bay and attached a gauge to it. Then I plugged it into the fuel outlet at the front of the tank. Really easy to get to. Then I was able to get reliable fuel pressure readings.

 

I am not really familiar with injectors - never had to change any before.
But maybe 4280 and 4260 have different flow rates?

Can you confirm the Part Number you bought, and from where?

 

Yes, it seems to me you that if the problem appeared only after you changed a part (the injectors), then most likely the problem is in those new parts, not somewhere else.
The first check I'd do is to put the old injectors back in, and see if the rich codes go away. If the old ones aren't salvageable for some reason, then I'd put in a different, matched set from an injector refurber.
74 psi seems fine to me for fuel pressure.

 

Yeah, that's the path I'm gonna try.

That's what I just put in, a set of refurbed ones. I'm genuinely curious if the number on the electrical plug ends up mattering. The new ones are 2W93-AA same as the old. I picked up another set of refurbed ones stamped with the 4280, will swap em out in a day or so when they arrive. Unfortunately the old ones are a no go. 2 are cracked and leaking, which was what kicked all this fun off.

One good thing in all this is i can get the fuel rail off and back on in under 30 minutes now, haha

 

Update

2nd set of injectors came in today, made sure they were stamped '4280' on the electrical plug stem. Swapped them in, cleared adaptions and it runs smooth and error free.

As it turns out the number on the electrical stem of the injector does matter, even though they're all 2W93-AA.

In case anyone comes across this issue in the future, make sure the injectors you buy have 4280 on the electrical plug, even though other ones say they work for the LR3 with the 4.4 they do not.

Denso part # you want is 195500-4280
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