406 HDi engine running fault

Dec 29, 2003 3 Replies
Z

Hi,



At first, my english is not perfect, Im sorry. But I try: I have 3 years old 406 HDi (66Kw with chip), mileage is 196000km and it has a serious fault. When I drive slowly with 1st or 2nd gear, car/engine not drives smoothly. It "jumps" like somebody kicks to back about every 1 sec., and when I try to accelerate speed, engine sleeps few seconds and then it starts to work correctly. With cold engine problems are more seriously than with hot engine. accelerate-effect with cold engine is like old diesel-mercedes with caravan. In highway HOT engine works well. But when I slow down speed and engine is running idlespeed, something accelerates engine smoothly +500rpm every



1 sec. Has anybody have same problem in HDi-engine? What could be damaged part? When problems starts, car`s fueltank was pretty empty, and I just thought that could it be damaged fuelfilter, if fuelpump pushed water to the filter? Filter is just renewed. I thought that some possible faultpoints could be (...could it?):


- Fuelfilter



- Air mass meter (Is it so sensitive in HDI than in TDI?)



- Turbo pressure sensor



- Gaspedal potentiometer (beside air mass meter)



- Fuel pump (in the tank)



Z Bremer


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M

So,have you removed the chip and tried the car without it. Sometimes the chips put more fuel into the engine at low speeds(my brother's car, VW Passat, chipped, jumps about a bit at low speed as well, the kangaroo effect depends on how far he has turned the HP control knob on the chip unit.)

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Z

In matter of fact, I have three different "power"-chip (whom I`m testing just now) and fault-effect is same with every chip. I havent tested car with its own original chip, because I havent codeadapter for that (yet). Anyway, I have driven thousands of kilometres with every three chips without any kind of problems => So I think that fault is not chip (bacause chip is only digital controlmap for engine working).

But now after few days fault is not so bad/pronounced than one week ago. Engine works about correctly, especially in highway above

1700rpm. But idle-speed is not stabile enough. Before fault, idle was exactly 920rpm, but now it bumps between 900-1000rpm. I have booked time to dealer for fault-code reading, but Im afraid that anything wont found. Im just thinking what kind of sesnsors relates to idle-speed? If some sensor is just unclean?

ZB

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G

Hello,

It could well be an inductive sensor, placed above the flywheel. Output voltage should be interresting to view using a scope.

Regards, G.T snipped-for-privacy@worldonline.fr

205 Diesel & turbo-Diesel :
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