Unusual but slightly disconcerting fault

lightning · Nov 19, 2019

Two or three times recently, after accelerating at low RPM (under 2,000) my 2005 Defender TD5 has carried on accelerating when l took my foot off the gas pedal.
It’s quite sudden and strong acceleration
Obviously l have immediately pressed the brake to slow the vehicle down at which point the self acceleration stopped.
I was concerned it could be the start of diesel runaway, would this be the turbo bearings?
If not then what could be causing this to happen?
The throttle pedal was replaced within the last year with a brand new LR one.
How can l check that the turbo is OK? It’s done 116,000 miles.

sierrafery · Nov 19, 2019

To rule this out you should connect a tester on live data and see the TPS inputs when the symptom occurs, if track 1 drops and 2 grows when you let the pedal then the TPS is ruled out but if not the problem is somewhere on that circuit, if no tester available push the throttle few times at that very moment and if it recovers there's the problem, eventually take it out f gear to see how much that revs are growing on theyr own

IMO the turbo can't have any involvment in this, i suspect a management issue

lightning · Nov 19, 2019

Thanks for the advice.
I thought that if the turbo bearings had failed then the oil could get into the engine and it run on that.
Next time it happens l will take a chance and press the clutch, and the gas pedal a few times hopefully the engine won’t go to peak RPM

It’s not done it for weeks until today, so l doubt l would be able to monitor the engine under fault conditions.

l did fit a cruise control kit earlier this year. It was an official one not home made but the fault didn’t occur before that.
It may be coincidental but l could try disconnecting the cruise wiring harness.

sierrafery · Nov 19, 2019

lightning said:
l did fit a cruise control kit earlier this year. It was an official one not home made but the fault didn’t occur before that.

AAAA-haa --- IMO that's the root of the problem, is it clearely stated on that kit that it works with td5?

lightning · Nov 19, 2019

Yes
It’s a Nakatanenga kit and it works fine.

It’s basically two buttons and a wiring harness

sierrafery · Nov 19, 2019

lightning said:
Obviously l have immediately pressed the brake to slow the vehicle down at which point the self acceleration stopped

that points also to cruise control missbehaviour as it's disabled by the brake switch... IMO if it was that so called "diesel runaway" the brake would have not had any effect whatsoever, not even the ignition and it usually comes with a lot of smoke.... also i dont see any way for oil to get into the cylinders from the turbo on a Td5

lightning · Nov 19, 2019

OK

Thanks for the advice.
I better check the cruise control kit/wiring then.

Unusual but slightly disconcerting fault

lightning

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sierrafery

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lightning

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sierrafery

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lightning

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sierrafery

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lightning

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