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Discussion Starter · #1 ·
Hi All

First post, so go easy... :)

I have an R56 Mini with the N12 1.4 petrol engine (Non Turbo) with 70000 miles, that has developed a misfire. It's starts off running not too bad from cold, but gets worse quickly as it warms up when the idle revs drop. After a minute or two from cold start the engine noise seems to change and get a little noisier, the revs then seem to 'hunt' up and down, and the odd misfire begins to occur - not regular but often.

Oil is clean and at the correct level.

I have a decent fault reader (Autel MaxiPRO) which has returned three fault codes:

2A98 Digital Motor Electronics (DME), catalytic converter upstream oxygen sensor, sensor lines - Absent

2B15 Digital Motor Electornics (DME), differential pressure, intake manifold, plausibility - Present

2B67 Digital Motor Electronics (DME), Mass Air Flow (MAF), plausibility - Absent

I can clear the codes, but they will eventually return.

Looking at the live data I can see that most of the misfires occur in cylinder 1, with one or two occurring in other cylinders.

I invested in an articulating borescope camera (excellent piece of kit) to take a look at the valves and see if I could spot anything obvious.

The video below is cylinder 1 (presuming cylinder 1 is driver side on RHD car):

Does the exhaust valve seat look damaged, burnt, coked up to the extent that it might be causing the problems above?

Any other suggestions as to what might be causing the problem? I don't want to lead you with the video as this might not be the core issue, I know these engines have issues with stretched timing chains, broken guides, worn Vanos systems. If I can replace a simple sensor instead of removing the head/chain etc. it would obviously be preferable. Any comments/advice welcome.

(1) Mini N12 Misfire on Cylinder 1 - YouTube
 

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yep its burning oil badly common issues below link worth a read explains all without me spending a hour or two typing
its not if this happens its always when and they all go this way
 

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Discussion Starter · #3 ·
Thanks Mike, Looks like I'll be tearing it apart then.

Whereabouts are you, I take it you're no where near Edinburgh?

What causes this? Is due to a stretched timing chain/retarded timing, or because they suck up their own crank case oil via the PCV, or because the stem seals harden wear and leak, or because the rings wear? It has relatively low mileage at 70,000, do you really think the rings will be worn?

I was thinking about just testing how much the tensioner has remaining (I take it you used a white paint pen mark, then re-insert to test how much scrapes off), and if the chain isn't too bad then try to chemically clean the valve seats by soaking in valve cleaner + brake cleaner, or Seafoam via the exhaust ports. Wishful thinking?

Got too many projects on at the moment, looking for an easy fix that probably doesn't exist (as usual).
 

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70k chain will be done , its a number of things cause it , when add them together it has no chance,
1. these engines run hot by design for low emissions, this thins oil and hurts the rubber ie stem seals,
2 the run so hot that run more lean this causes hotter combustion temps,
3 timing chain stretches by as low as 30k by 60k its done and some people dont know they drive on and on until get misfires or many the chain snaps or slips teeth ,
4 this happens more than you would think, someone buys a brand new mini and wrongly thinks that because its new it wont use oil or cant be bothered to check oil and they run car low or out of oil, even knew a few people that thought when red oil can light comes on the dash its then time to drive to garage and get oil,,,
5 the stupid 24 month or 20k oil change bmw say is when they need service,, na 12 months 8k in my book
6 bmw use really bad oil control rings on the pistons ,, i do away with these single piece flexi rings and fit 3 piece rings sets sorts out a lot of oil use ,
i'm down in cornwall miles a away ,
if i were in shoes head off all valves out and sort head would also pull the piston hone bores and rering it ,,
first job is oil pressure test when car is at 105c temps ie running temp ,, must see 1.5bar idle 3,0bar 3000 revs is ref point,
 

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Discussion Starter · #5 ·
Might have guessed you'd be at the other end of the country, I would have snapped your hand off for £850 to avoid the hassle. There's no substitute for experience wit these things, and it looks like you've been down this road once or twice before.

One question, you stated that cylinder 1 is at the gearbox side. That's at the right side of the engine when you are standing in front of the car looking into the engine bay, right?

Ok, two questions then.. is it an engine out Jobbie, or can you drop the sump and take the pistons out the bottom with the subframe still in place?
 

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Might have guessed you'd be at the other end of the country, I would have snapped your hand off for £850 to avoid the hassle. There's no substitute for experience wit these things, and it looks like you've been down this road once or twice before.

One question, you stated that cylinder 1 is at the gearbox side. That's at the right side of the engine when you are standing in front of the car looking into the engine bay, right?

