Hey guys. I have an 04 MCS R53 and recently during driving I have been feeling this random lag in the cars acceleration. During normal driving, lets say I stop putting throttle for about 10 seconds and the car is just rolling down the street, after those 10 seconds I give sudden gas and as it accelerates it basically lags. I am trying to think of another word that may help me explain the issue better but lag is the best I can think of. It isn't an issue with the coils with a delayed response, no its not that. It's basically like a half second of the car just stopping it's acceleration and than accelerates right away. I am thinking it has something to do with the fuel system like something is dirty and it clogs up after I suddenly put a lot gas, Or its the start of a problem that will become increasingly big.
Let me know Thanks!

 

Any codes?

trims?

does it yo-yo?

 

I recently had a check engine light and it was an evap leak near the gas cap so I was thinking it was the leak that was causing the lag but i recently got it fixed and there is no check engine light and still theres a lag. And what do you mean my trims? The trim of the car? If thats what you mean its the S. I have the supercharger and also what do you mean by yo-yo?

 

My guess, since I don’t have an R53, is something the bypass valve system. When you are just cruising down the road, the valve is open to bypass the supercharger. Then, when you go to accelerate, the bypass valve should close to so the supercharger can pressurize the intake. Sounds like the bypass valve isn’t closing as fast as it should, and you’re getting a lag in boost.

 

Had the same problem on my R53 and discovered it was the DSC causing the lag. Turn yours off and see if that solves your issue.

 

What is DSC? What does it stand for and how do I turn it off?

 

There should be a toggle switch below the radio that is labeled DSC (dynamic stability control). When you hit the toggle switch an illuminated logo pops up on the instrument panel that looks like a triangle inside a circle. When lit it means your DSC is off. You will need to turn it off each time you start the car.

 

I have ASC not DSC but it displays the same picture of the triangle. Is that the one your talking about?

 

Yes, turn it off and see if that solves your lag issue. Again, don't forget that it's on automatically and that you'll need to turn it off every time you start the car.

 

Okay, I'm about to go home in a couple minutes and drive it. I'll let you know what happens.

 

fuel trims. You’ll need a obd code reader…

yo-yo, power on, off, on, off…that can be the bypass valve going out

 

I do not have "yo-yo". Rarely do I get a random drop in rpm during idle but it like drops about 200 rpms thats it which I think its just a result of the car heating up so it lowers the rpm to not overheat. I forgot the code I got for the evap leak and I tried finding it and I can't find it.

 

I drove it the other day and I turned off the DSC or ASC and the lag was only lessened. I used to feel it at a greater level with the DSC or ASC on but with it off I still feel the lag but its just less intensified. What do you think this means? Could this mean I need to replace my bypass valve?

 

You can check the tension on the BPV spring by simply reaching down and opening/closing it by hand -- should be difficult to move. Even though you say you're not throwing a code I would be more suspicious of a vacuum leak causing your lag issue. I would perform an inexpensive smoke test (to ID a leak) to eliminate that possibility before spending money on a new BPV.

 

Belt and tensioner ok?

 

I see, I will check that next morning and let you know. I also want to just say that if the ASC or DSC had a slight affect on the lag (what I mean is that it slightly helped reduce the lag), at that point shouldn't it only have to do with the ASC or DSC?

 

Haven't checked that either will check tomorrow morning!

 

My MC40 was experiencing a SERIOUS lag when I first bought it. I researched everything, including everyone on this site, and could never find a reason for it to happen. I happened to run across a single, old post about turning off the DSC. I tried it and the problem immediately disappeared which is the reason I run with it off at all times. No one has ever been able to explain to me why that works and I can't figure it out myself. I just know it worked. However, the lag problem completely disappeared on mine - did not hang around for a bit which it sounds like your's is doing. I'm still leaning toward a vacuum leak as being your issue if you've checked everything else like, plugs, plug wires, injectors, coil, etc. Another path may be to contact adriancl on this forum (who tunes many of our cars) and have him read your MINI in real time to see if he can unveil the problem.

 

Sorry for responding so late I did not get notified of your reply. My uncle who gave me this car told me when he did the 17% alta sc pulley he did the belt tensioner with it so it is relatively new. I do not know about the belt. Are you saying that there could be some slippage with the belt when I accelerate suddenly? Because I also have a weird burning smell anything above 3,000rpm. I read somewhere here that it was possible that if my pulleys and belt are of old age it is possible they slip to which I get a burning smell and there is a lag in my acceleration? Could that be it?

 

Again sorry for the late response I did not get notified of your reply for some reason. I remember reading your other posts about DSC and I tried it out and it does not work. I ripped it down one street and it still lagged the exact same. I'm looking at bypass valves to purchase. I heard that the detroit tuned bypass is tuned for this exact problem. But it is really expensive for me so I was wondering can I just purchase a replacement oem bypass valve for it and it will resolve the problem?
I am also talking to adriancl about a tune for mine. I will ask him about it.

 

If you're going to check the belt for age/slippage you may also want to look at your crank pulley to see if the rubber center is starting to separate from the outer metal casing. That could make a burning smell and lead to a pretty serious failure.

 

I have the alta 2% enlargement pulley installed. Or are you talking about the seal behind the pulley?

 

He's talking about the stock crank pulley, which is also a harmonic damper. It has a rubber toroid connecting the inner and outer portions of the pulley that can fail. It shouldn't be an issue if you have a solid pulley, though quite a few people claim those lightweight pulleys are no bueno because of the increased harmonics.

 

I recently went to auto zone and I asked them to run the computer through the mini and the harmonic balancer came up as the most likely solution yet but the guy at auto zone said that it is most likely NOT the harmonic balancer. That is just what your issue falls under like category-wise which I did not really understand. It also did not make sense to me because they are talking about the stock crank pulley while I do not have the stock crank pulley.

I got three codes;
P1688: Monitoring Mass Airflow
P0507: Idle Air Control System RPM Higher Than Expected
P1477: Leakage Diagnostic Pump Reed Switch Did Not Open

Could P1477 be my bypass valve not functioning corrrectly?

 

The lag and the burning smell are classic crank pulley core separation symptoms. What crank pulley do you have installed?