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Hesitation/Stutter on over-boost/full acceleration

125K views 39 replies 28 participants last post by  baines.j2 
#1 ·
Hi all,

I hope you can help me, my car has had this problem for some time. I took it to Mini Nottingham (Sytner's) and they, ahem, 'diagnosed' deteriorating spark plugs which they duly replaced under warranty. Needless to say it didn't fix the problem. The car drove a bit better but the problem came back.

Symptoms:

Under full acceleration and at highish revs the engine stutters badly causing a dramatic loss of power, this is accompanied with loud metallic pinging noises for the duration of the stutter (detonation?) and smoke from the rear. I have not determined what colour as yet because it's more noticeable it the dark when illuminated by others' lights and of course all smoke looks similar in the sodium/halogen glare!

If you back off the revs it's fine and probably won't do it again until the next day, for example. It seems to happen just once a day and the first time I boot it; usually when in second or third gear. It won't happen if I am tootling along in fourth or fifth - it's almost as if I need to take it by surprise with a sudden & quick increase in revs.

In addition to this the car and probably unrelated as this is more recent, the car's coolant has turned a murky grey/black colour - no smell of fuel or combustion gases though.

Any ideas?

Hope someone can help!!

Paul
 
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#2 ·
Hi Paul

I'm not going to be very helpful here other than to say I have a very similar sounding problem.

I get the 'metallic' sounding noises, when the rev's pick up quickly, every few days once during a trip and then it goes. I haven't noticed any smoke though. Mine doesn't sound quite as bad as yours though, it just holds off accelerating with a slight stutter and noise very briefly. Window down the noise is quite evident.

Its a bit of a pain that its so intermittent, it never does it when anyone else is in the car.

If you find anything out please let me know

Cheers

Matt
 
#3 ·
Hi Paul,

I had what sounds like the same problem since december up until a few weeks back. As you describe, pottering around you wouldn't know anything was wrong, it's only when you push it. I experienced the same with it only really happening once a day too.

The garage changed the spark plugs & oil thinking this would solve the problem. As with yourself, it didn't. After further diagnostics it appeared the pressure was low in one of the cylinders. The garage dismantled the engine expecting to find a burnt exhaust valve. This wasn't the problem, it turned out to be a damaged piston head (a big chunk was missing). I have just got the car back and having to ease the engine in again after having all 4 heads and rings replaced. 5 months out of warranty, not happy!
 
#6 ·
Sorry guy I have been away for a few days it sound the turbo is stalling and surging could be the air bypass valve wil have a look at my mate r56 JCW over the weekend and have a think but for a quick check I would deffenatly get the cylinders checked like clubbie says find someone with am enderscope pop out the plugs and have a quick look at the piston crowns rule it out it's easy to do will get back to you

Mark
 
#8 ·
i could not have expleained it better, my 57 plates does the same,( not sure about the smoke tho) brought it in to mini while under warranty....yes u guessed it! nothing found...but it's just out of warranty now a few months...im not too good with engines, and dont trust mini at all! had mini's for 10 years now..for the love of the car..not the service.
i really hope you get it sorted..
andy

if anyone knows of a good mini garage in or near merseyside please let me know
happy motoring
 
#9 ·
Hey there guys,
had exactly the same problem as mentioned in the above, apart from mine was through out the rev range, and was producing black smoke from the exhaust when this occurred. This would possibly only happen once or twice weekly, then went to daily.
After having my local dealer look at it (whilst i was there observing), it came up with a fault called "Super knocking".
This has something to do with the engines timing, so they replaced the knock sensor and reset all the faults.

Touch wood, been a dream ever since, and maybe its just me, but even feels quicker. Now wondering if the timing had been variating for a while.

Hope this helps. Happy motoring

'09 Cooper S
 
#10 ·
I have the exact same problem on my r56, 2007 Mini Cooper S. The car has been returned to Douglas Park - Glasgow almost 4 times, and no faults have been found.

