Allan
04-20-2004, 04:00 AM
The issue I am about to describe has been bugging me for a few weeks now so any help or advice will be much appreciated -
CAR - '94 530i V8 (M60) Auto, 122k miles
OWNER - Engineer, competant in mechanics and basic electrics/electronics - Keen DIY' er who avoids the motor trade if at all possible.
FAULT - Lumpy idle, as if one or more cylinders are mis-firing but not all the time. This morning for instance it felt perfect for the whole of my 30 minute drive to work. Sometimes, at idle,the engine will suddenly falter and even stop. Occasionally there is a slight hesitation when moving off. At all higher speeds it runs perfectly. The fault occurs randomly and I can determine no correlation with conditions or with engine temperature.
BACKGROUND - The engine has behaved impeccably for the 2 years I have owned it, normally at idle it is barely possible to detect that the engine is running at all without looking at the rev counter which is always exactly at 600rpm.
The engine is in excellent mechanical condition and uses no oil. Average urban consumption is about 20 mpg as shown on the trip computer
ACTIONS
Since the fault appeared in recent weeks since I have -
Checked and cleaned the spark plugs - they look as new
Cleaned and applied dielectric grease to the HT connectors
Cleaned and inspected the ICV - it is perfectly free
Visually checked and applied cleaning fluid to every electrical connector I can find including the ECU multi plug.
Admittedly the fault is a minor one with which many people would live, but I know that something is going wrong and have a desire to cure it therefore any guidance, expert or otherwise would be welcome. Where should I look next ? Could it be a fuel injection rather than an ignition problem ?
Would a professional diagnostic check track it down ?
If you have any material that may help please email to allan@a14alk.fsnet.co.uk or a.kennedy@hud.ac.uk
Many thanks in advance
CAR - '94 530i V8 (M60) Auto, 122k miles
OWNER - Engineer, competant in mechanics and basic electrics/electronics - Keen DIY' er who avoids the motor trade if at all possible.
FAULT - Lumpy idle, as if one or more cylinders are mis-firing but not all the time. This morning for instance it felt perfect for the whole of my 30 minute drive to work. Sometimes, at idle,the engine will suddenly falter and even stop. Occasionally there is a slight hesitation when moving off. At all higher speeds it runs perfectly. The fault occurs randomly and I can determine no correlation with conditions or with engine temperature.
BACKGROUND - The engine has behaved impeccably for the 2 years I have owned it, normally at idle it is barely possible to detect that the engine is running at all without looking at the rev counter which is always exactly at 600rpm.
The engine is in excellent mechanical condition and uses no oil. Average urban consumption is about 20 mpg as shown on the trip computer
ACTIONS
Since the fault appeared in recent weeks since I have -
Checked and cleaned the spark plugs - they look as new
Cleaned and applied dielectric grease to the HT connectors
Cleaned and inspected the ICV - it is perfectly free
Visually checked and applied cleaning fluid to every electrical connector I can find including the ECU multi plug.
Admittedly the fault is a minor one with which many people would live, but I know that something is going wrong and have a desire to cure it therefore any guidance, expert or otherwise would be welcome. Where should I look next ? Could it be a fuel injection rather than an ignition problem ?
Would a professional diagnostic check track it down ?
If you have any material that may help please email to allan@a14alk.fsnet.co.uk or a.kennedy@hud.ac.uk
Many thanks in advance