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I have owned a 1996 Peugeot 406 2.0-litre petrol 16v LX from new and for the last year it has had an intermittent fault.

It had covered 165,000 trouble free miles up until this fault. Sometimes it will rev up and down erratically when started from cold, and once on the road it will momentaraly falter/hesitate for a split second and then run normally. Other times it will just cut out while idling, but it always starts OK.

Other times it will jerk as I lift on and off the throttle, and, associated with this, if I engage neutral while coasting the revs only drop down to 1200rpm, and only drop down to 950rpm once car has stopped.

Now and again the fault light comes on, but not while the fault is occuring and it records "Irregular fuel delivery?"

I have so far renewed the following:-
Throttle Potentiometer
Stepper Motor
Oxygen/Labda sensor
Throttle cable
Reconditioned ECU

The "Master Tech" at my dealer has reset the "Auto Adaptives" for me.
This car is in excellent condition and drives beautifully 99.9% of the time,and I really need help fixing this, because it's quite hairy when it cuts out while I am turning or approaching lights.

Asked on 3 April 2011 by 406roadrunner

Answered by Alan Ross

Sounds as though you have tried very hard to erradicate the problem.
Not sure if you have an air temperature sensor fitted to your intake manifold(sometimes they are fitted inside the MAF sensor)but if you have it would be worth checking to see if it is working okay. A faulty sensor will result in an incorrect fuel/air mixture which in turn results in poor idle quality, stumbling on acceleration and surging when the engine is warm.
In addition if the air temp sensor is faulty it may effect the EGR valve (exhaust gas recycling). I would recommend that the EGR valve is checked anyway.

Over and above that you may want to check that you do not have any vacuum leaks and also check for a restricted catalytic converter.

Tags: technical issues