The car has only made this noice - metallic pinging - maybe twice or three times, and it is accompanied with the smoke. However I have also noticed a hestitation/stutter under accelaration and a degree of white smoke from the exhust at start up.

The hesitation is most notable on start up and it is quite worrying, especially under mild to heavy accelaration in third gear.

Hope to get to the bottom of this in the near future.

Many Thanks

David
 
#11 ·
I have the same problem, I actually printed off some of this thread and left it with the dealer. They said the sensor needed replacing, has to be ordered from Germany apparantly.

Will be fixed under warranty (new engine needed due to death rattle, only silver lining is the warranty).

I love the car, but having owned performance honda's in the past, I really do miss not having to worry about the reliability of the engine.
 
#13 ·
im having the same issue.. when i WOT with gear 2 and 3, around 3000rpm, the stutter is so bad, its like im riding a horse! but if i were to do a gentle gradual hard acceleration, the rpm will climb smoothly.

had my mech checked the spark plugs and they r fine. but the ignition coil packs are kinda rusty and corroded.

tomorrow im bringing down to MINI for their mech to test drive..

btw its a 08 R56 S with 71000km.. and yes.. outta warranty.. :angry:
 
#16 ·
The problem is the PCV rear pipe

Hi, I have a PSA THP150 in a Citroën DS3. And I hear the most knowledgable guy on THP's in the world hangs out here? :)

Engine(s) is totally standard, no modifications.

From about 1000 miles from new, the engine would occasionally detonate under partial to full load, in gears 3,4,5,6.

The Citroën dealer said that they could find nothing wrong, and there were no fault codes.

From about 5000 miles occasionally, it would detonate and give an engine faulty - repair needed warning. Citroën once again said this is normal!!!!!!!

The car got to 9500 miles, and whilst driving at 60mph started detonating again under partial throttle. When stopping and investigating, the engine was now misfiring. Turning the engine on and off, and disconnecting the battery for a while did not cure the misfire. When I finally got home, I checked the plugs and found no1 cylinder spark plug was oily. The others were normal. Also, around the top engine cover breather pipe there was oil haze as if oil had sprayed out momentarily.

I decided to do a compression test, and on no1 cylinder, this was down at 30psi, which is seriously wrong.

The car was taken to the dealer, who investigated and said the engine needed replacing, and they decided to fit a brand new engine. This took 2 weeks for them to order and fit. The new engine was complete with new turbo and new ancilliaries (alternator, AC compressor etc)

When I collected the car, for 1 day it was fine, but on day 2 (after 50 miles on the new engine) it started detonating under partial load again in exactly the same way before the last engine was destroyed.
The fix

Hi everyone

Due to the THP engine being direct injection, i.e direct into the cylinder, and the way the PCV (positive crankcase ventilation) is laid out, a lot of oil haze gets sucked into the combustion chamber, past the valves and is burnt.

Well, that's how it's supposed to work!

In reality, this oil haze can cause numerous faults to standard engines, and any remapping or free flowing air filter arrangements can magnify the problems.

The 2 main problems are:-

1. Oil carbonising around the intake valve, which causes very rough running which then requires the dealer to spray a special solution to dissolve this carbonisation (like Seafoam)

2. When shutting down, because of vaccums within the engine and the layout of the rear PCV pipe, oil is left to collect in it, and when starting, assuming you drive easily until warm, is still sitting in the pipe because of the Valvetronic valve system on the THP engines, which under light load only partially opens the valves. Then, under harder acceleration, this oil in the pipe is sucked into the combustion chamber which has the effect of reducing the octane rating of the fuel (think putting diesel in a petrol car) and can cause detonation, which sounds like a tinkling or loud clicking sound (the knock sensor is frantically trying to compensate by adjusting the timing)

The cure?

