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 Posted: Feb 8, 2021 07:19AM
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Yes, the cylinder with 50 psi may have a burnt valve...  

As for 'is it worth it'? - If you are able to perform the dis-assembly and assembly yourself, it may be worth it, provided the rest of the car is in reasonable condition and you want to keep driving the car. You will probably have to have a machine shop do the 'valve job' (check prices before you begin).

If you feel you have gotten your money's worth out of your 2004 R50 Cooper, 208k miles is a decent amount of mileage and can be a good time to retire the car.

Not sure whether you have the 5-speed or cvt automatic, but either transmission 'can' be temperamental. If you suspect the transmission is starting to act up - then I would reconsider investing any sizeable $$ to keeping the car running...

 Posted: Feb 6, 2021 07:14PM
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rebuild meaning head job only, probably.

Then again, the car has 208,000 miles. Is it cost effective to do a head job?

 Posted: Feb 6, 2021 11:36AM
 Edited:  Feb 6, 2021 05:01PM
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I have never done a compression test on a newer car but on my mini my understanding is you should be within 10% of the highest number.  So with 190 you are almost within 10% at 170.  50 is a problem.  I suspect you are in for a rebuild on that 2004 MINI. Or at least a head job. Maybe ken will have better ideas but he is gone until Monday.

 Posted: Feb 6, 2021 10:10AM
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I performed a compression test and cylinder 4 has significantly lower pressure than the other 3. Here's what I got with a warm engine:
dry compression test
Cyl 1 - 190
Cyl 2 - 170
Cyl 3 - 170
Cyl 4 - 50
wet compression test
Cyl 1 - 270
Cyl 2 - 170
Cyl 3 - 210
Cyl 4 - 50

I cranked it about 6 times for each cylinder. With the wet compression test, I also noticed some smoke coming out of the empty cylinders as I performed the test, not sure if this is normal.

Any thoughts on how to interpret these results? Next steps? Thanks for the help!

 Posted: Feb 6, 2021 08:19AM
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Hi, I had not done a compression test or leak down test, so I purchased a compression tester and tried last night. Battery died half way through and it was getting dark, so I packed up and will try to repeat the test today. However, I did notice quite a bit of carbon build up on all 4 spark plugs (spark plug photo). I replaced them a little over a year ago (about 10,000 miles). Does this point to anything? Also, should I replace them again? I used NGK (3199) BKR6EQUP last time. Should I use different ones?

And no, no secondary air pump or air system valve, I haven't made any modifications to the car, just regular maintenance.

 Posted: Jan 30, 2021 07:22PM
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ALWAYS CYLINDER 4

FUEL: you have swapped the injectors and the problem did not follow the injector

SPARK: you seemingly have eliminated wires, plugs, coil pack from the picture

other than a computer issue, how about compression and leak down tests especially for cylinder 4.  
get the basics out of the way even if you do not think it is the answer.

Does this car have secondary air pump and air system valve and if so is it connected to cylinder 4?
I had cylinder 4 misfire codes on a 4 cylinder BMW/VW engine and the valve was the problem.
Some people say it should not have caused the issue (it is on the exhaust side) but it did.

 Posted: Jan 30, 2021 05:41PM
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Hi everyone, I tried swapping fuel injectors 3 and 4 today to see if the misfire would move from cylinder 4 to 3, but it did not. I am still getting codes P0304 and P2097. Is there anything else I can try? Thank you!

 Posted: Jul 10, 2020 05:22PM
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Thanks for the feedback! I finally replaced both O2 sensors with NTK sensors. According to the Carfax, neither sensor had been replaced before. The post-cat one actually looked okay, but I found that the pre-cat sensor's wire harness had chaffed through and conductors were exposed, so hopefully this was the problem. I think the car is idling higher than it was before (used to idle below 1000, but now is just above it). However, it is still throwing the P2097 code. Does anyone know if this will clear by itself over time (if so, how long?) or do I need to take it to a dealership?

There's mixed comments online about having to reset fuel trim adaptive values and if it's even possible to do it without a computer/BMW tool.

I did borrow a Foxwell NT510 Elite to clear the codes and used it to read the short term and long term fuel trim values. The system is in closed loop, and the short term reads between -3% and -10% between idle and 3000 RPM, while the long term reads between (positive) 3% and 5%. From what I was able to read about expected values, these are probably okay for a car with this many miles, but if anyone has any insight, let me know! 

One last comment, although it is idling higher, I let it sit there for a while and it eventually struggled and threw a P0304 (cyl 4 misfire) again. I cleared it and it hasn't happened again yet, but it's only been a few days. When it was idling below 1000 before I replaced the O2 sensors, this would happen almost immediately if I let it sit at idle. Thanks again for any help!

 Posted: Apr 2, 2020 10:06AM
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Let us know what you find!

 Posted: Apr 1, 2020 04:36PM
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I would suggest looking at some youtube videos on long term and short term fuel trim. It helps to understand more how O2 sensors and your ECU works. I hope this helps resolve your issues.