Ok, two questions then.. is it an engine out Jobbie, or can you drop the sump and take the pistons out the bottom with the subframe still in place?
number 1 gearbox end its a psa hand me down, must admit i do a fair few of them for garages mainly on trade terms.
no need to pull engine as long as got good oil pressure and crank bearings all look silver still,, i do them engine in as long as got good oil pressure and have checked the furthest crank big end journal from oil pump as that seems to get most wear if any, as for taking engine out always leave subframe in pull front off car only takes a couple of hours the first time, will need to regas aircon when put back together
 

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I guess there's always this option:

BMW Mini One 1.4 Petrol Engine 55,514 Miles (R55/R56/R57 2007-2010) N12B14 | eBay

will probably end up with the same issues in 15 - 20k miles, but at least it might get me back on the road with reduced hassle.
yep sure will if not already at that point i have done many under 50k over the years , i've also done many vag petrol engines with same sort of issues seems it is the way its all gone , ie run a engine so hot its nearly leaning out to gain better mpg at cost of the life of engine,, ie if life of engine is 50-80k then i guess
 

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Discussion Starter · #9 ·
number 1 gearbox end its a psa hand me down, must admit i do a fair few of them for garages mainly on trade terms.
no need to pull engine as long as got good oil pressure and crank bearings all look silver still,, i do them engine in as long as got good oil pressure and have checked the furthest crank big end journal from oil pump as that seems to get most wear if any, as for taking engine out always leave subframe in pull front off car only takes a couple of hours the first time, will need to regas aircon when put back together
I've had the front end off one or two R50/53's in my time, so presume the process is similar for the 56. I've also got a/c re-gas kit so no issues there. I guess if it's easy enough might as well re-ring and check the journals whilst I'm in there. Will check the oil pressure first though as per your previous post. Appreciate the parts and tool links you put in your previous posts, will keep these close to hand as they are invaluable. Kudos to you for the selfless approach, especially since it's your trade.
 

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Discussion Starter · #10 ·
yep sure will if not already at that point i have done many under 50k over the years , i've also done many vag petrol engines with same sort of issues seems it is the way its all gone , ie run a engine so hot its nearly leaning out to gain better mpg at cost of the life of engine,, ie if life of engine is 50-80k then i guess
Yep, it's all very cleverly designed to milk the consumer of all of their hard earned cash these days. Needless to say, my daily drive is a 1992 Mk3 Hilux Pickup... no such issues there

Top man Mike, thanks for all of the advice. You've saved me some pain here.

Cheers
 

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I've had the front end off one or two R50/53's in my time, so presume the process is similar for the 56. I've also got a/c re-gas kit so no issues there. I guess if it's easy enough might as well re-ring and check the journals whilst I'm in there. Will check the oil pressure first though as per your previous post. Appreciate the parts and tool links you put in your previous posts, will keep these close to hand as they are invaluable. Kudos to you for the selfless approach, especially since it's your trade.
i've never like how some trade people hide info or give just enough to cause someone trouble in some kind of hope of getting work back off I guess , it dont cost me anything to help someone , I got more work and jobs than I know what to with myself most of the time
 

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Yep, it's all very cleverly designed to milk the consumer of all of their hard earned cash these days. Needless to say, my daily drive is a 1992 Mk3 Hilux Pickup... no such issues there

Top man Mike, thanks for all of the advice. You've saved me some pain here.

Cheers
back in 1990 i worked for a garage and all we would do is buy rusty hylux's and weld them up and paint them and sell them again rarely ever had a engine failed one back in the days when things were made ,, i had loads of bmw 325tds e36 cars never went wrong nothing like the rubbish bmw build today is it
 

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Discussion Starter · #13 ·
back in 1990 i worked for a garage and all we would do is buy rusty hylux's and weld them up and paint them and sell them again rarely ever had a engine failed one back in the days when things were made ,, i had loads of bmw 325tds e36 cars never went wrong nothing like the rubbish bmw build today is it
Yeh, the old 3 series tds. I had a 318 tds, couldn't pull the skin off a rice pudding but never went wrong :) The only BMW exception today, well I say today.. thinking about it my 535d M sport is now 17 years old! But the M57 engine was/is bullet proof, beyond a few daft daft ancillary ideas like swirl flaps, dodgy throttle bodies, EGR, and DPF regen prerequisites which eventually choke and kill them.

Like anything else, if properly maintained they'll last fine.
 

