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Discussion Starter · #1 ·
Greetings I am roverfox9 and I have an annoying mystery that I can't seem to solve. Whenever I start my 1999 Disco she sounds beautiful, idles nice and revs fine. However when I put her in drive and add some gas to it she takes a long time to get up to speed, and when I go to add more gas to her she loses power as if I took my foot of the gas. Afterwards when I lightly add more throttle she wont go any faster than 18-20 mph; I am at a loss here.

I have gone on many forums and replaced just about every sensor/thing that they say could be the problem, the Crankshaft Positioning Sensor, the Throttle Positioning sensor, the Stepper Motor, Sparkplugs and Wires, and even the Alternator. Again I am at a loss I have no idea what it could be, my fuel pressure is fine when at idle if this info would help.

If I may ask for some tips or info. If anyone else has had this elusive problem; thank you.
 

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Your description really sounds like a restricted exhaust.
 

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Discussion Starter · #5 ·
I replaced the fuel filter about a half a month ago, and it is still giving me issues. When I bought my Land Rover it also included the big manual that I was told is worth a couple hundred bucks and I have not seen anything concerning a second fuel filter under the fuel pump as mentioned by p76rangie.

I forgot to mention in my list of replaced parts that I have a new fuel filter.

A funny thing is that when I start my Disco and drive it cold it runs fine, but when it gets up to temp it starts losing power until I am going no faster than 18-20 mph as mentioned above.
 

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Discussion Starter · #7 ·
I do have a code reader and have tested my Disco. And no codes show up o_O. I have used it a number of times on her and get nothing except an O2 sensor but I had the O2 cleaned. And redtruck12 mentioned that I could have a restricted exhaust, but I would think that would throw a code on the reader.

This issue is so strange
 

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Hmmm... permit me to think out loud:

Presumably, you have checked for squashed exhaust pipes; if the cats were clogged, that would throw a code (I had mine changed last year for that very reason)

You said the vehicle runs well when cold but the problem surfaces when she warms up. Others will explain better than me but the major difference when the engine reaches normal temperature is a leaning of the mixture. (There's probably changes in the timing too...) What does the exhaust look like when cold and hot? Is it really "sooty" when hot? Note: these engines do run chronically rich all the time. Is it possible the engine is flooding? But that should 'throw' codes.

When you say: "Afterwards when I lightly add more throttle she wont go any faster than 18-20 mph", describe how the vehicle is running.... is it pulling smoothly but just "held back" or is it coughing, missing, hunting etc.

Final question: when she is "labouring" when warm, if you then put it in neutral, will the engine recover and rev properly until you select drive again?

Could this be a transmission problem or is your transmission brake binding as it warms up? Both pretty unlikely...
 

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I have not seen anything concerning a second fuel filter under the fuel pump as mentioned by p76rangie.
On the bottom of the actual pump, you will find a filter like the one below. They stop the crap getting into the fuel pump. They do clog up over time.

My other suggestion is to put injector cleaner into the fuel tank.
 

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Discussion Starter · #10 ·
First off thank you p76rangie for the tip and pic.

Well my pipes seem fine, a minor crack near the end of the exhaust that leaks water but that is it. As for the smoke, it is white when cold and seems normal when she is up to temp. As for the power situation, when I add more gas it revs higher smoothly but the power lose is immediate as if I took my foot off of the gas. Yet I am flooring the gas peddle. And when I am in neutral it revs fine no problem, but when in drive she acts up yeesh. My transmission seems ok, no strange sounds or vibrations when I put it in park, drive, or neutral. I hope this info will help Mr. Pavel
 

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Still sounds like a plugged exhaust to me.
I would do an exhaust back pressure test and either confirm it as bad or good.
Back pressure should be less than 1psi

If you are not sure how to do it
Google "how to perform a pre catalyst pressure test"
 

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Have you done a fuel pressure check. I had this in a D1 and it started showing systems of problems when pulling boat, and harder starts. Fuel rail has port, screw on fuel pressure gauge and check while running 37psi-41psi.
 

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Same thing happened to mine. At night started it and let it run for about 30 min. Passenger side cat started turning cherry hot iron red. Clogged cat meaning restricted exhaust. No codes thrown on mine but complete loss of power. Good compression. Good spark. Good air. Everything seemed fine but it ran like crap.
 

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sudden loss of power - Discovery 1 2500 TDI 1993

LR Discovery 1 2500 TDI 1993. Located in Tanzania, East Africa
Cruising nicely at just over 100 kmh when hit by sudden loss of power and huge clouds of black smoke. Pulled off the highway and checked under the hood - nothing amiss to see. Engine would idle fine but not rev beyond about 1500 rpm. Not overheating.
Needed to be towed home however today the car runs fine.
What do I look at first?
 

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Discussion Starter · #17 ·
Hello, sorry for late response. Happy New Year!!

Ok first off when I put my Disco in drive it does roll forward. I don't really have an incline to use since my driveway is flat. But it seems alright when it creeps forward. I have checked the fuel pressure and it seems fine when in park or neutral, but when in drive it drops a few notches. Now when I start it and apply throttle it will die on me, unless I keep giving it throttle. I bought a new pressure regulator and see if it would fix that problem.

I think once I install the new regulator I will also check and see what the cat looks like. it probably is the cat but it is really strange that it is acting like a fuel problem.
 

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Discussion Starter · #18 ·
Well my Cat does not turn red hot so I think it is safe to say it is not plugged. I put the old TPS back on and now my Disco drives fine. However the idle is odd, when cold starting it idles really high and needs adjusting. Driving around is fine and all in good up to temp but when I turn it off and back on the idle is so low it dies o_O. I have to keep revving it until I can get it into drive, then it is fine again. Any thoughts on what it could be?
 
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