M20 running rich

[BavarianBimmer]

My '89 325i is running rich

so i checked out
distr. cap + rotor
air filter
all OK

but I saw NGK ZGR5A spark plugs (well known on an M30)
are they ok for in an M20 ?
if not causing they a rich running engine ?



TIA Axl Cohen

[Jon '92 325ic]

Not sure about those spark plugs. I've only used Bosch oems myself. Most postings about spark plugs say the oems are best and to especially avoid the Bosch platinums.

Check your Bentley manual for troubleshooting a running rich problem. When my car was running rich (resulting in horrible fuel economy) it turned out my Oxygen Sensor. Bought a new one (BMA Autoparts had the best price) and problem solved.

[arsevader]

The first place to check when dealing with a rich running M20 is the coolant temp sensor (not the same as the gauge sender). It's found in the thermostat housing and can be blue or yellow. It has 2 prongs.

Check it according to the values found in the Bentley when hot and cold. Also check the same value at the ECU end of the harness to make sure that there is no break in the harness. This sensor is the main input for teh ECU to determine the correct fuel mixture.

Another thing to check is the throttle position switch under the throttle body.

You should also let us know if it is rich on start-up or when it's warm. The O2 sensor is ignored when the engine is cold so you can eliminate it at first.

James

[BavarianBimmer]

The first place to check when dealing with a rich running M20 is the coolant temp sensor (not the same as the gauge sender). It's found in the thermostat housing and can be blue or yellow. It has 2 prongs.

Check it according to the values found in the Bentley when hot and cold. Also check the same value at the ECU end of the harness to make sure that there is no break in the harness. This sensor is the main input for teh ECU to determine the correct fuel mixture.

Another thing to check is the throttle position switch under the throttle body.

You should also let us know if it is rich on start-up or when it's warm. The O2 sensor is ignored when the engine is cold so you can eliminate it at first.

James

It runs horrible when the engine is cold, the first 2-3 mins it smokes, doesn't even pull decent
When the engine is warmed up a 'bit it'll runs fine and not rich

so, I think the ECU coolant temp. sensor based on your comment :?

[arsevader]

It runs horrible when the engine is cold, the first 2-3 mins it smokes, doesn't even pull decent
When the engine is warmed up a 'bit it'll runs fine and not rich

so, I think the ECU coolant temp. sensor based on your comment :?

I'd bet money on it. As I said before, you should also check the harness. It is notorious for breaking at the sensor connector under the rubber boot.

James

[BavarianBimmer]

I'd bet money on it. As I said before, you should also check the harness. It is notorious for breaking at the sensor connector under the rubber boot.

James

Gonna check that tomorrow, thanks for the great help :-D

how do you mearsure if the wire it's broken?
I think measure the resistance through the ECU is a bad methode :?
On the pins from the ECU connector? If so wich pins ?

TIA Axel Cohen

[BavarianBimmer]

mission accomplished, was a bad contact on the coolant temp sensor

thanks for the help

[kowalski]

i really really really like your red 318....

[arsevader]

mission accomplished, was a bad contact on the coolant temp sensor

thanks for the help

Awsome. That's great.

James

[I_like_E30]

yep, mine was loose too! Just read this thread, went popped the hood, checked the sensor, and it runs very good now!!!