Well, PSA are fully aware of the problem, and on the latest THP200 that is fitted to the DS4 DSport and Peugeot RCZ THP200 the rear PCV system has been deleted, and the reason for it being kept hush, is because it's not "eco" friendly. But hey, neither is requiring a new engine every 4 months

Google THP PCV delete for the fix as I can't post links as I have less than 15 posts
 
#17 ·
The problem is the PCV rear pipe



The fix

Hi everyone

Due to the THP engine being direct injection, i.e direct into the cylinder, and the way the PCV (positive crankcase ventilation) is laid out, a lot of oil haze gets sucked into the combustion chamber, past the valves and is burnt.

Well, that's how it's supposed to work!

In reality, this oil haze can cause numerous faults to standard engines, and any remapping or free flowing air filter arrangements can magnify the problems.

The 2 main problems are:-

1. Oil carbonising around the intake valve, which causes very rough running which then requires the dealer to spray a special solution to dissolve this carbonisation (like Seafoam)

2. When shutting down, because of vaccums within the engine and the layout of the rear PCV pipe, oil is left to collect in it, and when starting, assuming you drive easily until warm, is still sitting in the pipe because of the Valvetronic valve system on the THP engines, which under light load only partially opens the valves. Then, under harder acceleration, this oil in the pipe is sucked into the combustion chamber which has the effect of reducing the octane rating of the fuel (think putting diesel in a petrol car) and can cause detonation, which sounds like a tinkling or loud clicking sound (the knock sensor is frantically trying to compensate by adjusting the timing)

The cure?

Well, PSA are fully aware of the problem, and on the latest THP200 that is fitted to the DS4 DSport and Peugeot RCZ THP200 the rear PCV system has been deleted, and the reason for it being kept hush, is because it's not "eco" friendly. But hey, neither is requiring a new engine every 4 months

Google THP PCV delete for the fix as I can't post links as I have less than 15 posts
Wow thanks, my car is going into Mini on Monday for a service and I've cited a few warranty items that need investigation, this being one of them. Today I ran the car out and couldn't repro the problem with an ELM327 and laptop connected to the car. so I let the car sit a while whilst I had lunch, etc. Then the next time I took the car out I was able to repro it. I can't see much wrong with the data if I'm honest, but then I'm not an expert. I came on here to see if I could get help analysing it and read the above! Somehow my subscription to my own post had been removed!

So if I am reading this right; in essence there's nothing Mini can do to fix this problem so we are stuck with it.

This goes a long way to explain the intermittent lumpy idle my car suffers from too.

Anyway, looking at the data available to the program I am using on the car (PCMScan) the knock sensor if not a valid PID, does anyone know how I can get this logged to file so I can hit Mini with it on Monday?

What are other people doing about this problem and have BMW admitted the issue to anyone?

If there's never going to be a fix for this they'll be getting my car handed back to them when it's out of warranty!
 
#18 ·
Ok, just read the 'fix' for this here:
h t t p : / / w w w . e t u n e r s . g r / e n / i n d e x . p h p ? s = 1 2 & t = 2 9 9
I'm going to print this and take it with me on Monday! I'm also going to ask them what they propose to do regarding cleaning my intake manifold and carbon build up in my engine!
 
#19 ·
I've just pulled the PCV hose off the inlet manifold and it's dripping with oil, it is also showing signs of venting oil haze onto the top of the engine, grrr. If this is removed and the fix above applied - what happens to the blowby gases from the crankcase, they'll have nowhere to go. I presume this will lower blowby because of the increased crankcase pressure, but I presume this increase in pressure could cause a future seal failure - or is there another venting mechanism on this engine?

I remember Porsche suffered from a similar problem on the 924 turbo - crank pressure switching from negative to positive (or the other way around) caused oil to rush into the inlet manifold unexpectedly, they fitted a canister (about the size of an oil filter) to the crank case pipe and that allowed the oil to be collected instead. Crank gases were piped into the top of the canister and any oil would condenses/collect on a gauze inside the canister then drop to the bottom before the gas was passed on.

Simply removing the gas recycling can't be a permanent fix can it?
 
