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help with odd LR Discovery problem

This is a discussion on help with odd LR Discovery problem within the General Help forums, part of the LSx Technical Help Section category; Not getting any response over at the LR board yet so I figured Id try here. 00 Land Rover Discovery ...

  1. #1

    help with odd LR Discovery problem

    Not getting any response over at the LR board yet so I figured Id try here.

    00 Land Rover Discovery II

    Start the car up fine, runs fine and smooth. As it warms up, the idle drops but when the motors up to temp it starts to shutter at idle like it wants to stall (but doesnt) at like 680-740rpm back and fourth. it shakes the car like its right on the edge, but still runs. any gas above that its baby smooth all the way up the revs.

    no missfire or knock detected, but there are pending codes that keep changing. ive gotten 140 160 139 then 135 155. They are all o2 related.

    i watched the o2s from a cold start, they all read .445 until the problems start with the rough idle, as they come alive, the problem starts along with it. i noticed they are roughly .425-.460 range (rough recall) and change slowly, unfortunatly i only have a 2 second refresh on the scanner right now so its hard to see any irradict behaviour in between. i did notice however that b1s2 stays at .445 the entire time... but being post cat, i didnt think that that would even have any change in motor behavior no?

    thanks all, ill have access to better scanner tomorrow i hope to get some nice graph data goin with faster refresh, right now all i have is an ultraguage, works ok for basic data but is sloooow and limited in sensor availability like maf data.

    also saw that both bank long term fuel trims where at 25 but im not sure if that matters any.

  2. #2
    Moderator Cutlass's Avatar
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    Quote Originally Posted by grandkodiak View Post
    also saw that both bank long term fuel trims where at 25 but im not sure if that matters any.
    Yes, thats your problem. Was it +25 or -25 LTFT?
    Something is telling your computer to dump fuel in like crazy. Possiblly a bad MAF or O2 sensor or something else.

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    Quote Originally Posted by grandkodiak View Post
    Not getting any response over at the LR board yet so I figured Id try here.

    00 Land Rover Discovery II

    Start the car up fine, runs fine and smooth. As it warms up, the idle drops but when the motors up to temp it starts to shutter at idle like it wants to stall (but doesnt) at like 680-740rpm back and fourth. it shakes the car like its right on the edge, but still runs. any gas above that its baby smooth all the way up the revs.

    no missfire or knock detected, but there are pending codes that keep changing. ive gotten 140 160 139 then 135 155. They are all o2 related.

    i watched the o2s from a cold start, they all read .445 until the problems start with the rough idle, as they come alive, the problem starts along with it. i noticed they are roughly .425-.460 range (rough recall) and change slowly, unfortunatly i only have a 2 second refresh on the scanner right now so its hard to see any irradict behaviour in between. i did notice however that b1s2 stays at .445 the entire time... but being post cat, i didnt think that that would even have any change in motor behavior no?

    thanks all, ill have access to better scanner tomorrow i hope to get some nice graph data goin with faster refresh, right now all i have is an ultraguage, works ok for basic data but is sloooow and limited in sensor availability like maf data.

    also saw that both bank long term fuel trims where at 25 but im not sure if that matters any.
    You have a V8 don't you? You need to check your valve cover gaskets and consequently your coils. Oil leaks from the valve covers onto the coils, shorting them. That is probably why your getting O2 codes. As the coils near the throttle body decay(misfire) they interfere with the signal causing a rich condition which dumps fuel into the cylinder. You know the rest.
    This is common with AJ V8 engines especially ones built before 2004/2005. Ford seemed to get a handle on it by then. If you visited any Jaguar/Rover/Lincoln site and did a search you would see the trend.
    The fix is relatively easy, if a bit costly, replace the gasket and don't mess around just replace all the coils and spark plugs.
    Last edited by SSnow; 03-11-2011 at 05:35 AM.

  4. #4
    actually it just got alot worse, i just got my old laptop up and running with autoenguinity, what the holy fuck is going on:


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    Quote Originally Posted by grandkodiak View Post
    actually it just got alot worse, i just got my old laptop up and running with autoenguinity, what the holy fuck is going on:

    Click for full size
    It looks like you smoked the O2 sensors and maybe the cats.

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    The way it sounds is that it's starting it right as it enters closed loop. Do those vehicles have a.i.r. pumps on them? It would also be handy to know if your trims are + or - 25. It could be a few things really. How many miles are on your O2's? 135 and 155 are really the only codes that would pertain to this as those are the only front sensor codes you have. They're heater performance codes. If they have a bunch of miles on them you may want to just swap those out either way. My first guess would be O2 codes. Might not hurt to make sure your air pump (if you have one) isn't running all the time causing a false lean and lastly look at your engine coolant temp in the scanner and make sure it's correct.

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    Quote Originally Posted by grandkodiak View Post
    actually it just got alot worse, i just got my old laptop up and running with autoenguinity, what the holy fuck is going on:

    Click for full size
    now that's an impressive code list. I would say some of that *might* be due to it almost stalling and recovering. I would reset those and see which ones come back.

  8. #8
    i was watchin and the o2s where reading .445, then 0... then .445 then 0. very wierd.

    but i got nervous now, crank po sensor and maf problems? what the holy hell is going on? could it have all these problems and still be even to run at all?? pretty damn impressive because it runs smooth as hell at anything above idle... cold or warm.

    ok o2's are $75 each for the fronts, cats might be dead but waht about all that other stuff now?

    it has secondary air, but i dont know anything about them. how would i know if they are working or running?

    yea 4.0 v8.

    idk if its just land rover not being general obd2 friendly, i know they have alot of thier own shit goin... but niether scan tool pic up any maf data. if i let it idle, and unplug the maf to see if its working or if its dead, will there be any difference in what i can hear/feel in the idle?
    Last edited by grandkodiak; 03-10-2011 at 08:27 PM.

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    Quote Originally Posted by grandkodiak View Post

    but i got nervous now, crank po sensor and maf problems? what the holy hell is going on? could it have all these problems and still be even to run at all?? pretty damn impressive because it runs smooth as hell at anything above idle... cold or warm.

    yea 4.0 v8.

    idk if its just land rover not being general obd2 friendly, i know they have alot of thier own shit goin... but niether scan tool pic up any maf data. if i let it idle, and unplug the maf to see if its working or if its dead, will there be any difference in what i can hear/feel in the idle?
    How many miles are on the vehicle?

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    Quote Originally Posted by grandkodiak View Post
    i was watchin and the o2s where reading .445, then 0... then .445 then 0. very wierd.

    but i got nervous now, crank po sensor and maf problems? what the holy hell is going on? could it have all these problems and still be even to run at all?? pretty damn impressive because it runs smooth as hell at anything above idle... cold or warm.

    ok o2's are $75 each for the fronts, cats might be dead but waht about all that other stuff now?

    it has secondary air, but i dont know anything about them. how would i know if they are working or running?

    yea 4.0 v8.

    idk if its just land rover not being general obd2 friendly, i know they have alot of thier own shit goin... but niether scan tool pic up any maf data. if i let it idle, and unplug the maf to see if its working or if its dead, will there be any difference in what i can hear/feel in the idle?
    I would say your O2's are shot.......that would be my guess.

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    Quote Originally Posted by grandkodiak View Post
    100,800
    Another thing to look at with these engines as they get up there are the cam tensioners. They are plastic in early models and are prone to wear and early failure. A usual sign they are going is excessive noise from they front of the engine.
    http://www.jagservice.net/jaguar_v8_...tensioners.htm

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    clogged cats would be my guess...

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