2011 LR4 Restricted Performance Mode

[jastutte]

my wife was driving the LR4 today when it went into Restricted Performance Mode. she made it to a parking lot where i met here and checked a few fuses and tested the battery. everything looked good there. my Foxwell NT had some issues communicating with the ecu/bcm, so never was able to pull the codes.

however, after restarting the vehicle, it ran fine and was back in its normal mode. i drove it for 20 minutes and no issues.

some quick reading suggest MAFs and/or fuel pumps. at 142,000 miles i can see it being either or both.

aside from getting a code reader that can communicate with the LR4 better, what else should i be looking at? should i do the MAFs as preventative maintenance? fuel pumps?

 

[MM3846]

I had a dirty MAF cause a restricted performance condition. Had to clean it 2-3 times but I eventually cleared the code. Get new air filters, too.

 

[jastutte]

thanks. i'll start with cleaning the MAFs and install new air filters.

 

[discostew]

Start by pulling codes. It stored a code in something if it went into restricted performance.

 

[discostew]

thanks. i'll start with cleaning the MAFs and install new air filters.

Don't clean mass air flow sensors. They fail soon after.

 

[jastutte]

Don't clean mass air flow sensors. They fail soon after.

shit.

 

[discostew]

I know people do that all the time. But engineering figured out the thing would actually really fail later. Maybe your alright. If you don't know better when you do it you have a chance. Now that you know better be careful.
Theres only a small handfull of things that will cause the restricted peformance message. Chase the codes.

 

[MM3846]

1.5 years and 15k miles later my MAF codes haven’t returned.

 

[jastutte]

after cleaning the MAFs it seems that acceleration is smoother. previously there was a little pause before the LR4 would jump forward.

 

[jastutte]

the LR4 went into restricted performance mode again last Thursday. turned off the Rover and let it sit for 10 minutes and the restricted performance warning was gone and LR4 drove normally. Friday the check engine light came on but no restricted performance warning. Saturday i plugged in the code reader. again, couldn't read the codes when using the LR specific software on my Foxwell NT 510. backed out to the generic OBD2 software and pulled up an MAF bank A code. cleared the code and drove the 80 miles back home with no issues today.

i am planning on replacing both MAFs and both air filters. i'd like to save bank B's MAF as a backup, assuming it is still good. anything to check before pulling the trigger?

oh, and, discostew, i guess you were right. you might have future in Land Rover diagnosis and repair.

 

[jastutte]

replaced both MAFs and air filters today. started the LR4 up and it had a very rough idle that shook the whole vehicle. of course, restricted performance popped up as did the check engine symbol. pulled out the generic (not rover specific) code reader and got two throttle position sensor codes. i think they were P2101 and P2135. like an idiot, i didn't take a photo of the code reader before erasing them. the codes went away, the restricted performance mode did not.

after erasing the codes, i let the LR4 sit for 10-15 minutes for the restricted performance mode to put itself to sleep. i pulled both new MAFs and installed the old ones. restarted the Rover and it idled fine, no codes, no restricted performance. so, i decided to play the elimination game. first i pulled the passenger side old MAF and installed the new one in its place. restarted the Rover and it idled fine, no codes, no restricted performance. then i pulled the driver's side old MAF and installed the other new one in its place. restarted the Rover and it idled fine, no codes, no restricted performance. i let it idle for a few minutes while i moved my '04 Discovery out of the way and then took the LR4 on a test drive. it ran great and the acceleration felt smooth.

not sure why i had issues with the idle when i first installed the new MAFs, but it is driving fine for now with them in.

 

[jastutte]

i'm still getting the restricted performance mode happening every 130-150 miles. the check engine light never comes on and we can get the LR4 to reset itself by turning it off and waiting 10-15 minutes. then in 130-150 miles it does it all again.

will there be codes present even without the check engine light? do i need a LR specific code reader to pull them?

any particular direction i should be looking?

 

[Hugh166]

Even with the non LR specific code reader engine codes should come up. To start next time it has restricted performance scan it while it is running and before you shut it off. Get the info out as it is happening and make sure to somehow record the code numbers

 

[jastutte]

pulled some codes today with the Foxwell NT. as I said previously, i cannot pull any codes with the Land Rover specific software but was able to with the generic OBD2 software.

Stored Codes, none
Pending Codes, P0500 Vehicle Speed Sensor A
Permanent Codes, P2135 Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation; U0402 Invalid Data Received From TCM; P2105 Throttle Acuator Control System Forced Engine Shutdown; and, then two (2) more P2135 codes.

 

[jastutte]

after doing a little more research and reading i decided to dig into the engine bay the other day. pulled the plug off the TPS and gave both ends a cleaning. i noticed the silicone(?) dust moisture seal was torn and bunched up and simultaneously realized the plug had come off far too easily. i pulled the torn seal out and seated the plug fully and securely on the TPS. two tanks of fuel, these fuckers have tiny fuel tanks, and over 300 miles later and i have had no issues with the Restricted Performance mode. later i'll track down a new/used silicone seal and install it on the plug. my current working hypothesis is that the bunch/torn seal was not allowing the plug to seat properly and giving the occasionally low voltage or improper voltage readings which cause the
Restricted Performance mode every 150 miles or so.

the only other thing i did was to turn the LR4 on to the ON position and then depress the skinny pedal 10-15 times. some reading had suggested that this may free up and clear debris in the potentiometer attached to the pedal that syncs up with the TPS.

regardless, i'll update this post as needed.