Hi all,

Have had my ‘18 Cooper S F56 for 6 years, 96,000-ish miles now, first brand new car I ever bought myself, and I’ve loved every second of it!

Currently, it is at the shop with a mystery CEL and throttle hesitation, which started after a couple of things.

1. I’ve had a K&N Typhoon intake system for the last 5 years. I know not everyone is a fan of these filters/systems, and I know it doesn’t do anything, but I enjoy the turbo noises and I’ve never had an issue with it. I discovered on cleaning the filter that some of the fiber on one side had worn away a small bit, so I ordered a new filter and installed it. Verified part # was correct, no issues there.

2. I replaced my gas cap, as the tether cord broke in half. Knowing I’m the type of dumb*** that will lose said cap, I got a new one and replaced it. Again, verified part #, purchased from FCP Euro but it is the correct OEM part for my model and year. I triple checked to ensure.

On the next drives after, my car starts to have a slight jerk or hesitation, which seems to indicate some kind of leak. CEL comes on a few drives later, reading a MAF fault (air mass too lean). Odd, I’ve cleaned and re-oiled my old filter before without issue. Nonetheless, as new K&N filters are pre-oiled, I clean the MAF but it’s not contaminated, nor that dirty, at least from what I could see. So, reinstalled it, clear codes, on my way. Hesitation comes back. CEL eventually comes back. Same fault codes. So, I get a new Bosch MAF sensor (same part # as the original), install it, and the code goes away on its own. Drives the same however, still hesitating. I finally give in, and take the vehicle to my local dealership, with which I have a good relationship as I previously worked there.

They do a smoke test and find a small leak near the oil filler cap gasket area. So, have that fixed and get the car back. On the second drive, the throttle hesitation returns on the highway. Ugh. At this point I think perhaps it’s all in my head. But, about a week later, the CEL comes back. This time, no MAF code, instead, it’s 118001, indicating a lean condition, along with 11CF30, indicating a mixture control fault.

So, I scheduled another visit. Interestingly, I got gas on the way, and on startup after filling up, the CEL goes away, and the car is driving like new. Then, on the highway, the CEL and hesitation return. So, having researched a bit, I see that the 118001 can occur with the common fuel tank vent valve issue. Which I’ve never had replaced before but have seen it quite a bit in client vehicles and online. They test it, and confirm it’s functioning very loudly but can’t confirm if it’s getting stuck closed or not. Nonetheless, I authorize the replacement.

The tech also noted I have a Dinan Elite, which technically could cause a lean condition. I realize mods are mods. However, I had it installed there (they are a Dinan dealer, or at least were) and it’s been on my car since 2019, and done 70,000 miles at this point, so I’m inclined to think that has nothing to do with it. But I’m not a technician so, could certainly be wrong. Dealer did check for leaks and confirmed gas cap was fine. So this could very well be just coincidental.

If you’ve made it this far, and bless you if you have LOL, my questions are:

1. Does this sound like a vent valve failure?

2. Would a new filter, of the same part # that’s been on the car for years at this point, cause an issue with a tuning box? I’d be very surprised if it could, but you all are the experts.

3. Anything else I should be considering? As I said, had a smoke test done and potential leaks checked and addressed

Thanks all in advance!

 

Out of curiosity, do you have a cat.less DP ?

 

Negative on the catless DP. I do have a catback Invidia exhaust.

 

Negative on the catless DP. I do have a catback Invidia exhaust.
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these cars are supposed to run a dry filter so maybe try replacing tne maf element and putting an alta filter or something else that fits in tne typhoon kit... tne maf is a perishable item too so it could have been already contaminated and with a freshly oiled filter been enough to ruin tne element..... it's worth replacing and there are some more accurate aftermarket elements from places like Delphi that will give you better a/f readings.
and for what it's worth ive used the typoon kit in several of my previous cars and when utilised properly tney do a lot more then make your engine sound better...ive built custom intakes on a lot of cars and when you let tne ecu adjust to new airflow and depending how nerfed tne manufacture has made tne car you can have so much torque that was being hindered thst you need better tread just to get traction out of corners or off tne line... tne mighty type R is a perfect example of a seriously nerfed engine....hope some of that helps..

