- This topic has 8 replies, 4 voices, and was last updated 10 years, 7 months ago by
.
-
Topic
-
Hello to all,
I did this video today:
https://www.youtube.com/watch?v=rm7qKPMqLpw&feature=youtu.be
The car is a not properly maintained 1995 BMW Z3 with 1.9L 4 cylinder engine. This is my first car that I have got a few months ago. I am new to DIY car repairs and very enthusiastic about it.
The engine and exhaust does not sound smooth for me and feel lots of uneven vibrations inside the car. Some folks have suggested the car is suffering from a cylinder misfire. I tried to unplug ignition wires one by one and got zapped on cylinder#4. Should I get a new wire set and spark plug boots and move on to the compression test?
Spark plugs, fuel filter, oil filter, air filter, battery are all brand new made by Bosch and installed 500 km ago. $8 OBD2 scanner throws a O2 sensor circuit malfunction (getting a new one this week).
Any thoughts ?
-
Replies
-
The code is for an O2 circuit malfunction. It could be a bad O2 but it could also be an issue with wiring or a connector. I suppose we’ll find out after you replace it. Your exhaust sounded like you might have a miss. Your power balance test was inclusive in my opinion but it might be worth checking the compression on that engine to see what kind of shape it’s in. If you have a mechanical issue you need to address that first. More info here.
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
Good luck and keep us posted.
Wednesday – I’ve got a spark plug wrench and took two spark plugs out and cleaned them. They both were oily as the first two in the picture.
Friday – I did 60 miles since Wednesday. Installed new spark plug wires/boots and o2 sensor. There were no oil on spark plug boots and only old traces of oil in spark plug wells. The engine seems to respond better while driving like crazy and smoother when idling or it’s just a placebo effect after paying $250 for these 2 parts 🙂
Saturday – I tried to change the valve cover gasket and made these photos. The old gasket looked all right without any obvious cracks and was very easy to remove. I have cleaned spark plug wells and spark plugs and put it back together, doing some testing tomorrow.
Since spark plug wells and wire boots are clean, does it mean the oil gets from somewhere else due to a cracked head gasket?
I got booked for a compression test.
Please tell me what you think by looking at these images and “reading” spark plugs
The first two are covered in oil that’s sticky and somewhat heavier than a normal oil found on the 3rd and 4th.
Is it cover supposed to look like this on the inside? I mean these black dirty areas in between spark plug holes look like a layer of carbon.
I have replaced the valve cover gasket last Sunday and 4 days after the sparks are clean (I did 100 miles since then).
Today I went to a car repair shop nearby and asked for a compression. The results are: 13.5 / 14 / 13.5 / 13.8
What does it say? Guys at the repair shop say the engine compression is fine and I should perhaps clean fuel injectors.
The inside of your engine looks like it hasn’t seen enough oil changes. That’s not the end of the world but it can cause issues with oil seals as it makes them harden up and leak. This is probably the reason you had oil leaks into the plug wells. Now that you’ve replaced those seals you should be fine. You might consider switching to a high mileage oil as they have seal conditioners to deal with issues like yours. It may help prevent leaks in the future. As for solving performance problems or idle issues, I recommend you read through these.
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
http://www.ericthecarguy.com/faq/solving-automotive-idle-problems
Jonas, you might want to check the catalytic converter and exhaust system as well. This sounds somewhat similar to my son’s Chevy Cavalier a while back with a bad converter. Additionally, the restriction was causing misfires. It even caused a secondary vibration in the vehicle. We did a simple shaking of the exhaust near the converter when it was cool and could hear it rattling. Just something else to consider. This too could affect the 02 sensor.
- You must be logged in to reply to this topic.