R56 with low compression and possibly other problems

4959 Views 184 Replies 4 Participants Last post by kamilmarshal96, 10 d ago

karoliens

Discussion Starter · 11 mo ago

Hi,

Recently I have bought 2007 Mini Cooper S R56.
Previous owner said that it is burning a bit of oil and spark plugs need to be replaced. I have not had a chance to do full inspection on the spot so I took my chances.
I replaced air, fuel, cabin filters, engine oil and spark plugs that looked very bad (black and some of them had damaged ceramic insulator).
Then I decided to start with 'burning oil' issue by measuring cimpression.

Cold engine reading are as follows:
1-170psi
2-145psi
3-140psi
4-130psi

That does not look good... So what should be my next steps?
I am thinking to do leakdown test next and maybe do copression test when engine is warm.
Also it seems to be strange that starting from first cylinder compression is lowering in descending order. Maybe I should redo the test in the opposite order to rule out starter going weaker with every cylinder?

In addition I used OBD scanner to check for faults. None were found. Misfire counts are as follows:
1- evma min-1cnt max-0cnt
Last min-1cnt max-0cnt

2- evma min-2cnt max-0cnt
Last min-0cnt max-0cnt

3- evma min-0cnt max-0cnt
Last min-0cnt max-0cnt

4- evma min-1cnt max-0cnt
Last min-2cnt max-0cnt

What could I make out of this information?

Full engine rebuild or should I try something else?

Lastly there's a smell form the exaust but I can't figure out if is burning oil or unburnt fuel.

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mike1967

· #2 · 11 mo ago

looks to me like you battery is going weak if you tested from number 1 to number 4 ie the psi drops as you go through them, try recharge battery or maybe be do it with another vehicle and jump leads to ensure your not just seeing the battery get weaker with more load,

karoliens

Discussion Starter · #3 · 11 mo ago

mike1967 said:
looks to me like you battery is going weak if you tested from number 1 to number 4 ie the psi drops as you go through them, try recharge battery or maybe be do it with another vehicle and jump leads to ensure your not just seeing the battery get weaker with more load,

Thank you @mike1967! I will redo compression test with jump leads this weekend.
I have used Delphi DS150E to scan for fault codes and for system "Petrol" code 27AB has been returned. Description of the code is:

Fuel tank level
Intermittent

After bit of googling I found out that it might be related with MAP sensor? As I mentioned before I have replaced the air filter as well. Previously it was running Pipercross. Maybe that has something to do with issues I am having?

mike1967

· #4 · 11 mo ago

will ad that just because these engines have ok compression dont mean they are not burning oil as they have plastic oil rings that are all kinds of crap i change these when i rebuild them to solid 3 piece ring sets and cures that reason of oil use, i also pull head apart and clean and lap in valves and put better valve stem seals in ie i use elring really good only had good results from using them, why do you think its a map sensor fault

karoliens

Discussion Starter · #5 · 11 mo ago

mike1967 said:
will ad that just because these engines have ok compression dont mean they are not burning oil as they have plastic oil rings that are all kinds of crap i change these when i rebuild them to solid 3 piece ring sets and cures that reason of oil use, i also pull head apart and clean and lap in valves and put better valve stem seals in ie i use elring really good only had good results from using them, why do you think its a map sensor fault

The fault code 27AB is described as fuel level problem using ds150e, but I don't have any issues with fuel level.
Assuming this diagnostic tool has bad description or generic description of a fault I googled for fault 27AB and in BMW (Mini being BMW) forums found that it is related with MAP. Have you encountered fault 27AB and what could I make out of it. I think you are using same diagnostic tool - ds150e?

