So I have a new issue just popped up this week, car is stumbling pretty bad during mid to high acceleration. Sounds and feels like what happens when you abruptly lift while accelerating, which I think is due to the bypass valve opening and dropping boost.

I think its getting worse I was trying to pass a car earlier in 4th gear going from 45 – 60mph. everything was going well nnnaaaaahhhhHHHHHH then na na na na na nahhhhhhhh and I let out(<<<<<lol pretty accurate noise description in my mini.
happens in any gear and allmost any rpm, just depends on how much throttle i give it. no codes no lights, idles and runs fine other wise.
Any thoughts

 

Clutch slipping? Just a guess , as mine was going out it would do a similar thing upon hard acceleration.

 

Check your plugs.. I had that and one was done... Simple fix.

 

 

check intercooler boots also, make sure they are snug and secure and in good shape, Mini will do all kinds of weird crap when they are leaking.

 

that sounds more like slipping.. might be your clutch? do the RPMs go up faster than the speed? shake the car at all?


my bad plug was more of a misfire.. the would go burr burr burr burr.. this sounds different.

 

newish alta boots, 2 day old tensioner, no rpm jumps, cluch was replaced probably 15-20k miles ago

 

i fell like the BPV is fluttering or something. going to swap out my demon coil with the old stock one after work and see if it helps

 

got worse and threw a code last night p0302 which is #2 missfire.

now it sounds just like in the video but machine gun fast.

I'll just tell people i got a 2 step that kicks on while crusing, till i figure it out.

i also bought a scanguage 2 from auto zone. same price as any place online

swapped out the coil, did not make a difference

 

I'm having the exact same thing going on (P0302). Replaced BPV with detroit tuned, gates racing belt, plugs, profile gasket, crank pulley with alta 0%, went through intake and resecured all clamps with new ones, checked intercooler boots.

I am thinking either one or both of the Map sensors, or the dreaded bad valve(s). Had the head off to take a look at the valves, and nothing seemed broke/burnt, but that doesnt mean a seal isn't seated right.

good luck to you, let me know if you beat me to the punch fixing yours and how you reached your solution, as I promise to do the same.

 

solution ¿?

 

Unfortunately due to the holidays mine is on the back burner to work on. Its not a daily driver, so I am fortunate to be able to wait. I can say that the car is fine right when you crank it up. You can drive it like you stole it while its warming up, but somewhere between halfway warmed up and normal operating temp it starts to do the sputtering thing if you 'get on it' so to speak. If you drive it normally (economical shifts/rpms), it will drive fine...all day like that as far as you want to go, however, if you need to hit the gas for anything you'd better be ready to let off as soon as it starts to sputter or you'll trip the SES light and go into limp mode.

I've done it enough now to where if it happens, i just shut the car off while i am moving, then restart it either by key or by gear to get it out of limp mode. The light has to be reset by a scan gauge, which i keep in the car. No other codes are being thrown, just P0302 misfire cyl #2.

I do want to change the fuel filter, map sensors, and manually clean the injectors. I don't really see how this could be valve related since the car runs fine at times and then doesn't at other times. I've been told, although i am not certain whether its true or not with these cars, that if you have a bad valve the symptom is there whether the car is cold or warm. It really does seem like an air fuel thing, whether the cylinder is actually being starved for fuel, or the car is just getting a bad reading/measurement of air flow, which is tripping it up. Its a very odd symptom, and from the months of research i have done, finding several people who've had this same problem, I cannot say with certainty what the exact fix is since there are SO MANY things that can duplicate this symptom.

This car has really proved that i am no master mechanic, but instead at the mercy of learning through trial and error. If anyone wants to shed light on this topic (our situation) i will be all ears.

Till then, happy new year, cheers.

 

Updates ?

 

As I stated in another recent thread, I feel that I may have remedied my stumbling with new plugs. I did also remove and reinstall the IC boots and noticed small cracks in the rubber but don't think they are bad enough to cause problems (yet)

 

I found one of my plugs backed out about half way. Tightened her back down and was good to go

 

did you ever fix your issue? i'm having the same exact problem.
I've replaced:
Plugs, wires, coilpack, fuel filter, both O2 sensors, DT BPV
I'm out of ideas....

 

You're getting P0302 as well? After changing the plugs and everything is it still misfiring on cylinder 2?

 

The car drives and accelerates fine as long as i gradually push the accelerator, however if i give it any more then say 1/3 throttle or more it behaves exactly how his did in the video.
When the problem first started I had the P0302 and the code for an O2 sensor. I replaced the plugs, wires. Didn't help. Then Replaced the coilpack, didn't help. It didn't throw any codes unless i jump on the accelerator.
I replaced the first O2 sensor, same problems, so I replaced both even tho it didn't throw a code for the 2nd one.
After that didn't help is when i replaced the fuel filter. Last night i replaced the BPV with a Detroit Tuned one. Soon as i jumped on it it threw the P0302.
I'm really out of ideas at this point.

edit: It doesn't throw any codes unless i let it stumble for a while, if it starts to stumble i let off the accelerator and try my best to gradually get it to accelerate. codes it throws are P0300, P0302, once it threw P0304.

 

Does the car hesitate to start at all? Have you checked your fuel injector? P0302 can be possibly a faulty injector. Some info HERE. If that isn't your cause then you may want to do a compression/leak down test.

 

Have you done a compression test yet? Injectors aren't a very common failure point on these cars.

I would be interested to see your compression numbers before you dive into removing injectors.

 

no hesitation on startup. Have not checked fuel injector. I'll look into that and do a compression test. Thanks for your help !

 

ok, compression test
Dry
1 = 160
2 = 162
3 = 160
4 = 162

I think those #'s are pretty good, at least consistent. not sure what the OEM spec is supposed to be. Didn't think it was necessary to do a wet test.

 

next i will be taking the fuel injectors off and test them. any idea what the resistance should be? also what voltage do they use?

 

You're welcome. Bentley Manual states compression range of 9-13.5 bar (131-196 psi) and a maximum difference between cylinders at .5 bar (7 psi). You look to be good and there isn't one cylinder far below the others.

You can swap the injectors and see if the misfire changes to a different cylinder to test. Some good info here on removing them if needed.

 

well, after cleaning out the injectors and the vacuum line to the regulator it's running much better, not perfect but much better. I'm thinking I might need to replace the FPR. what do you think ?