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that 535tds early engines were epic in my book the newer ones have gone down the n47 diesel route and put chain at rear and tiny thin crap one at that , i do a lot stuff for mapping company where they have a car for remap rolling road and on their pre checks find issues on engines they tend to throw them my way , very very common all car markers after 2005 have chain issues on all of it EU built spanks of some kind of agreement to build same week parts to me and the customer has nowhere to hide , same EGR and DPF both cause so much damage to all engines and barely get to 100k before being screwed by the carbon that before all this was pushed out the engine, where now the engine and inlet is fair game to collect it so they can get a low emissions stamp of approval and get through gas checks in my book,, ironically a dpf only really works for first 10k if that after that it causes more soots and increases loss power to the gallon so more fuel gets burnt, really is endless cars with such faults ,, take the new landrovers they have mounted the dpf filter half way back under the floor so dont get hot enough to regen the filter and when does after big miles and heavy foot causes wash by on pistons ie when in regen mode for to long it loads the engine oil with diesel knocks out the crank,, put in spares repairs landrover and rangerovers all the 3.0 diesels and all have engine failure do to it,, worst part its body off to change the engine, or cut away the inner and out wing on one side its possible to do it as well,
 

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added note i have for past 15 years only kept any car under 4 months,, law of numbers play pass the parcel narrow chances of having major failure also i only but one thats already broke ,, funny before i done this i was wasting thousands on cars and now i sort make a few quid on one spend on another but always come out on top in the end ,,
 

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Discussion Starter · #16 ·
that 535tds early engines were epic in my book the newer ones have gone down the n47 diesel route and put chain at rear and tiny thin crap one at that , i do a lot stuff for mapping company where they have a car for remap rolling road and on their pre checks find issues on engines they tend to throw them my way , very very common all car markers after 2005 have chain issues on all of it EU built spanks of some kind of agreement to build same week parts to me and the customer has nowhere to hide , same EGR and DPF both cause so much damage to all engines and barely get to 100k before being screwed by the carbon that before all this was pushed out the engine, where now the engine and inlet is fair game to collect it so they can get a low emissions stamp of approval and get through gas checks in my book,, ironically a dpf only really works for first 10k if that after that it causes more soots and increases loss power to the gallon so more fuel gets burnt, really is endless cars with such faults ,, take the new landrovers they have mounted the dpf filter half way back under the floor so dont get hot enough to regen the filter and when does after big miles and heavy foot causes wash by on pistons ie when in regen mode for to long it loads the engine oil with diesel knocks out the crank,, put in spares repairs landrover and rangerovers all the 3.0 diesels and all have engine failure do to it,, worst part its body off to change the engine, or cut away the inner and out wing on one side its possible to do it as well,
I'm regularly tempted by Land rovers, they're such good looking cars. Suspension issues, engine issues, turbo issues just make them too big a risk for me. Think the Range rover can do engine and turbos with body on, but Disco needs body off for most work. Think you can just about squeeze the turbos with body on though.

Emission laws drive most of the detrimental stuff with cars nowadays, and to an extent I can see it from the manufacturers point of view. They must spend billions on innovation just to make their cars compliant, knowing that at the end of the day it will make them fail sooner. That said, it's all extra business for them and you when it does fail.

I'll stick to my Hilux for now, they'll eventually have to prize the keys out of my cold dead hands...

Wheel Tire Automotive parking light Automotive side marker light Land vehicle
 

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Discussion Starter · #17 ·
Ok, got my feet reasonably clear so about to start buying parts for this

Courtesy of Mike 1967's recommendations...

Chain/Head kit Sorted
Piston Rings Sorted
Ring Installer Sorted
Bore Hone Tool Sorted

Any recommendations on a cam lock tool?
 

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Ok, got my feet reasonably clear so about to start buying parts for this

Courtesy of Mike 1967's recommendations...

Chain/Head kit Sorted
Piston Rings Sorted
Ring Installer Sorted
Bore Hone Tool Sorted

Any recommendations on a cam lock tool?
this is a painful one laser tools and not cheap, i got a draper one that was £199 5 years ago , most cheap china tools not good , got one my self i compared it to the draper on a engine and found was slightly out i do take up the slack by using a feeler gauge on the surface where the lock tool locates to camshaft so they are tight and was well with in 1 degree where before was more 4 degrees between the two camshafts,,,
 

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Discussion Starter · #19 ·
this is a painful one laser tools and not cheap, i got a draper one that was £199 5 years ago , most cheap china tools not good , got one my self i compared it to the draper on a engine and found was slightly out i do take up the slack by using a feeler gauge on the surface where the lock tool locates to camshaft so they are tight and was well with in 1 degree where before was more 4 degrees between the two camshafts,,,
Do you have a part number for the Draper tool?
 
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