United Kingdom
Howdy all
I recently bought a Z4 and i have loved my ownership of it bar some strange gremlins that i cant track down.
I bought the car back in July 25, and was running like a Peach for about a week. One day i drove it a bit hard on the backroads and ever sense, some gremlins have appeared.
One, my coolant level light popped on straight after this, then turned off, then turned on, then off. And has been like this ever sense.
The resevoir is full, the temps are bang on in the middle where they should be. According to my OBD reader, 90 Degrees celcius. No spills in the gareg, my oil is as brown as it should be for the age, so milky residue in the oil at all. No back smoke out the back, bar the normal condensatiion when first warming up. Would this just be a faulty Coolant level sensor? or something more sinister.
Two, i have been chasing some strange misfires for some time now.
A few days after this, i noticed the ocassional thud when idling, and in the coming days it got worse, almost happening all times. Accekertation became very jerky, and next to no power. Rans the codes and was coming up with a misfire on cylinder 5. So i did the normal things.
So from here, i decided to just take it to my mechanic and just get a proper diagnosis done. He checked all the continuity in the wiring for both the coil packs and the injectors, and there were no issues at all. He looked over the CCV system and couldnt see anything out the ordinary. So he detirmined it was a faulty ECU. Was so confident in his diagnosis that he didnt charge me for it, his agreement was, if it was the ECU, then he will charge me for his diagnosis, if not, he wont charge me at all, and he'll start testing else where.
From here, i bought a replacemnt ECU, sent off my old one to get all the data copied off. Installed said replacement ECU and..... Still misfiring. However i decided to just let it idle all the way to temp, just incase it had to "Relearn" things.
Once it was up to temp, nothing, it was running smooth as anything. I decided to run the codes again and now it was only coming back with a P0134, which is bad O2 sensor for Bank 1 i believe. So i took it out on thr road and it was driving perfectly, no more jerky accelleration, and just pure 6 cylinder goodness.
However when i Rev the car, on neutral, the exhaust note is pretty strange, it has small pops when revving up, and a few coming down. I would expect a few when coming down but not when revving up. I can record a video if needed, but it sounds a little like how a popcorn map would sound on a old Jetta/Gold/Bora. Still very quiet, but just sounds strange.
Could there be a hole somehwere in the exhaust that is causing this noise, and maybe throwing the O2 sensor off. Would this be a incomplete combustion cycle, and the fuel isnt burning correctly? Could the CCV system do with being replaced? could the VANOS need looking at and maybe refurbished? Mind you acceleration is still perfect across the whole rev range.
I do apologise for such a long post.
Any help would be great.
Many thanks
I recently bought a Z4 and i have loved my ownership of it bar some strange gremlins that i cant track down.
I bought the car back in July 25, and was running like a Peach for about a week. One day i drove it a bit hard on the backroads and ever sense, some gremlins have appeared.
One, my coolant level light popped on straight after this, then turned off, then turned on, then off. And has been like this ever sense.
The resevoir is full, the temps are bang on in the middle where they should be. According to my OBD reader, 90 Degrees celcius. No spills in the gareg, my oil is as brown as it should be for the age, so milky residue in the oil at all. No back smoke out the back, bar the normal condensatiion when first warming up. Would this just be a faulty Coolant level sensor? or something more sinister.
Two, i have been chasing some strange misfires for some time now.
A few days after this, i noticed the ocassional thud when idling, and in the coming days it got worse, almost happening all times. Accekertation became very jerky, and next to no power. Rans the codes and was coming up with a misfire on cylinder 5. So i did the normal things.
- Replaced Sparkplug (Was dated 2021 and looked new, but replaced with new one anyways)
- Checked Coil packs, swapped around, misfire didnt transfer (Also dated 2021, and all 6 looked new)
- Checked all injectors, all looked fine, swapped out Cylinder 5 injector and still nothing, still misfiring.
- Checked DISA Valve, has had a refurb at some point as it had the upgraded silver flip inside, and all o-rings looked fine.
So from here, i decided to just take it to my mechanic and just get a proper diagnosis done. He checked all the continuity in the wiring for both the coil packs and the injectors, and there were no issues at all. He looked over the CCV system and couldnt see anything out the ordinary. So he detirmined it was a faulty ECU. Was so confident in his diagnosis that he didnt charge me for it, his agreement was, if it was the ECU, then he will charge me for his diagnosis, if not, he wont charge me at all, and he'll start testing else where.
From here, i bought a replacemnt ECU, sent off my old one to get all the data copied off. Installed said replacement ECU and..... Still misfiring. However i decided to just let it idle all the way to temp, just incase it had to "Relearn" things.
Once it was up to temp, nothing, it was running smooth as anything. I decided to run the codes again and now it was only coming back with a P0134, which is bad O2 sensor for Bank 1 i believe. So i took it out on thr road and it was driving perfectly, no more jerky accelleration, and just pure 6 cylinder goodness.
However when i Rev the car, on neutral, the exhaust note is pretty strange, it has small pops when revving up, and a few coming down. I would expect a few when coming down but not when revving up. I can record a video if needed, but it sounds a little like how a popcorn map would sound on a old Jetta/Gold/Bora. Still very quiet, but just sounds strange.
Could there be a hole somehwere in the exhaust that is causing this noise, and maybe throwing the O2 sensor off. Would this be a incomplete combustion cycle, and the fuel isnt burning correctly? Could the CCV system do with being replaced? could the VANOS need looking at and maybe refurbished? Mind you acceleration is still perfect across the whole rev range.
I do apologise for such a long post.
Any help would be great.
Many thanks