Can anyone help diagnose my idling fault ?

[Allan]

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

[albundy]

Had similar problem and it was the fuel tank valve. However check all the vacuum hoses as well.

Rgds

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

[Will308]

I've been chasing the cause of this condition for about 3 years. If you find out what it is please let me know. I've had it to 3 different mechanics and I haven't found the cause.
Thanks,
Will

[Bill R.]

the idle problem you describe, the most likely is the vacum plate on the back of the intake manifold or pcv plate as some describe it... Heres a post
from Winfred thats saved in the repair section here on the pcv plate

Other very likely possibilities are the intake manifold gaskets, this is also very common on the m60. Also if its a nikasil block the first symptom that most people notice when the nikasil is going away is a lumpy idle.
Since you're in England thats not as likely but there were some bad nikasil blocks in England and the rest of europe.

The m60 has always had a little bit of a lope to it, due to the cam, its part of the performance car mystique

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