mike1967

· #6 · 11 mo ago

I see that code for bmw as ,,,,27AB Oxygen sensor adaptation at limit position before catalytic converter, bank 2 , so bank 2 is down stream 02 sensor, could be a number or reasons from if oil burning badly 02 sensor and cat are destroyed from it, might find by reset the adaptions with diagnostics tool ,,MUST DO THIS WHEN ENGINE IS COLD , reset it with diagnostics follow the on screen instruction's if using autocom i know autocom will reset adaptions on n14 engines and some n12 engines but not all,, might need something like a snap on diagnostics if it wont, then start car let it idle ontil fan cuts in and out then take for a drive for 20 minutes and you must some of the time use all the revs so ecu learns the fuelling's from 02 sensors , ds150e is autocom/delphi

karoliens

Discussion Starter · #7 · 11 mo ago

mike1967 said:
I see that code for bmw as ,,,,27AB Oxygen sensor adaptation at limit position before catalytic converter, bank 2 , so bank 2 is down stream 02 sensor, could be a number or reasons from if oil burning badly 02 sensor and cat are destroyed from it, might find by reset the adaptions with diagnostics tool ,,MUST DO THIS WHEN ENGINE IS COLD , reset it with diagnostics follow the on screen instruction's if using autocom i know autocom will reset adaptions on n14 engines and some n12 engines but not all,, might need something like a snap on diagnostics if it wont, then start car let it idle ontil fan cuts in and out then take for a drive for 20 minutes and you must some of the time use all the revs so ecu learns the fuelling's from 02 sensors , ds150e is autocom/delphi

I am using ds150e, but could not find option to reset adaptions within program.

mike1967

· #8 · 11 mo ago

so when connect to car get a side payne to the left on screen you should have 4 red square boxes top two for readings and reset fault codes,, the 3rd one should be cross tools looking that one select it, it takes you to a blank screen with a OK at top right and drop down box,, select the arrow on drop down box and it should give you options for resets , mine gives adaptions, and vanos adaption and battery register etc, if yours dont then its a cheaper single board scan tool and not full function ,,, if your car is using a lot oil then chances are the cat and 02 sensors are screwed anyway and reset adaptions wont make difference anyway, you could fit new cat and sensors but oil use will repeat the problem at some point,

karoliens

Discussion Starter · #9 · 11 mo ago (Edited)

Thank you for reply. As mentioned before I am not sure if the car is burning oil or running rich - there's a smell from the exhaust but no smoke and I can't distinguish between those two. I did a compression test again, this time using jump leads. Readings are as follows:
1cyl - 160psi
2cyl -160psi
3cyl - 160psi
4cyl - 145psi, after drop of oil - 160psi

Also I reset the adaptations and VANOS. The car lacks pull between 2000-3000rpm and also the smell.

Should I worry about 4cyl compression and draw a conclusion of bad rings? Is there any way to check O2 sensor? I was also thinking to test ignition coils?

Also I have not mentioned before because I was not sure if it is normal behaviour - when I turn the ignition on engine light comes on and stays but if I start the car it goes away.

mike1967

· #10 · 11 mo ago

it is always the gearbox end cylinder that gets most wear due to prolonged time and heat from that end of engine it seems,, have seen many break pistons due to lean outs on that cylinder from heat build up ,, question would be how many miles to litre of oil is it using

karoliens

Discussion Starter · #11 · 11 mo ago

mike1967 said:
it is always the gearbox end cylinder that gets most wear due to prolonged time and heat from that end of engine it seems,, have seen many break pistons due to lean outs on that cylinder from heat build up ,, question would be how many miles to litre of oil is it using

Personally I haven't noticed that oil level is decreasing. That was stated by the previous owner.

mike1967

· #12 · 11 mo ago

karoliens said:
Personally I haven't noticed that oil level is decreasing. That was stated by the previous owner.

I always take what a past owner tells me with a pinch of salt lol

karoliens

Discussion Starter · #13 · 11 mo ago

mike1967 said:
I always take what a past owner tells me with a pinch of salt lol

That is why I am trying to investigate what has made him draw this conclusion. I am checking the oil level constantly and have not noticed oil level to drop.

What is bothering me is that the smell from the exhaust and it drives sluggish.