 

I appreciate the reply, thank you!

So replacing the MAF was an early thought as well, and I did that. The code and stutter came back however, and upon a smoke test, found a small vacuum leak after the MAF near the oil filler area. Had that repaired, and the MAF code has not re-appeared. I should say, it still shows up on my Carly scan, but the last read mileage was while it was in for said repair, and I’d done 100+ miles on a few drives since, so I’m thinking it’s a history code as it no longer deletes out when I clear it.

I’m wondering if perhaps the small leak was maybe masking the true issue, which is possibly the aforementioned vent valve. Now that the old filter is gone and there is much better airflow, I’m speculating that perhaps it’s now come to light. I had been noticing a gradual drop in fuel economy over the last several months. It’s not a sharp drop, nor a major drop, but it is a drop nonetheless. I had attributed it to no longer having a highway commute every day, but perhaps it was part of this problem.

Supposed to get an update tomorrow, so will report back for future reference for anyone else who may come upon this.

 

If I strip out all the aftermarket stuff/etc., and reduce to gradual drop in fuel economy, and your suspicion about the tank vent valve, I come to...

...if you haven't replaced the tank vent valve, might replace the tank vent valve. See this post (if the link doesn't take you straight to post #11, just scroll to post #11) in a discussion about various B46/B48 hi-mileage "things."

Separately, I have a question for you for my own purposes. I would love to know more re this:

See this thread for why I'd like to know more. Feel free to post reply over there on that particular topic so we don't hijack your thread over here on your topic

 

I really appreciate the reply. That’s exactly my plan, having the vent valve replaced and hoping that is indeed the cure. I do feel like I smelled a bit of fuel vapor in the cockpit as well the night the lean code popped up, though I had read that as a symptom, so who knows if that was in my head hahaha.

I’m more in the camp at this point that the mods are a red herring (much like communism - obligatory “Clue” movie reference) and the valve is the culprit, either just coincidence that it cropped up when it did, or perhaps better airflow providing full song performance again compared to the dirty filter, which I suspect may have been slightly masking the issue. It’d be one thing if my modifications were new, but they all have 50,000+ miles on the car at this point. And it’s just the aforementioned intake, Dinan Elite, and Invidia catback exhaust, it’s stock otherwise.

As to your other question, will read through on that and see if I can provide an answer. I’m not the most mechanically savvy person, but I’ll give it a go nonetheless

Editing just to add: So in reading through the other thread, to answer your question, and going against the notes from my service tech, in my case, the oil filler cap itself seems to have been what had the issue, assuming its seal or gasket had failed and created a small leak. There wasn’t any documented oil leakage itself, so it appears that the issue was simply a bad cap, which was replaced.

 

Glad to help -- and appreciate your fast reply back. Re this:

Probably not in your head. 3 major things with this in mind.

1. Smelling fuel vapor in the cockpit is not always caused by this, but it is definitely an associated symptom at the level of "go check your fuel tank vent valve."

2. It doesn't take much to set this off -- apparently these valves are a little sensitive in this engine design. I read some time ago that topping off (meaning adding more gas after the pump auto-clicks off due to backpressure up the fuel filler neck) is a great way to mess up the fuel tank vent valve on a MINI. Well, I had a road trip through a state where you aren't allowed to pump your own gas. The attendant topped it off. I noticed fuel vapor smell in the cockpit and within about 2 weeks my fuel economy was going through the floor. I ultimately ended up making the post I referred you to. Since replacing the valve and resetting the associated adaptations, my fuel economy has largely re-normalized.

3. Back to these valves being a little sensitive, I hardly believe that that single fill up was root cause. I actually determined (don't remember whether I put this in the post) that the valve I replaced was years younger (2019) than the car (MY 2017, late 2016 manufacture). So in the course of what was then 111K miles on the car, including the replacement I did, that valve has required replacement twice. My guess is that repeated top-offs under the car's original owner were routine (pretty much everyone does it, unless you're like me and decided to stop for a specific reason).

