Hi all,

Been having a really annoying issue with my 04 MCS for the past month and I can't figure out what it is.

It all started like this: some nights when I left for work (at around 11pm - 50 degrees F) my car would start up fine. But. When I would accelerate (this is a manual by the way) somewhere around 2700 rpms it felt like I would lose power, or possibly misfire. No worries. After maybe a minute or two the problem would disappear.

Well now, when I leave work at the same time, the car starts up and immediately misfires - CEL comes on which points to misfire on cylinder 1. After maybe 10 minutes of driving on the freeway at 60mph and the problem eventually goes away. Although the car audibly misfires when I decelerate in gear.
Spark plug wires are new, I had a mechanic take the valve cover off and inspect the inside (I had him replace the valve cover gasket for me). Everything looks fine and spark plugs are good (ngk, maybe 3 years old). One thing to to note - the coil pack is also about 3 years old but I don't think it's OEM. Which has me thinking that might be the issue. There's some corrosion on post 3 but I don't think that's the issue

I think it's electrical. Maybe a bad ground? Again it ONLY happens when I leave work at night. Could be that darned coil pack. maybe some condensation? Im at my wit's end here. Any help or guidance would be appreciated!

 

First thing I'd do is replace that coil pack, if you don't have the OEM, get one, many aftermarket coils have been known to have issues.
if you have to wait to order one, something you can do right away is either get new set of plugs, (no matter how old the ones you're using are) or at the very least pull #1 and # 4, swap them, you see if the misfire changes position.

 

misfire could be all sorts of stuff... rent a tool from autozone and do a compression test of the cylinder...

 

Hi all,

Quick update. I ran through a full tank with techron. I'm also getting a misfire with low fuel pressure code. The plan is to replace the fuel filter, and see how that works. If that doesn't work, next step is to remove the fuel injector and soak it in seafoam to see if I can clean it up. I'll keep an eye on the codes after that happens and keep everyone updated

 

Another update:

Had the car sit overnight (it was raining like hell - cold as hell)

Started her up this morning and she turned over no problems. Revved the engine and no misfires. The techron helped. The fuel filter comes in tomorrow morning.

Fingers crossed that everything turns out ok

 

Regardless of whether or not the new fuel filter helps, I would replace the coil pack for a genuine MINI one any way. Are the plug wires genuine MINI? If not, probably replace them also. These cars don't need "fancy" coils or wires over the original ones.

 

Alright another update:

So I drove the car another 200ish miles back home with the fuel system cleaner and new fuel filter. She drove more or less like a champ. No issues whatsoever... until..

We got back home, tank was empty so I filled her up again (chevron, super). Within a night or two, after leaving work, same as last time: Misfire. I was livid. The problem persisted pretty much every night, and sometimes in the morning too (although not as badly). I replaced the coil pack to a genuine part, as @CRC suggested (albeit not a suggestion to fixing my problem but hey, let's give it a shot). Still nothing, Great. As I neared then end the next tank of gas, I figured i'd add another bottle of techron when I fill It up. Here's where things get weird - the problem completely goes away. Like completely. The car turns over no problem. WTF?

I'm nearing the end of that that tank of gas and the misfire is slowly returning. So my question is WHY is techron making my issue go away, ONLY when techron is in the tank?

Help!

 

Borrow a coil pack from someone ?......and then see what happens.
My money is on that being the issue.

 

Not likely. The coil pack I initially had (the non OEM one) was only 2 years old and as I said earlier, the problem only occurs when my car sits for more than 7ish hours in and cold starts.

​​​​problem still occurs exactly like it did initially with the new OEM pack I bought last week

 

Do-the-cheap-stuff-first!
Change the plugs - $10.
Keep the old plugs in order & check their color.
Use the best fuel you can find.
How long is your commute? It sounds to me like the car needs some exercise.