Hello everyone,

I certainly didn't mean to make this as long as it did but its two parts: Current Problem and Vehicle History:



Current Problem:

Purchased a 2011 Full Size Range Rover Supercharged (w/ locking rear) just over a year ago with 70k. After I bought it got a random misfire codes in several cylinders and have used various injector cleaners (mostly BG44k) and the CE light would occasionally come one, but most of the time it stayed off.

Now there is 96k miles on the vehicle and the CEL has stayed on for the past four weeks with the following codes:

• P0300 Random Misfire Detected
• P0302 Cylinder 2 Misfire Detected
• P0304 Cylinder 4 Misfire Detected
• P0306 Cylinder 6 Misfire Detected
• P0308 Cylinder 8 Misfire Detected
• P0316 Misfire Detected On Startup (First 1000 Revolutions)

Symptoms:

• Not the smoothest idle
• There has been a few moments of "chugging" while driving.

Let me preface by stating that I DO have an Extended Warranty (CarSheild serviced by American Auto Shield), and yeah they aren't great to deal with, but they did replace a noisy supercharger saving around $3,500. I pay $107.00 /mo. since February.

Also I only run PREMIUM ONLY. This is my wife car and she won't cheat with lesser gas, not once.


What I Have Done:

Took it to the dealer three times to CYA (gotta play by the extended warranty rules and make sure your problems are taken care of quickly and well documented).

• MARCH: First Dealer Visit: Multiple Missfire detected in 6 out of 8 cylinders, they recommended fuel system cleaner, and put BG44k in the tank. Cause Undetermined.
• MAY: Second Dealer Visit: Multiple Misfire detected. Cause Undetermined.
• JUNE: Third Dealer Visit: Multiple Misfire detected, gas cap was loose, they said: "Cause Undetermined. Misfire faults and low fuel level may indicate the engine ran too low on fuel at one point.
• AUGUST: Independent Rover Mechanic: My trusty rover mechanic suggested all of the injectors are "dirty" and called to file a claim with the warranty company which rejected the claim because they don't cover part failure due to "dirt, debris, etc, etc". Not sure if that was the best way for him to describe the problem, but it is what it is.

Note: There is no fuel smell in the exhaust or in the valve cover (symptoms of a bad High Pressure Fuel Pump).

Also the previous owner has a receipt from the mechanic for the EXACT same problem (2,4,6,8, random misfire, startup, and rough idle). Even that mechanic said it was "Undetermined".


So where do you suggest I go from here? Is there something else that could cause the misfires other than "dirty" injectors?



Vehicle History:

This is definitely got to be my favorite vehicles but my gosh the repairs in the past 12 months include:

1. New Supercharger (covered by extended warranty)
2. New Passenger Airbag (LR Recall)
3. New Rotors and Brake Pads (Front and Rear)
4. New Passenger Front Caliper
5. All New Ball Joints and Upper and Lower Control Arms (Serviced by Local LR only Mechanic)
6. AC Service
7. Rear Tailgate Gas Struts
8. New Cabin Filer (General Maintenance)
9. New Air Filters (General Maintenance)
10. New front and rear wiper blades (General Maintenance)
11. New Gas Cap
12. All new tires yesterday (the Bridgestones were still half life, but just put on some Nitto Terra Grasper G2's). Love 'em.
13. Four Oil Changes
14. Multiple cans of injector cleaner and only used when the CE light would come on.

All together my out of pocket cost (not including the supercharger replacement), is just under $4,800 doing most of it myself. Not complaining because like I said, Ive owned several rovers of the past 18 years and made it through the disco years so I know what I was getting into.

FYI, I also have over $14,000 in repair receipts from the previous owner including, timing chain, transmission, air suspension, air suspension compressor, supercharger, etc.


But one has to ask: Is there any reprieve?


Thanks so much in advance!

 

Did you figure out what is going on with your wife's car? My wife's car is doing the exact same thing. The idle hunts slightly under load, but not at idle, seems to stumble somewhat between 1800 and 2200 rpm but seems fine below and above that. No leaks, no smoke, no CEL most of the time, only twice in the past few months, and then it goes away on it's own.

Also have similar repairs done, timing chains, actuators, supercharger, etc. Also done the BG44k, premium fuels, etc.

 

Many of the timing tool kits don't "fit" properly and unless modified, will cause the vehicle to be out of time during assembly after timing chain replace. Typically, this will not only cause a misfire, but also a Cam/Crank correlation code. However, if its in just enough time to not set a correlation code but out enough to misfire, it will be tricky to catch.

I'm not sure the injector cleaner does much for Direct Injection injectors. Although debris can cause issues, its usually not something that can be cleaned. If ANY piece of solid (metal, dirt, etc..) makes it past the fuel filter, it will end up in an injector. DI injectors have very small orifices and it doesn't take much for foreign material to clog it. You can clean varnish and carbon buildup, you can't "clean" out debris with chemicals. A piece of debris will either clog an orifice, or due to the very high pressure, can actually scratch or imbed in the sealing seat in the injector and make it drip.

A failing O2 sensor could cause that. If it falsely reports a rich fuel mixture, the ECM will constantly pull fuel from that bank. Not all failing O2 sensors set an O2 sensor fault.

I have seen plugged converters cause misfires on a whole bank, but not usually intermittently. Once a converter is plugged, its always plugged and usually always shows symptoms.

 

I am hoping that the timing tool kit was correct in my case as the repair was performed at the dealer. The hunting was present prior to the timing chain/actuator replacement, so I don't believe it to be that. I do have a downstream O2 sensor here so I can try that to see if it helps, and if not maybe go to the cat itself. The P0316 though led me to believe that it had to be something other than O2 or cat since those don't have much input until that car has reached operating temp and the PCM is in closed loop? Again, the strangest part is that the codes will appear, and then go away just as fast as they appeared. The car has lit the CEL twice in say three months.

 

I got kicked hard by an improper crank tool, id love to hear a dealer tech chime in on whether or not the factor tool only fits in the larger window. If you or your local rover tech has access to a scan tool with live data, you can simple check using the values fr cam position 115 and 75, ill have to double check but at 3 windows , off i think i was around 139 degrees. Threshold is 135 just enough to set correlation faults, but i suspect being 1 or 2 windows off you may not set a fault unless it affects the adjustable timing. P316 sounds like its just stating the misfirs occur when cold, also scan tool freezerame data could verify that. Arnt cylinders 2,4,6 and 8 all on bank 2(drivers side)?

 

I'd assume that if the timing was off enough to trigger the CEL, it would not be a once every three months or so occurrence? Those cylinders are all bank 2 which I thought was passenger side (left hand drive).

 

This engine doesn't use traditional European numbering but instead, as a Ford product, uses American numbering. So 1,3,5 & 7 are passenger side and 2,4,6 & 8 are driver's side. For clarification, Bank 2 is on the LEFT when sitting behind the steering wheel.