I don't claim to understand the system design well, much less well enough to know why topping off the gas can lead to this. But it's definitely a point of discussion out there. And BTW, even though mine sprung an actual leak that I was able to identify, most discussions don't include that (guessing in no small part because the fluids I noted were unknown to me until I realized my hand was wet from physical contact with the valve -- the fluids would normally evaporate away rather than drip).

FWIW that part is so easy to replace you could get your own cheap online and DIY it. I did mine for about $35.

 

Likewise for you, thanks very much for your help as well, and for getting back so quickly!

Looking back, while I usually try to avoid topping off as I’ve read this can cause that issue, I know I’ve had to a couple of times over the life of the car at least, where it stops short of filling the tank and I have had to resume it. Probably less than 10 times in 6 years of ownership, but as you said, it’s a sensitive part, so it is very possible it built up over time.

I also do remember recently where I had some kind of issue actually getting fuel to pump in. I attributed it to a bad fuel nozzle at the gas station itself, so I went to another pump and it worked. But I wonder if inserting and removing a couple of times did some damage as it wasn’t too long ago. Definitely something I’ll be MUCH more mindful of. I love my car and as I approach 100k, I’m hoping to get another 50-60k out of it over the next couple of years. My goal is to maybe then trade in for the new ICE Hardtop, I like the more minimalist design vs. the current LCI2 with the goatee. So, long-winded point being, I want to be the best owner I can be and treat my MINI well so it keeps going. It’s been a very reliable car overall.

A couple little things like this, and the engine mounts, but it’s always been dependable.

Sorry if I wasn’t a ton of help in regards to your question, it’s a bit over my head knowledge-wise so didn’t want to BS you🙂

 

No worries re my other Q - your feedback was actually helpful. I had replaced my oil filler cap already so been there done that and my off-thread issue must be something else.

Again glad to assist. Re having trouble getting fuel in -- that is also an associated symptom, as wacky as it sounds. Bottom line as you are pumping gas into the tank, you are pumping air out of the tank. Anything that restricts that exit of air will result in backpressure to the nozzle, which will in turn cause the nozzle to shut off. Smart design. But if you get some wackiness where you have backpressure that has nothing to do with whether you have filled up the tank, that's where it can get weird.

Most of the discussions about the fuel tank vent valve that helped me were in BMW forums, and the most helpful were discussing the same engine that is in the F-series MINI lineup. The most common symptoms were low/dropping fuel economy, gas smell in the cockpit, and trouble putting in gas at the pump. Trouble putting gas in at the pump usually showed up before fuel economy issues were noted. Whether there was gas smell in the cockpit seemed to be a little hit and miss. So basically, you've got all the textbook stuff going on. I wish again that I understood it from a design standpoint -- but the upshot is you're not alone!

My F56 S just rolled 118K and while I have to say I regard it as "an engineer's car" based on my experiences, if I weren't hands-on I would probably be driving it around just like everyone else not knowing anything was "up" and getting the occasional surprise -- just like with any car. And I have put far more miles on it, far more quickly, than originally planned (road trips). Minus one or two particular issues, it has held up pretty well in that context.

 

I'm glad I could at least provide a little assistance then!

This honestly is making me more and more confident that the vent valve is indeed the culprit here, just based on the symptoms and this conversation. Which is oddly relieving, as I'd much rather it be a mechanical part that failed vs. some kind of gremlin that is hard to chase down. The fact that issues with filling up are a symptom is somewhat tell-tale, as that happened shortly before I started having issues. It legit must be coincidental with the timing of the filter change and whatnot I suppose. Especially as I've had leaks and whatnot thoroughly checked at this point otherwise.

I've learned quite a lot reading this forum, so thank you for being so helpful. I will report back to confirm the issue once I get it resolved, supposed to hear back tomorrow.

Glad to hear too that yours has been solid. I definitely am a brand loyal buyer for life, I've had 3 MINI's now and it's the only car for me. But, I definitely want to get some further use out of this one. A) It fits my needs and I enjoy it. B) Interest rates are stupid LOL.

 

I had two (possibly three) of these -- IIRC, after the attendant top-up but before I noticed my fuel economy was getting weird. It wasn't consistent, but they were clustered together and freaked me out, because the behavior was new and I had picked up that it could indicate trouble -- I think that is part of what set me off to deep forum reading in the first place.