 Posted: Mar 17, 2020 02:46AM
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Quote:
Originally Posted by rodolfo2110
I haven't had a chance to try replacing the O2 sensors, but I ran the scanner again and noticed that I am also getting a P0136 code (Oxygen Sensor Circuit Low Voltage - Bank 1 Sensor 2) in addition to the P2097. Does this help narrow down my issue? Thanks again!
Have you tried swapping the o2 sensors? You may have a defective sensor or maybe the catalytic converter has gone bad....

 Posted: Mar 15, 2020 12:11PM
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I haven't had a chance to try replacing the O2 sensors, but I ran the scanner again and noticed that I am also getting a P0136 code (Oxygen Sensor Circuit Low Voltage - Bank 1 Sensor 2) in addition to the P2097. Does this help narrow down my issue? Thanks again!

 Posted: Jan 27, 2020 09:06AM
 Edited:  Jan 27, 2020 10:35AM
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Understood, but what could cause both sensors to go out of range (they drop to almost 0V) at idle? Also, once they drop to 0V, they stay there until I restart the car, then they return to the normal range (.1V to 1V). Thanks again.

 Posted: Jan 27, 2020 06:42AM
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Quote:
Originally Posted by rodolfo2110
I borrowed a Foxwell NT510 to read the values of the O2 sensors and see if they were working correctly. Before starting the engine, both sensors slowly increased to about .42V. I then started the engine and started driving. Sensor 1 fluctuates between .1V and .8V, and sensor 2 was pretty steady around .8V. Car seemed to be running fine (despite check engine light being on). Then I came to a stop sign and slowed down. As soon as I came to a full stop, both sensors dropped to .01V, the check engine light started flashing, and the engine started running rough. The sensor voltages never rose after that even after I accelerated. However, if I turn off the car and start it back up, the sensors go back to working as listed above. Any thoughts on what could be causing this drop to 0V for both sensors at idle?
Normal operating range for both o2 sensor signal is between 0.1v and 1.0v. The heater circuit goes higher but not the signals.

 Posted: Jan 23, 2020 10:20AM
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I borrowed a Foxwell NT510 to read the values of the O2 sensors and see if they were working correctly. Before starting the engine, both sensors slowly increased to about .42V. I then started the engine and started driving. Sensor 1 fluctuates between .1V and .8V, and sensor 2 was pretty steady around .8V. Car seemed to be running fine (despite check engine light being on). Then I came to a stop sign and slowed down. As soon as I came to a full stop, both sensors dropped to .01V, the check engine light started flashing, and the engine started running rough. The sensor voltages never rose after that even after I accelerated. However, if I turn off the car and start it back up, the sensors go back to working as listed above. Any thoughts on what could be causing this drop to 0V for both sensors at idle?

 Posted: Nov 14, 2019 11:06AM
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The pre and post sensors are the same units - you might try swapping the two to see if the errors change.

 Posted: Nov 14, 2019 09:00AM
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No, the cat and O2 sensors have never been replaced. Is there a way to check if that's the issue though? I read one thread that replaced the post O2 sensor and resolved his issue, but I also read quite a few more threads where they tried that and still had the same code. And thanks! I hope to keep it running for quite a few more thousand miles!

 Posted: Nov 14, 2019 04:08AM
 Edited:  Jul 13, 2020 07:06AM
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Here are some error code definitions:

P2097 - Post Catalyst Fuel Trim System too rich (Bank 1)
P0304 - Cylinder 4 Misfire Detected
P0313 - Misfire detected with low fuel

Given the high mileage on your MINI (congrats on getting over 200k!), the first thing I would question is the condition of the catalytic converter and the o2 sensors before and after the cat. Has the cat or the sensors ever been replaced?

 Posted: Nov 13, 2019 02:37PM
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Not sure if it's related, but the constant mpg on the display was stuck at 99.9 for a while, which led me to believe that I was actually getting better gas mileage with Techron. I recently filled up the tank again though, and it hasn't stuck since. I tried to see if this ever happened to anyone else, but haven't found anything yet. Thanks again for any advice!

 Posted: Nov 13, 2019 09:09AM
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Hi everyone, I drive a 2004 Mini R50 w/ auto transmission (208,000 mi), and I started getting a check engine light with P2097 code in the summer. The first couple of times I was able to clear it, but now it comes back right away. I didn't notice any kind of performance loss or mpg drop, so I didn't think much of it. Now that it's fall and I am no longer running the AC, I started noticing RPM loss at idle. If it sits long enough, the engine light will blink and it'll throw a P0304 (cyl 4 misfire) code, but as soon as I start driving again it runs fine. Once I also got a P0313 code, but never since.

I replaced all spark plugs and wires, and swapped in a new coil pack. I replaced the air filter and ran Techron fuel system cleaner through the tank. I also reset the ECU and the BCU. But nothing has helped so far. Has anyone run across this before? If you can point me to an existing thread or share what else I should try, I would really appreciate it! Thanks in advance!