N12 Engine issues
#1
06-21-2018, 08:58 AM
N12 Engine issues
I cross-posted this from the R55 Clubman forum, since there seems to be more traffic here and the issue isn't specific to the Clubbie.
https://www.northamericanmotoring.co...-problems.html
tl;dr: I changed out the valve cover gasket and spark plugs. Car ran fine previously, but it now misfires at idle and throws P0300 code when the MAF is plugged in. Runs smoothly when the MAF is unplugged and obviously throws a MAF code (no misfires). Have replaced MAF and coils with no change. I'm now stumped as to where to look next.
https://www.northamericanmotoring.co...-problems.html
tl;dr: I changed out the valve cover gasket and spark plugs. Car ran fine previously, but it now misfires at idle and throws P0300 code when the MAF is plugged in. Runs smoothly when the MAF is unplugged and obviously throws a MAF code (no misfires). Have replaced MAF and coils with no change. I'm now stumped as to where to look next.
Hi all,
A few weeks ago, we took possession of a 2010 Justa Clubman 6-speed from some friends of my cousin. It's my cousin's car, and we're holding it onto it for their daughter for next year (great parents, huh?)
The car has 84,000 miles on it, and we put about 2-300 miles on it between taking delivery, running errands, and my wife took it to work for a few days. During that time, being the car guy that I am, I began to take stock of whatever the car's needs were. First of which, was a leaking valve cover gasket. The gasket was leaking oil out the sides, but also into the #1 cylinder plug well. Amazingly, the car ran fine, and there was a little but not much oil contamination on the coil.
So, during our weekly get-together, my car buddies and I descended upon the Mini, determined to change out the valve cover gasket. I'll preface by saying we know our way around various Euro cars (BMW and VW/Audi mostly) so it wasn't outside of our wheelhouse to change out a valve cover gasket.
Armed with a new Ajusa valve cover gasket and NGK spark plugs, we got the gasket and plugs changed out. I elected not to change out the coils as the car was running fine before. When I started it up the next morning, it was idling a bit rough, but ran fine off idle, so I didn't think much of it at the time. All was well until about 20 miles into my drive to work, the car started misfiring and stalled on me. I got it towed back home to figure out what went wrong.
The codes I got were P0300 Random Misfire and P0303 Cylinder #3 misfire. FYI - The coil I had noted before that was lightly contaminated was the #1 cylinder.
Meanwhile, my parts guy at FCP realized they had some bad fitment data from a vendor on the plugs I ordered, and that the NGK's were not the right ones (despite being the right size/thread). So, armed with the right plugs (Beru 12ZR6SP03) I fired it up, and it was still misfiring. It took a while for the code to come up, but eventually it threw a P0300 Random Misfire code. I unplugged the MAF sensor, and everything smoothed out. Cleared codes, and obviously the CEL pops up for a missing MAF, but otherwise, it runs a lot better.
Regardless, on the off chance thinking it may be the contaminated coils, or a MAF - I got both a new MAF and new set of coils to try out (both Bosch). I finally got those in last night, and it is still the same - misfires, P0300 code, and when you unplug the MAF it runs smooth. We noticed short term fuel trims were maxed at +25%. Plugs had some soot and smelled like gas, like it was running rich. Unplugging the MAF makes those go back closer to zero.
Compared some at-rest values for the new MAF and old MAF and they're equal - about 0.1 lb/min at rest.
With the STFT's maxed out, we decided to do a battery reset. Once we got everything back together, fired it up and it misfires and then dies. STFT's are zero because I can't keep it running long enough to get enough fuel in there to keep it running.
What is going on here? Despite our experience, we don't have a lot of wrench time on these Mini engines, but I didn't think they'd be this sensitive to a valve cover gasket change. Is this how the engine reacts to a big vacuum leak?
Last night we looked at the items we removed to replace the valve cover gasket. The intake boot didn't have any splits in it. The PCV hose looks okay, but we only disconnected it from the valve cover, not the bowels of the motor. I didn't notice any cracks in the valve cover itself. I hate to be throwing parts at it, but I'm reaching the point where we need to get it back on the road.
We're stumped, which is why I finally signed up and came over to b*tch to you guys. Any ideas?
Here's the sick Clubbie:
A few weeks ago, we took possession of a 2010 Justa Clubman 6-speed from some friends of my cousin. It's my cousin's car, and we're holding it onto it for their daughter for next year (great parents, huh?)
The car has 84,000 miles on it, and we put about 2-300 miles on it between taking delivery, running errands, and my wife took it to work for a few days. During that time, being the car guy that I am, I began to take stock of whatever the car's needs were. First of which, was a leaking valve cover gasket. The gasket was leaking oil out the sides, but also into the #1 cylinder plug well. Amazingly, the car ran fine, and there was a little but not much oil contamination on the coil.
So, during our weekly get-together, my car buddies and I descended upon the Mini, determined to change out the valve cover gasket. I'll preface by saying we know our way around various Euro cars (BMW and VW/Audi mostly) so it wasn't outside of our wheelhouse to change out a valve cover gasket.