 

Interesting, that does seem pretty definitive then. Yeah, I bet I’ve actually had this issue for awhile and it just hadn’t shown its full hand yet. Excited to get better fuel economy then, hopefully :D

 

I arrived at the conclusion that topping off gas tank is BAD ! I will from here on out quit fueling @ the first click of the pump handle.

 

Quick update today:

So, new vent valve indeed solved the lean code, at least so far. Had it sent on a 60 mile drive today and it didn’t return. BUT, the airflow/air mass too low fault did.

So, going down the list of things it could potentially be, especially as it’s already been smoke tested and had MAF replaced, I dropped my Dinan bypass off to see if disabling the Elite drops the code. If the Dinan is the culprit, I’m likely going to just keep it off. I’m assuming I can still keep the CAI and catback on however, shouldn’t be an issue I wouldn’t think? Dinan was the last thing installed of the 3, and the other two were fine before.

Nonetheless, will update as I know more, kinda hoping it is the Dinan at this point and I can just remove that and be on my way.

 

Update/Resolution:

So, had a couple of things done.

1. Fuel tank vent valve was replaced. However, Air Mass fault kept returning and technicians tested everything else they could and didn’t find anything wrong. So, I took my bypass out for the Dinan Elite. They plugged that in, light/fault went away and never came back.

So,

2. Had Dinan Elite removed completely, and got the car back today. Am happy to report that it is seemingly driving like new again finally. No noticeable hesitations whatsoever.

At this point, I’m thinking one of two things, and my advisor agreed. Either the new filter somehow freaked the Dinan out, or the module itself failed and just happened to be around the same time. I’m almost wondering if it actually had failed awhile ago, as driving my car, it didn’t feel any slower than before. So am wondering if perhaps the Dinan failed some time ago, and it just came to light when it had better airflow and it had to adjust.

A buddy of mine is the service manager there now, and he said they’ve been seeing issues with the Elites more recently, even years later, so starting to think that was indeed it. I’m just happy to have my car back, it’s been missed.

 

Welp, back to the drawing board.

Further update, today was a somewhat chilly morning, I started the car up to go to work. Idles perfectly fine and is driving perfectly fine. Then, going around a curve, I feel what seemed like a very faint stumble, followed by the dreaded CEL.

So, I pull codes again, and lo and behold, good old “Air Mass Too Low” is back once again! Yay!

At this point, I’m suspecting the K&N replacement filter is the culprit here. Considering I was having no issues before installing it, and have been having intermittent issues since. Mind you, this conical filter is the same part # as the one I’ve had on the car for some time now, with no issues.

But, after checking, cleaning, and replacing the MAF, replacing the fuel tank vent valve, and removing the Dinan Elite, plus the timeframe being lined up, I have no idea what else it could be at this point. I’m getting no misfiring codes, so I’m not suspecting injectors, nor any other engine-related or fuel mixture faults, nor is the car stalling or driving particularly poorly.

Will update once I know more! I sadly lost my factory airbox in a house flood last year, but I’m looking into grabbing one online and reverting the air system back to stock to see if it resolves the fault.

 

Odd. I'm out of ideas myself, though with all the aftermarket stuff involved I don't have a personal reference point.

Did find a BMW forum thread based on a Google search for "air mass too low" that ended up with the owner finding one of the CCV hoses attached to the charge air pipe was not attached -- big leak between the MAF and the turbo, basically.

Link: https://f30.bimmerpost.com/forums/sh....php?t=2022923

Engine under discussion in that thread is a B58, sister to the B3x and B4x engines in the F series MINIs.

 

Appreciate that thread! That was definitely a thought as well. I did check post-MAF and couldn’t see anything loose, disconnected, or broken, but that doesn’t mean there isn’t something up. I’ll definitely see if I can find anything.

 

Hi everyone!

Just wanted to update this thread and provide a resolution. After all of the above, turned out my car just really did not like the replacement K&N filter. Tested with having the stock air box put back on, and it’s run completely fine ever since! It’s actually kind of a blessing in disguise as reverting to stock has helped my fuel economy immensely.