#21 ·
No fix I'm afraid. MINI agreed to investigate and had the car in for two days. They couldn't replicate the problem so they asked me in to help. I drove the car and couldn't replicate the issue either. They'd serviced the car though and this usually makes the problem disappear! Presumably because the new oil doesn't atomise as readily.

They conceded that the car had logged super knock errors on the diagnostic computer so they know there's a problem but their hands are tied to the diagnostic machine's recommendation of replacement plugs unless they can experience the issue first hand. They also advised I use super unleaded fuel in case the fault was caused by poor quality juice, however, in my experience this makes no difference.

I spoke to a technician for a while and took a look at the latest Mini Cooper S engine - which has a different head design - and I couldn't see any breather pipes connected to it... hmmm.

They did give me an open door invitation to take the car back the moment it starts misbehaving again. It has started doing it again but I can't reproduce it on demand. I think the oil needs to get a bit older first.

I just want MINI to admit there's an issue and at least do something to attempt to fix the problem, I don't want my engine to expire prematurely outside the warranty period and be left in the cold.

Watch this space.

I would be interested to hear if anyone has implemented the breather pipe delete option...?
 
#22 ·
Hi, I've got an 08 MCS which has all of these symptoms that have been described on here. The car misfired and went into limp mode which prompted me to get mini emergency out to it and take it to the dealership. They mentioned the super knocking error code, and turned out the engine was heavily coked up with carbon deposits.

It was decoked, and then ran like a dream for about 3 weeks until it begun to misfire again, only this time it wasn't just once or twice a day, it would be most times I'd need to use more power. Typically it does it at around 2.5-3.5k rpm, and mostly in 4/5/6th gear. However when I took it back to the dealership this time, they couldn't get it to fault on their test drives.

The next thing I picked up on, is that it is much worse when I'd got a car full of people, so I mentioned this to the dealership and they then weighed the car down with some counterbalanced weights or something. It faulted pretty much as soon as they went to test drive the car.

I haven't had the car since xmas, and it's not doing my business any good either as I use this as a tuition vehicle for learner drivers, and they expect a mcs, not a cooper d.

What I'd like to know, is that this cure of deleting the pipe; Is it safe? Would it affect the warrenty? As obviously, I can't afford to breach that with my job. Any help on this would be very much appreciated.
 
#26 ·
It hasn't been remapped, just a standard job. However, they did say that when they did the decoke, that it was the valve stems or something along those lines that were badly coked up.

I've had a call off them today however to say that the car is having new pistons and a new bottom end. I've no idea what they mean by a new bottom end, but they did say that when they checked the bore sizes of the cylinders, that the 3rd one wasn't right and it looked like a potential manufacturing fault had caused this. I'm no expert on this, but don't get how a car would run for 3 weeks perfectly fine and then play up, if this was a manufacturing fault.

I have pointed out the fix that is mentioned to them and printed off the page to show them, but they say the pcv pipe is clean thus dismissing it as the cause of the fault. Guess I'll see in a few days if this has worked or not.

If the dealership is having problems replicating the fault, see if it's worse when you've got a car full of people and mention it to them, as it exaggerated my problems a lot with the extra weight in the car, and therefore more stress on the engine.
 
#24 ·
Hi this has been happening to me (exactly symptoms at the first post of this thread) with black smoke, on my standard MCS 07 40,000miles
before and after MINI replaced the fuel pump under extended warrenty. :angry:
It was doing it for 6 months and I kept taking it back to MINI (ELMS Cambridge then Cambourne) they kept saying no issue.
finally 3 months ago the chap at the service desk must have got fed up or took pity and said look we'll keep it 2 days take it home with us and try to replicate fault.
They found the fault replaced fuel tank pump (not the other fuel pump at the engine)
And first day back it did it again, to this day it still keeps doing it. :angry:
 
#25 ·
If they haven't fixed it and the fault is still showing take it back ASAP and don't take no for an answer! Perhaps mention the inlet oil theory and suggest they check the combustion chambers with an endoscope for carbon deposits? Don't let the warranty on the work they did expire - I am presuming your car is out of manufacturer's warranty as it's an '07 unless of course you bought the car from a MINI dealer and have the standard 12 month after sales warranty?

