The throttle thing

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Bushtoy

Bushtoy

Well-Known Member
Posts
1,998
Location
South Africa
:mad: Anyone got any ideas. 110 Def TD5. Runs fine until I go over about 50% throttle, then runs rough and does not give the same throttle response. Switch it off and back on again and runs fine until I need 50% or above throttle. Thought maybe the potentiometers in the throttle body were stuffed so I got a new one...does exactly the same. Even cleaned all the electrical contacts/plugs in the loom. No joy. My little brain is now fried.:eek: So now I turn to the brains of the world.:confused:
 
what's the boost on the turbo? it should be 1bar on a standard td5. when you 'overdrive' the turbo to over 1.2 bar, it starts to act up, which can sometimes cause the eratic behaviour.
 
What do you mean by "runs rough" ? Do you mean it is slower to respond, or does the engine actually become less smooth?
 
lightning said:
What do you mean by "runs rough" ? Do you mean it is slower to respond, or does the engine actually become less smooth?
Click to expand...


:confused: It runs as though one or two injectors are not fueling properly, marked vibration at around 2500rpm, and very slow to respond to throttle inputs. Also, you kind of need more throttle input to get the same performance as before it went rough. If, after this has happened, I stop and pull off in first there is no feeling of sharp acceleration when the boost comes in. If I stop and switch off and then restart, performance is back to normal and you feel the boost as it builds. I kinda am into thinking that either one of my injectors is playing up, or the wiring loom is breaking down at higher demand. The injector harness has been replaced some 2000km ago coz it was oiled up, but none had reached the ECU.
 
It sounds like excess boost to me, as the other chap above suggested. Maybe the wastegate has jammed or there is an air leak. I believe that the ECU cuts the power in these conditions and it's felt as a shudder as the boost is limited. The ECU will then assume a sort of limp home mode until you restart it.
Somebody on the forum with more technical know-how should be able to elaborate on this.
 
Hi, My TD5 90 started having a problem like this. It was an intermittant problem with the fuel pump. The dealer did a pressure check (should be 4Bar) as per the advice i was given on this forum. If you get a consistant pressure reading then at least you can eliminate fuel pump from the equation. My problem only happened if i attempted anything above 50mph. All good now though!!
 
Bushtoy said:
:confused: It runs as though one or two injectors are not fueling properly, marked vibration at around 2500rpm, and very slow to respond to throttle inputs. Also, you kind of need more throttle input to get the same performance as before it went rough. If, after this has happened, I stop and pull off in first there is no feeling of sharp acceleration when the boost comes in. If I stop and switch off and then restart, performance is back to normal and you feel the boost as it builds. I kinda am into thinking that either one of my injectors is playing up, or the wiring loom is breaking down at higher demand. The injector harness has been replaced some 2000km ago coz it was oiled up, but none had reached the ECU.
Click to expand...

It does sound like it's a bit of an over boost problem, sometimes it can be an over boost solenoid fault or the variable vain/nozzle turbo sticking causing it to over boost which the solenoid then notices and puts it into limp home mode. Variable vain/nozzle turbo's are designed to increase boost low down but then the vains need to go back to their original position to avoid over boosting the turbo, sometimes these vains get clogged with oil and soot and get stuck and the vacuum operating the actuator is not strong enough to move them. If it was an air leak it would run rough all the time with clouds of smoke coming out of the back and making odd noises. They have had various wiring harness plug problems and throttle position sensor faults but these would be a constant fault through the rev range. I would'nt try and fix it yourself just incase it's none of the above, take it to Land Rover or to a decent specialist, expensive i know but so is miss diagnosis, modern engines are nearly impossible to accurately diagnose without diagnostic equipment.

Regards

Riggaz
 
Check the wastegate actuator rod can move freely - they can sieze.

Unplug the ECU connector block - should be under the drivers seat, check it's not full of oil. The early TD5's had a nasty habit of forcing engine oil down the injector harness (or something like that - someone will correct me if that's wrong) and into the ECU. I believe it was a recall for pre 2001 cars (certainly Discos, not sure about Defenders but it's the same engine after all) so you might want to check that's been done if you find oil in the ECU connector.

Cheers,
 
Adz said:
Check the wastegate actuator rod can move freely - they can sieze.

It's not usually the actuator that siezes Adz it's the variable vane's in the turbo that the actuator is trying to move that get stuck. You can sometimes free them with a large dose of Forte diesel treatment but if this doesn't work you're into new turbo territory.

Best Regards

Riggaz
Click to expand...
 
:D Thanx for all the advice guys!! All the suggestions got me to thinking, and think I have found the problem. Did a check on the waste gate with a vacuum pump and it did not move. Moves freely if you move it by hand though, so got a new one and now running like a dream. Think that maybe the diaphram on the wastegate is stuffed [has 310,000km on it already] Next job is gearbox overhaul....bearings are noisy. Is it a major job or pretty straight forward. I have a pretty sound knowledge of engine/gearbox innards coz i am damned inquisitive....like to know what makes things tick.:confused:
 
Bushtoy said:
:D Thanx for all the advice guys!! All the suggestions got me to thinking, and think I have found the problem. Did a check on the waste gate with a vacuum pump and it did not move. Moves freely if you move it by hand though, so got a new one and now running like a dream. Think that maybe the diaphram on the wastegate is stuffed [has 310,000km on it already] Next job is gearbox overhaul....bearings are noisy. Is it a major job or pretty straight forward. I have a pretty sound knowledge of engine/gearbox innards coz i am damned inquisitive....like to know what makes things tick.:confused:
Click to expand...

Glad to hear you've got it sorted Bushtoy, Adz hit the nail on the head then, top man. It is a major operation, it's gotta come out for starters.
 
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