320i running issue

[andyf]

In desperation I am posting this in the hope that someone might be able to help with a problem that has been puzzling me for the 6 years that I have owned my car. I have tried everything I can think of. The car drives well and pulls, and I have driven it all over France for the past few years with no problems but the symptoms are:
For a 6 cylinder it is not running smoothly and seems to be missing but not in a regular way.
The engine warms up and hot air comes out of the heater but the temperature gauge on the dash never reaches the centre.
Even when warmed up the idle revs never fall below 1000 (My previous 320i idled at 700/750 when warmed up)
There seems to be a smell of unburnt fuel in the exhaust even when warmed up.
Over the years I have tried pretty well much everything I can think of with no joy, if anyone can help it would be greatly appreciated.

Andy

[aimlessrock]

First things first-When were the injectors last overhauled?

[markus_74]

Injector, ignition rotor, sparkplug cables, and least do compression test

[andyf]

I have just done the injectors about a month ago and also have checked ignition rotor and plug cables; I havn't yet done a compression test but will do now, thanks

[BenHar]

Temperature gauge on an M20 should sit at just above the quarter mark.

Check for air leaks in the induction side. And that the TPS is working and adjusted correctly.

Has the throttle stop screw been adjusted? It should not have been moved from the factory setting but often has.

Ben

[Brdjo]

Temperature gauge on an M20 should sit at just above the quarter mark.
Ben

Are you sure? I think it should be right in the middle @ 84-88 celsius, fully warmed up ofc.

If TPS and blue temp sensor are ok, high idle speed is most certain caused by vacuum leak.. alson it is important to make sure that the signals from TPS and blue temp sensor is reaching to the ECU..

[paultv]

My M20 sits at a quarter when hot, it has an 80c stat fitted, although it's a 2.5i

Paul

[Brdjo]

Ups, I am sorry, that is right xD I miss understood 80 c is middle position...

[Carmo13]

Just to back up what has already been said, dont fret about the temp guage as mine reacts the same and from what i have gathered from a few years on this forum, so does every other 6 cylinder E30.
I would be having a very patient and thorough look for air/vacuum leaks.

[Brianmoooore]

One thing that's missing from this thread is what version (age) of the 320 in question is. Early 2.0 litre engines have a horribly primitive engine control system which is difficult to keep working properly, while the mangement on post facelift engines is generations ahead.
To idle at 1000 RPM the engine must be getting excessive air to be able to do so. The first thing to do is to find out exactly where this excess ir is getting through to the engine.

[Speedtouch]

The OP's other posts suggests he has a 1989 320i Cab, which should have the Motronic 1.3 setup.

Check the idle control valve is working properly - perhaps remove it and clean it out with carb/brake cleaner.

Another possibility is a cambelt installed one tooth out, which can cause subtle but annoying idle/running issues.

[andyf]

Thanks for all the replies everybody which have been really helpful. I have wondered about the timing belt before as there is slight 'pinking' when the engine is under load and as there is no method of advancing or retarding ignition timing I wondered if an incorrectly fitted belt was have an advance/retard effect. Could the low temp be caused by an over rich mixture and the unburnt fuel causing lower cylinder temps? I will have a look at the timing belt set up and check to be sure. I wonder if I have more than one problem here though as would that also explain the erratic running? The engine runs of course and I have pulled each plug cable off one at a time with no joy. Its just frustrating as its supposed to be a fabulously smooth engine! The car is a pre face lift cabbie with a 1.3 Motronic set up. Its our family car and its been all over France, done 137,000 miles and we love her!

[Brianmoooore]

To idle at 1000 RPM the engine must be getting excessive air to be able to do so. The first thing to do is to find out exactly where this excess air is getting through to the engine.