Good luck and keep us posted!
 
#28 ·
Guys, this sounds exactly like superknock & there is an easy fix, well it worked for me.

First you remove the engine breather that attaches to the rear left (looking at the engine) of the rocker head cover and where is enters the inlet manifold. Dont worry there is another breather to vent engine pressure on the right hand side.

You fit x2 blanks purchased from Peugot to the inlet manifold and rocker cover. This stops / reduces any more fouling of your inlet valves

Next you can use water sprayed with a hand water spray into your inlet system to remove the carbon off those valves.

There is loads of information on he net on how to do this, so I wont give you all the answers & take the fun away on finding out the exact procedure, blanking cap part numbers etc

It will cost you about an hour of your life, about £3.00 for the blanks and give you back the car you once had.

"R56 Superknock" and "water decoke" will start you off.



Tab
 
#30 ·
Many people have quoted the PCV delete modification, but for you here it is again.
etuners : Technical File


The water de-coke involves pouring water into the intake just before the turbo charger. I used where the the right hand side crank case ventilation hose joins the intake system. Just pulled it off & reattached when finished.

1. Make sure the engine is nice & warmed up.
2. Pour a steady, very very small stream of water. You will hear the engine splutter a bit, so it helps if you have a friend on the throttle to keep the revs up to around 1500 rpm.
3. I found it takes about 10 mins work. Every now and again get the engine revs up to about 4000 rpm.

Take a look here for some idea's:
decoke? - waterinjection.info
very quick q on water method (decoke) - clubgti.com



This is not an exact science, you do this at your own risk but it sure worked for me.
 
#31 ·
Hi Guys,
I have the 175THP in a peugeot 207 GTI in Australia.
I did the PCV delete about 6 months ago and the car runs quite well, power hasnt dropped off as it would normally do after a service.
I do have a small issue with additional engine noise when applying light throttle off idle. This is typically when driving off from a stationary position.
The noise is like a little rattle, i changed the oil with 0-40 fully synthetic the other week and the noise went away for a few days.

I put the PCV hose back in this evening and the noise off idle seems to have disappeared.

Has anyone experienced this before?
I am taking the car in for service with Peugeot again this Monday, i dont want to mention the PCV delete just in case it voids the additional warranty i purchased.
The cylinder head has already been replaced a couple years ago due to coke build up. I've also have the timing chain pretensioner replaced, all under warranty.
 
#33 ·
Whoa, I finally stumbled on the thread of people with the same issue as me! Stuttering at 2.5-3.5k rpm in 3rd, 4th, 5th and knocking throughout (no smoke though). This has been driving me nuts, especially since I'm the only person that can feel the stuttering and hear the knocking!

My PCV hose, spark plugs and ignition coils have all been replaced recently, but still no luck. Mine is a 2007 R56 Justa, so carbon buildup shouldn't be an issue (no direct fuel injection). Also, when replacing the PCV hose, the mechanic had a chance to look in the cylinder, and he didn't see a lot of carbon build up. However, I did see that spark plugs 1 & 4 do have a bit of oil on it.

I'm pretty lost. Does anybody have any new information on this, or other ideas to test?
 
#34 ·
BMW Technical Service Bulletin SI M-12-02-11

Their bulletin mentions an acknowledged hesitation or jerking between 3000 and 4000 rpm

2007 Mini Cooper Electrical System Service Bulletin 317904

Action Number: 10040855
Service Bulletin Number: 317904Report Date: Jul 01, 2011
Component: Electrical System
Summary: Bmw: a software error is causing a hesitation or jerking when accelerating under higher loads between 3000 ¿ 4000 rpm. *rm

My 2007 MCS with 60k on the clock has the same issue. Decoked, new timing chain and fresh plugs (number 4 was knackered) and replaced all 4 coil packs. Still lagging around 3500 revs when mashing on the go button.

I've emailed the dealer about how to get the software updated.
 
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