Hey guys, my wife's 2010 R56 (base model, ~60K miles) suddenly started running very rough, both while idling and driving. I pulled the codes: P0300 and P0304. I was thinking (hoping) it was a spark plug since they are the original ones, but when I swapped them, the misfire stayed in cylinder 4. I swapped coil packs, and again, no change.


I was thinking that swapping injectors would be the next logical thing to try, but this is not something I've done before in any car. I spent the better part of two hours looking for a good DIY or video, but couldn't find one. I found a general description of what to do, but it did not leave me brimming with confidence. So, a few questions:


1. Is it correct that swapping injectors would be the best next step?
2. Is anyone aware of a good DIY, preferably with pics or video?
3. Is it OK to drive the car in the meantime (gently and not too far), until the problem is solved?


Thanks!

 

What are the fault descriptions?
IF its a misfire I would do that. Are any of the plugs wet when you pull them back off? If thats not the case compression and leak down test time.

 

Sorry, P0304 is "cylinder 4 misfire detected" and P0300 is "random / multiple cylinder misfire detected". (I'm assuming it's just cylinder 4 with the problem, though, since no other cylinders are coding...)

I did not notice any plugs being wet, but I can check again and look for that specifically. What would it indicate if they were?

Assuming that they are, in fact, dry, is swapping the injectors the best next step? (I don't have a compression or leak down tester at the moment...)


Thanks.

 

In 6 years working MINI parts counter at busy dealership, never sold one injector due to issue / codes your MINI is having. In fact, I would say we sold about 1 injector in all that time for actual failure.

When you say in first post that your first step was to " swap " the plugs, what does that mean exactly ? Did you CHANGE the plugs or just move them around from one cylinder to another.

 

Interesting... So I guess fuel injector failure is unlikely...

By "swap", I meant moved them from one cylinder to another, to see if the error code followed...

 

I would not just focus on cylinder 4 due to this code....

 

Replace plugs first. Don't buy off eBay either. Seen a few engines end up with nice holes punched through pistons due to seller error stating correct plug for buyers MINI.

 

OK, I'll follow your advice and replace the plugs! (I'll just get OEM / no ebay!)

 

Seen crap load of "Denso" brands back out so yes stick with MINI brand, ( MINI sells at least three different brands of plugs depending on engine ) even if you end up not buying from dealer. Best guess, the Denso brand having multiple applications makes their crush rings from materials not to MINI specs, they don't crush at last 1/4 twist enabling their ability to blow out.....

 

This kind of stuff--which I would never know--is exactly why I hesitate to deviate from OEM plugs...

So I just ordered a set of the same plugs I'm replacing: Bero 12ZR-6SP2. Do you happen to know if they need to be gapped, or are they good to go out of the box?

 

If you bought exactly what was in the car from factory there is no need to regap the plugs.

The Coopers are notorious for destroying plugs in half of their rated lifespan, we are replacing plugs in 40k miles on Coopers vs the dealer recommended life of 100k, and at that point the gap has been blown out to over .055" (double the stock gap!)

 

Thanks for the info, Nick... Yes, bought the exact same ones: Beru 12ZR-6SP2. The plugs were looking pretty rough; I didn't think to measure the gap. I'll let you know how I make out!

 

We've seen them in excess of .060"!!

 

Holy cow 60 thousands of an inch !!! I have mine SET to almost .050 but I have a MSD coil pack to push the spark across.

When my MINI was stock the plugs came pre-gapped. BUT I would run a feeler gauge through each one to make them all the same. Typically one or two would be off a bit....

 

Hey guys,

Four fresh spark plugs, but no luck... Still running rough and throwing the same codes: P0304 ("cylinder 4 misfire detected") and P0300 ("random / multiple cylinder misfire detected").

I can confirm that while the old spark plugs were well-worn, none of them were wet or oily. As a reminder, I had tried swapping coil packs between cylinders 3 and 4, but the error code did not follow.

EDIT (ADDITIONAL INFO): Just for the hell of it, I tried moving all the coil packs around to see if there's any change in the codes, and while the misfire did not move from cylinder 4, I noticed a few new codes: C3064, C342D, and P0055 (HO2S heater resistance bank 1 sensor 3). After doing some searching on these, there was one guy with similar codes who had resolved the problem by cleaning the throttle body; there was another guy who had a burnt valve.

I suppose I can try cleaning the throttle body; any other insight or suggested next steps is welcome!

 

I would rent/borrow a compression gauge and do a compression check. if all compression numbers are good at this point, then I would consider swapping injectors, but like Raven said, they rarely fail on the non-turbo R56 cars, and are easy to replace.
let us know what the compression numbers are.

 

If not spark issue then could be issue in fuel dept but further upstream from injectors....HPFP ?. If this was an N14 Engine I would say maybe look at carbon buildup as the culprit but due to design changes with intake manifold ect we just don't see that with the N18.

 

Never herd of dirty TB causing issues in a MINI....and usually the inner walls of the TB are sometimes coated. Cant just use brake clean on it.

Those codes are for the most part unfamiliar to any MINI code chart I have...what are you using in the OBDII to read the fault codes ?

 

One thing possibly, any chance you have some bad fuel in the tank ?....Seen more than a handful of MINI's on a weekend rally where after stopping for fuel at a cheap mom and pop filling station, one or two in the group end up with engine issues very much like this. The remedy was a can of Seafoam in the fuel tank.

Maybe try pouring in a can of Seafoam....run it and see if it clears up.

 

Thanks BLoKe and rAvEn!

Yeah, I'm not gonna get my hopes up that it's the throttle body, but I'm happy to try anything that I can do myself, before taking it in to a shop! I'll also pick up a can of Seafoam and try that, too.

Will keep you all posted!

 

Update: Throttle body was not all that dirty... Some oil/dirt on the plate but it moved freely and smoothly. I picked up a can of Seafoam, but I want to wait until there's less gas in the tank so that it will be more concentrated... I'll also try to rent/borrow a compression tester. Probably won't be movement on this until next weekend, so please stay tuned!

 

arb63, I have the same model (2010 base model), but have about 130K on it. It started to have the similar symptom you have. But mine only happens after 20-30 min of driving. It starts shaking and eventually engine light comes up with P0304 code. I swapped the #4 coil with #3, but with the same P0304 code. I might try the sea form if that would help yours. Let me know how your troubleshooting goes.

TIA

jh

 

Hi JH,

Thanks, and yes, I'm going to try Seafoam... (I've been waiting for my wife to drive around a bit more so that there's less gas in the car, so the Seafoam will be more concentrated...) Did the Seafoam work for you?

 

arb63, not yet. I will pick one up today and try. Is your wife's running rough right after it starts or after driving awhile? As I mentioned earlier, mine does after 20-30 min. of driving..

jh

 

It runs rough right from the start, especially when idling and at low RPMS... It almost sounds/feels as if it's about to stall when idling, and it responds slowly when gas is applied... Good luck with the Seafoam; I'd be curious to know how you make out!