P0505-27 and P0420-00 2016 Land Rover Discovery Sport 2.0 Ford Ecoboost Engine

P0420-00-Catalyst System Efficiency Below Threshold (Bank 1)
P0505-27-Idle Control System - Signal rate of change above threshold

54,156 miles
Gasoline engine

Bought car from an insurance auction.  On first startup, multiple misfires on cylinders 2 and 3 and engine shaking very badly.

Inspected engine and found connector for number 2 spark plug boot was broken and the three pins from the spark plug boot bent and were visible.  I replaced the spark plug boot and erased codes and misfires stopped.  After clearing codes, P0505-27 and P0420-00 came back, car is burning through fuel too quickly I feel, and car when warm and in Park, has a surging idle.  Also on first start/cold start, the RPM goes very high but when I put in D, the RPM will drop down to normal.  Inspected engine again and the hose from the air intake pipe to the valve cover was missing and I also found a hole in the valve cover near where the hose enters the valve cover.  Looks like someone tried to remove the hose but broke off the nipple on the valve cover.  I replaced the valve cover and added a new hose connecting the valve cover to the air intake pipe.  After clearing codes, codes and symptoms returned.

I smoke tested the intake system and smoke was escaping from the air intake pipe near the hose clamp over the air intake pipe that connects to the turbo intake pipe.  I replaced the air intake pipe but after clearing codes, codes and symptoms returned.

The P0505-27 is for the air idle control valve and on this car, that valve is built into the electronic throttle body.  I want to replace the throttle body or replace the PCV valve.  But I want to be sure that is the problem because I already replaced the valve cover and the air intake pipe but the problem was not fixed.

The P0420 code could be a melted catalytic converter but I'm hoping if I fix the P0505 the P0420 will also go away but if the cat is melted, due to earlier misfires, then not much I can do other than get a new cat.

Any help would be great!  Thanks! 




 

Do you have access to scan data? I'd be interested in monitoring a few PIDs during the hot idle surge. MAP sensor, BARO, engine speed, desired idle speed, short/long term trims and throttle position would be a good place to start.

I can't say with certainty about the 2.0L engine, but I've personally seen 1.5L and 1.6L EcoBoost engines with idle surge problems that resulted from incorrectly setting the timing belt. Either the crank lock pin wasn't used, the wrong pin was used, or the crank was off the lock pin when the balancer bolt got torqued. You end up with an engine that's mechanically out of time, but doesn't set timing codes.

Hi! Thanks for getting back to me. Yes, I have access to scan data. I will drive around and look at the live data for those data points and report back. Thanks again.

The only thing I'm seeing is the short fuel trim rising to +14, +17, and +20 and at the same time the Engine speed is rising. My guess is that the fuel trim is rising because the idle is surging and RPM's are increasing. The other PID's, are not spiking and they are just a flat line even when the idle surge is happening.

My scanner can only show 6 data points at once so I couldn't show the desired idle speed and the long term fuel trim.  Also the desired idle speed did not have a value for me and it remained at 0...I think this is due to the limitations of my scan tool.

 

Hello I have a Discovery Sport HSE I have been having the same issues you described. I also have the one persistent code that always comes back P0505-27, I have had a new throttle body put on a new turbo put on, 3 sets of new spark plugs put on in the last eight months. Land Rover checked my timing chain it was fine. I have had thousands of dollars of Work on this vehicle and Land Rover cannot figure out what’s wrong with it. Everything I research says that that code is for the idle air control valve, which is apparently built into the throttle body, but that did not even fix the problem because I had a new throttle body put on. It starts to really surge when you come to a stop and it’s sitting in idle if you put it into neutral it stops.

Tyler posted above that when the timing is incorrect on the 1.5 and 1.6 the idle surge happens.

Plugging Tyler's advice in Google revealed a Land Rover TSB re surging idle and the P0505 code. The TSB doesn't say P0505-27 but it does have the year of my Disco, 2016, with the GTDi motor, which I'm pretty sure is the Ford 2.0 Ecoboost.

I'm going to check the timing and compare it to a waveform I found on the net. You said the dealer already confirmed your timing was good? Well in that case I really don't know what else it could be.