Would you mind telling what else I could check with ds150e to find the some hints to solve these issues?

mike1967

· #14 · 11 mo ago

5

on live data you can male your own scan list , left payne square box with what looks like graph's
i put arrow in some shots to shot button to select

Product Font Screenshot Software Line

Product Font Screenshot Software Line

Light Rectangle Font Screenshot Line

Photograph White Light Product Black

Photograph White Light Product Black

by double clicking on left hand bar it will load that module test to right hand bar, when you have moved across all you want to see press the red button on right bottom ie 3rd one in,, then right after press the 2nd button so it brings the data up as numbers and not charts ,,
smooth running, misfire count , knock count, boost pressure actual and prescribed, vanos timings same again, fuel pressure at rail looking steady 5mpa idle and 8mpa under load north of 4000 revs on the road, can also add 02 sensor readings from signal looking for when engine hot and driving up road steady 3000 revs for a 0.7v switching slightly,, ie have 1,5 or 1v volt steady not changing then dead sensor or over fuel or under fuel, if over fuel its either last of boost or fuel problem 02 sensors or cat being dead can cause, so hard to write everything i go through when i get one like it as a lot depends on being next to it and gut feels at times,, the above test should set you on a path for either timing fueling or boost

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karoliens

Discussion Starter · #15 · 11 mo ago (Edited)

Thak you for advise @mike1967. I really appreciate it.

I have not had a chance to do a longer run and monitor the data but I checked the behaviour at idle with warm engine.

Fuel pressure @idle seems to be fine around 5mPa. What seemed to be off is voltage of pre-cat o2 sensor - it stayed around 1.5V @idle and dropped to 1.3v @2200rpm.

I have made a video of monitoring.

What would you think would be next step to do if pre-cat o2 readings are off? You mentuoned it could be many things.

mike1967

· #16 · 11 mo ago

think i would be checking timing chain first off, also the pcv pipe see if cracked letting in unmetered air, another one would the fuel tank vent pipe and solonoid at bottom of inlet manifold , would also pull the upstream 02 sensor out check colour if bright white its burning a fiar bit of oil,, if good chocolate brown grey,, if black and sooty running rich

karoliens

Discussion Starter · #17 · 11 mo ago (Edited)

3

Thanks I will do all these steps during the week. Now that you mentioned PCv system when I was replacing air filter I noticed that there's oil leak somewhere on the left side of the engine. I checked the diagram what's on that side and it seems there's PCV system and hose that connects to valve cover goes there as well. So I will remove the inlet manifold and inspect the PCV system.

Also I watched a video on how to remove inlet manifold and noticed that there should be air flow sensor on the tube that goes to air filter box and should unplug it if you want to remove whole airbox. I don't remember disconnevting anythin when I removed the airbox.

Video I watched was for N14 engine. Mine also has N14. So I am confused if the sensor was relocated in some models?

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mike1967

· #18 · 11 mo ago

that airflow pipe is fuel tank breather pipe it feeds to underside of inlet manifold is ecu controlled and is based on emissions it opens when car is on idle and adds the fuel tank pressure gasses to air intake ,, easy to remove has a single square button press in and away from the valve, yo also have a single 10mm bolt under the inlet manifold hidden from under the car by the wiring harness, I jack car up axle stands and look up above the driveshaft and to right of that fuel tank breather pipe you will see the 10mm,, i use 1/4 drive set,,,YOU MUST DISCONNECT BATTERY as can easy short starter with a socket, as for breather pipe they are genuine main dealer only around £50 uk money, i smoke test them these days as its possible to be cracked and leak,, cheap way is bung when end up pour some liquid in one end and wait for leaks,, that said after going to all that to remove it and they only last around 8 to10 years anyway might be worth just changing it and forget about it

karoliens

Discussion Starter · #19 · 11 mo ago

I've added some photos, that show there's no airflow sensor near airbox even though some videos show that there should be plug that I would need to disconnect. Second photo shows the area where valve cover and PCV hose is covered in oil and if I follow this hose down it is oil there as well but I can't see where the PCV line connects to. I nee to remove airbox and intake manifold first.

mike1967

· #20 · 11 mo ago

yep that pipe is buggered need new one that will make car run all to hell for sure, on your engine as its a turbo you have a map sensor under the airbox and one on the intake pipe above the engine mount, as yours is a turbo engine the 10mm bolt access is through the wheel arch area where track control arm is just above it

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