did you remember to plug the O2 sensors back in and get them around the right way. 2 usually connect by the fuel rail.
My fuel rail did not connect with o2 sensor. I removed my fuel rail once for injector cleaning a few months ago and there was no issue at that time. I just noticed I forgot to connect back the vacuum hose and will check the idle this morning. O2 sensor no signal is both upstream and downstream. Upstream voltage is 0.1 and down is 0.48 and those are fixed. No movement.
At 0.1V for the pre-cat O2's. You are either running extremely lean or they are both dead. Look at your wiring diagrams and check the O2 sensor wiring diagram fuses.
Wiring diagrams can been found in the "resources" section of this forum. See the blue ribbon at the top of your screen.
Wiring diagrams can been found in the "resources" section of this forum. See the blue ribbon at the top of your screen.
After I connected a vacuum hose, still same result. I noticed the MAF flow more air. Usually it is less 3g per second now it is 6-7g and if we open a throttle valve, it go up to 10-20g. I did not notice this before. The other thing is the crank shaft sensor fault. It happens sometimes but usually after warm up, we can clear it. I am going to check a huse of o2 sensor tonight.
I would appreciate any advice.
Regards
Kenya
I would appreciate any advice.
Regards
Kenya
Thanks for your advice. I was able to the z3 electrical trouble shooting manual and found the huse number 26 and 27. The huse looks ok. I also found a relay for o2 sensor needs to be checked but not sure where is it. The manual says it is in e-box. Where it is in my car?
Regards
Kenya
In the back of the wiring diagrams, there is a parts location list and some photos. Check in there.
Thanks! I found a location of E-box and also found two relay in my car while the manual has 3. Do you know where I can buy the relay? I checked the local bmw parts shop but they only sell one type of relay and not sure it is for o2 sensor.
OBD still shows a 0% STFT and upstream o2 sensor voltage remain at 0.1% and seems o2 sensor not working. O2 sensor replacement should be first before changing a relay ?
Regards
Kenya
Do you have a multi-meter or voltmeter?
Look at the wiring diagrams and see which pins in the relay base have the coil supply and the power supply for the contacts. With the key in position 2 and the engine off, check earth of these pins to earth (bare car metal) to confirm that there is 12 V. If either do not have 12V then you need to work back towards the power source until you find 12V.
Look at the wiring diagrams and see which pins in the relay base have the coil supply and the power supply for the contacts. With the key in position 2 and the engine off, check earth of these pins to earth (bare car metal) to confirm that there is 12 V. If either do not have 12V then you need to work back towards the power source until you find 12V.
I don’t have a voltmeter and need to buy it and learn how to use it. This morning, I checked OBD and found o2 sensor voltage started to change. The results is still low range (1.4 to 1.5) and I believe this should be replaced first. Hope a huse and relay is ok.
Can you advice your view?
Regards
Kenya
Can you advice your view?
Regards
Kenya
Your pre-Cat O2 sensor voltage should swing between around 0.1to 0.9 volts.
This is an update after O2 sensor replacement. LTFT is now +18% and STFT is +6% at idle after warm up. I guess the rich LTFT might be an injector leak.
I am going to investigate a lean condition as it is too height but now an Idle is stable.
A surprise at O2 sensor replacement was that there was no o2 sensor voltage after the installation. I was very shocked but I noticed the O2 sensor voltage started to swing from 0.1 to 0.9 after MAF sensor is off. Then, I reset ECM and drove a car with MAF on for a while and get the current Fuel trim data. Maybe the ECU needs some time to learn ?
Regards
Kenya
I am going to investigate a lean condition as it is too height but now an Idle is stable.
A surprise at O2 sensor replacement was that there was no o2 sensor voltage after the installation. I was very shocked but I noticed the O2 sensor voltage started to swing from 0.1 to 0.9 after MAF sensor is off. Then, I reset ECM and drove a car with MAF on for a while and get the current Fuel trim data. Maybe the ECU needs some time to learn ?
Regards
Kenya
- Joined
- Nov 25, 2012
- Points
- 178
- Location
- Newport, South Wales,UK
- Model of Z
- Z3 M43 1.8 (1999) and Z4 E85 2.5 (2003)
With the Maf sensor disconnected the car will revert to default settings from its default data in the ecu, if the car runs better with the Maf sensor disconnected then suspect a bad maf. If you reset the adaptions it may well be the car needs time to relearn its optimal settings, this could be over at least two drive cycles or a 100 miles.