406 HDi engine running fault

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

 

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.)

 

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

 

Hello,

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