Armed with a new Ajusa valve cover gasket and NGK spark plugs, we got the gasket and plugs changed out. I elected not to change out the coils as the car was running fine before. When I started it up the next morning, it was idling a bit rough, but ran fine off idle, so I didn't think much of it at the time. All was well until about 20 miles into my drive to work, the car started misfiring and stalled on me. I got it towed back home to figure out what went wrong.
The codes I got were P0300 Random Misfire and P0303 Cylinder #3 misfire. FYI - The coil I had noted before that was lightly contaminated was the #1 cylinder.
Meanwhile, my parts guy at FCP realized they had some bad fitment data from a vendor on the plugs I ordered, and that the NGK's were not the right ones (despite being the right size/thread). So, armed with the right plugs (Beru 12ZR6SP03) I fired it up, and it was still misfiring. It took a while for the code to come up, but eventually it threw a P0300 Random Misfire code. I unplugged the MAF sensor, and everything smoothed out. Cleared codes, and obviously the CEL pops up for a missing MAF, but otherwise, it runs a lot better.
Regardless, on the off chance thinking it may be the contaminated coils, or a MAF - I got both a new MAF and new set of coils to try out (both Bosch). I finally got those in last night, and it is still the same - misfires, P0300 code, and when you unplug the MAF it runs smooth. We noticed short term fuel trims were maxed at +25%. Plugs had some soot and smelled like gas, like it was running rich. Unplugging the MAF makes those go back closer to zero.
Compared some at-rest values for the new MAF and old MAF and they're equal - about 0.1 lb/min at rest.
With the STFT's maxed out, we decided to do a battery reset. Once we got everything back together, fired it up and it misfires and then dies. STFT's are zero because I can't keep it running long enough to get enough fuel in there to keep it running.
What is going on here? Despite our experience, we don't have a lot of wrench time on these Mini engines, but I didn't think they'd be this sensitive to a valve cover gasket change. Is this how the engine reacts to a big vacuum leak?
Last night we looked at the items we removed to replace the valve cover gasket. The intake boot didn't have any splits in it. The PCV hose looks okay, but we only disconnected it from the valve cover, not the bowels of the motor. I didn't notice any cracks in the valve cover itself. I hate to be throwing parts at it, but I'm reaching the point where we need to get it back on the road.
We're stumped, which is why I finally signed up and came over to b*tch to you guys. Any ideas?
Here's the sick Clubbie:
#2
06-21-2018, 09:04 AM
OVERDRIVE
#3
06-21-2018, 09:50 AM
I'm thinking maybe that might be it, but I'm also looking at any other possibilities before pulling the valve cover again. It is possible that the new gasket could have not seated properly, but I'm not seeing any external leaks from the valve cover - at least not compared to before I replaced the gasket.
As I mentioned, I'm just not familiar with Minis (yet) to know if there's something obvious that I'm missing.
Thanks for the reply
As I mentioned, I'm just not familiar with Minis (yet) to know if there's something obvious that I'm missing.
Thanks for the reply
#4
02-19-2019, 10:20 AM
2nd Gear
I'm thinking maybe that might be it, but I'm also looking at any other possibilities before pulling the valve cover again. It is possible that the new gasket could have not seated properly, but I'm not seeing any external leaks from the valve cover - at least not compared to before I replaced the gasket.
As I mentioned, I'm just not familiar with Minis (yet) to know if there's something obvious that I'm missing.
Thanks for the reply
As I mentioned, I'm just not familiar with Minis (yet) to know if there's something obvious that I'm missing.
Thanks for the reply
#5
02-19-2019, 10:59 AM
Also, part of the problem may have been the use of sealant on the corners near the half moon bosses on the head (as is common practice in other DOHC engines I’ve worked on). I found that out when I replaced the valve cover gasket for a second time (this time I got a Genuine Mini gasket) and put the sealant in and started it up, it still had a vacuum leak which caused it to run poorly. Removed the sealant, bolted it back on, and the car ran like it did when I first got it.
I suspect there is still a minor vacuum leak somewhere because the cold start idle is still a little rough, and it can be a little rough as the engine settles to idle - I can view the short term fuel trims changing as the engine smooths out.
But it’s all minor and is probably because I’m sensitive to it now. I also have no frame of reference from when the car was new, as it was bought new by a family member who now lives overseas. The car runs fine enough as it is, and I’m enjoying the occasional drive, as well as preparing it to pass along to their daughter (including teaching her to drive manual!). The valve cover gasket no longer leaks so it is for all intents and purposes fixed!
The following users liked this post:
rondayvous (02-20-2019)
#6
02-20-2019, 04:22 AM
2nd Gear
Also, part of the problem may have been the use of sealant on the corners near the half moon bosses on the head (as is common practice in other DOHC engines I’ve worked on). I found that out when I replaced the valve cover gasket for a second time (this time I got a Genuine Mini gasket) and put the sealant in and started it up, it still had a vacuum leak which caused it to run poorly. Removed the sealant, bolted it back on, and the car ran like it did when I first got it.
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