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Discussion Starter · #1 ·
I just bought a 2004 Land Rover Discovery 2 SE7 w/ 105k miles a couple weeks ago I love it already but am having a few unfortunate issues.

Car was fine when i test drove it and for a few days after, and then i hopped on the freeway one day and it misfired like hell, couldn't get above 50mph, i could feel it misfiring badly at idle. Got the codes read: P1300, P0300, P0301, P0304, P0307, P0308.

Took it in to a reliable local shop, they said it had the wrong plugs (Platinum +4's), replaced the plugs with NGK's and changed my oil. Car ran fine / idled fine for a couple days and pulled hard etc., no CEL light.

Two days later, same symptoms, codes read the same. Took it back to the shop, they said it must be the coils, so they replaced both ignition coil packs and the wires (STI). Car ran fine and pulled harder than ever, idle was smoothest its been. Drove it around town fine for a day.

Next day, i take it on the highway and open it up and immediately get a code (only P0304 this time). Drove it for another ten minutes on the freeway and eventually got the codes: P1300, P0300, P0304, P0305, P0307, P0308.

It seems to be idling better now and not misfiring as much, but otherwise the same symptoms persist, and i am now in over $1,100 trying to troubleshoot this.

any thoughts on what to do next? Does this sound fuel injector related? I told him about the misfiring issue the first time it happened, and his reply was "Well, the O-rings are known to become brittle and leak in these trucks", was this a potential "hint"?

Supposedly the HG was done 15k miles ago, and the previous owner was a rover enthusiast and seemed genuine... Should also note that the CarFax showed it failed emissions in December... not sure how that may relate?
 

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has the coolant level remained steady in the overflow tank? Keep an eye on that. Look for vaccum leaks. Just do a search as there are several different techniques. I.e. smoke, brake cleaner..
Concentrate on upper intake manifold, plenum, throttle body, IACV. Clean MAF sensor.
No other codes?
Run searches on "multiple misfires" on this forum and google to get different ideas what to look for.
I wouldn't run the engine except when moving on from fix to fix. Cat Converters and whatever else will get damaged by this level of cylinder misfire. The blinking CEL is for real.
 

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Discussion Starter · #3 ·
Update: took it into the shop again, they figured it to be one of the fuel injectors (1) and replaced it. Drove it for 5 miles on the freeway just fine. STarted it back up about an hour later and proceeded to drive home.. 1 mile in to the drive CEL back on, continued to drive on the freeway for the remainder of the 2 miles home..

Pretty much the same codes: P1300, P0300, P0304, P0305, P0307, P0300(twice?), P0308.

Im at a complete loss at this point... someone suggested it could be a short at or near the ECU causing false fuel trim signals to the 02 sensors?
 

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Got my rover in operating condition after a full rebuild. Everything went well for the break in but during that time I got a code for the oxygen sensors. Both upstream sensors seem to be malfunctioning but here's the thing; when I bought it it had random cylinder misfire so I replaced them both in 2014 and maybe put 30 miles in them before I parked it and started the build. Now that all the mechanicals are squared away, I'm getting misfires on cylinders 2,4,6 and codes for both upstream sensors. I ordered in new Bosch sensors from advance for $170 and change. Any ideas before I install now sensors? Bank 2 is also reading lean so that is confirming o2 sensor. The whole intake has new gaskets and all injectors were tested and cleaned before install. The only odd piece is the harness plug was butchered by the last owner and I reinstalled a factory pigtail. Any advice, and a good priest would be greatly appreciated.


Mike Russell

Age 20

2003 discovery se

Lover of Rovers
 

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Got my rover in operating condition after a full rebuild. Everything went well for the break in but during that time I got a code for the oxygen sensors. Both upstream sensors seem to be malfunctioning but here's the thing; when I bought it it had random cylinder misfire so I replaced them both in 2014 and maybe put 30 miles in them before I parked it and started the build. Now that all the mechanicals are squared away, I'm getting misfires on cylinders 2,4,6 and codes for both upstream sensors. I ordered in new Bosch sensors from advance for $170 and change. Any ideas before I install now sensors? Bank 2 is also reading lean so that is confirming o2 sensor. The whole intake has new gaskets and all injectors were tested and cleaned before install. The only odd piece is the harness plug was butchered by the last owner and I reinstalled a factory pigtail. Any advice, and a good priest would be greatly

Mike
What exactly are your codes?...
The way I see it is you possibly have lean misfires on bank 2 along with both upstream 02 codes? I am guessing p0171 &p0174.?
If that is the case
Sounds more like a vacuum leak
Knowing that you have had your beast in 1000s of pieces for quite some time now, do you think it is possible you have a vacuum leak somewhere?
2,4&6 are not all on a shared coil so you can likely rule that out. Also did you shim the rocker shafts when you re assembled the top end of the engine? (Just questioning 3 cylinders side by side)
 

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It came to all right cylinder misfire, random cylinder misfire, lean bank right, both upstream sensors and the sai gave a code. For the time that it outside, which was two years, the exhaust was open but covered with a tarp so I figure that the sensors oxidized and were not even close to what they needed to be. I did replace the sensors and had the active codes clears. Still driving it for the break in and inspection readiness and no code for about 20-30 miles so far. I got Bosch oem style o2 sensors and they seem to have done the trick.


Mike Russell

Age 20

2003 discovery se

Lover of Rovers
 

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Silly question but


Fresh fuel?
 

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The tank was dry when I put it in. I flushed the main fuel line and the fuel rail too. It started to throw codes again. It will run fine until the codes set then it will misfire. It's all right cylinders, right o2 sensor, and right bank lean. Now o2 sensors need to relay exact information for fuel ratios right? Well I figure that when the previous owner put a stupid cheap o2 sensor on and botched the harness, it changed the readings and now I'm getting all the codes for that side. I butt connected a factory pigtail on but I'm going to cut it off again and solder the connections in hopes that it will clear up the codes. And ideas are welcome and appreciated.


Mike Russell

Age 20

2003 discovery se

Lover of Rovers
 

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Soldered the wires with silver bearing solder and it fixed my problem with readings on bank 2 ?. Now engine light is off but I'm having a problem with the readiness codes. My county has emissions testing and I can only have 1 code that monitors the system not set. I have 2 and then won't clear out. The EVAP fuel monitor is still incomplete as well as the catalyst monitor. I'm not sure on how to start on either of these. On the EVAP, is the fuel tank always suppose to be pressurized? When I fueled the other day a lot of venting happened before I opened the cap all the way. I'm hoping that one of these will hit readiness status so I can get inspected and finally get a tag on this thing.


Mike Russell

Age 20

2003 discovery se

Lover of Rovers
 
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