hello all sorry if this was said before, my issue is a dying 2012 LR4 mainly on idle, after minute to minute and a half. starts right up like a champ, although, when i put the scanner on , i see fuel pressure drop from over 1000 to 0 when it dies, no engine light or anything, dealership diagnose is high pressure fuel pump, got them, replaced with new Bosch ones nothing changed, also replaced low pressure fuel pump and the filter ... same problem, replaced crank sensor, fuel pressure sensor, both PCV, alternator, smoged it and no leak or anything, you can drive the car for hours with no problem, if you stop at a light for like a min, then it will die when you take off, also it happenes only when the car is warm, first start in the morning left it running or over half an hour with no problem.
ANY HELP PLEASE

 

The only suggestion I can give with all of that is to clean the throttle body and MAFs...

The drop in fuel pressure could be cause of the RPM dip, which is too fast for the ECM to compensate for, therefore it dies?

I would get the money back from the dealership that replaced the parts.

Where are you located? If it's close to 53147 I'd gladly take a look.

 

Both got replaced, I forgot to mention that, both throttle body and both MAF

 

Need @abran to make an appearance

 

So, Throttle body was replaced?

I would check the throttle body electrical connector, sometimes the lock tab breaks and the connector comes loose.

If not that, I would suspect the actual gas pedal. It has an electronic sensor on it that sends a message to the throttle body.

 

swapped the gas paddle with another LR4 just to check , same problem , and the Donner vehicle is running fine with no problems
, can a high pressure fuel pumps has a timing issue , that only shows up on idle ???

 

I imagine you would get a code if that’s the case.

let me think about it, what’s @LR Techniker thinking on this one?

 

So, I ran this by another tech and he thinks it's the ECU shutting down the high pressure pumps.

Apparently in the diagnostics you can shut down one or the other pump to test the pumps function.

If you have the GAP tool I would try a software update or reinstall.

Good luck.

 

I'm out of town, so I apologize for a late half-baked reply.

If your fuel pressure is truly dropping to 0 psi, then you do not have a high pressure issue. why the dealer recommended two pumps is pure reckless shotgunning.

If the high pressure pumps were bad (even both of them), you would still maintain the pressure created by the low pressure pumps. The fact that it drops to 0 psi, means one of two things: You have a really bad leaking injector dumping all the fuel into the cylinder or the low pressure system is stopping fuel delivery.
I doubt you have a leaking injector because to be that bad, the engine would heavily misfiring, or even flooded or hydrolocked. Since that doesn't seem to be the case, then I would look at the low pressure system.

What I would do, is monitor pump voltage from the driver module. There is a fuel pump relay in the underhood fuse panel and a Fuel Pump Driver module in the left side of the cargo area. Any one of these can cause a drop of voltage to the low pressure pump and if the low pressure pump shuts down, the high pressure pumps have nothing to output.

You should be able to monitor the output of the Fuel Pump relay by checking for voltage on Fuse 1 (25A) at the underhood fuse panel. That fuse is on the ouput side of hte relay and feeds power to the Driver Module. By seeing where you do and don't have power during the stall, you can narrow down where the fault it.

 

Just remembered, I rigged up a kill switch for a customers 5.0 sport that plugged into the fuel pump relay slot. Even with the fuel pump turned off the car would run, badly mind you, but it seems like the high pressure pumps were pulling enough fuel to make it run.