Hesitation/Stutter on over-boost/full acceleration

[dave_beast]

The problem is the PCV rear pipe

Quote:

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

[noisybrother]

Quote: Originally Posted by dave_beast (original)

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!

[noisybrother]

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!

[noisybrother]

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?

[frashed]

*Bump

Did you solve the issue? I'm having the exact same problem at the moment on my 07 MCS. Any help would be much appreciated.

[noisybrother]

Quote: Originally Posted by frashed (original)

*Bump

Did you solve the issue? I'm having the exact same problem at the moment on my 07 MCS. Any help would be much appreciated.

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...?

[Dunny]

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.

[htspike69]

sounds like valves or air/fuel mix ratio. is it remapped ?

[tyler b]

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.
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.

[noisybrother]

Quote: Originally Posted by tyler b (original)

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.
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.

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!

[Dunny]

Quote: Originally Posted by htspike69 (original)

sounds like valves or air/fuel mix ratio. is it remapped ?

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.

[mattblackbrough]

I bought some Seafoam off Ebay and did 3 treatments through the PCV hose over a month period. Seems to have resolved the hesitation and possibly the metallic noise, at least I haven't heard it since the final treatment anyway.

From reading around its down to the carbon build up in the direct injection engine.

[Tabintab]

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

Quote: Originally Posted by mattblackbrough (original)

I bought some Seafoam off Ebay and did 3 treatments through the PCV hose over a month period. Seems to have resolved the hesitation and possibly the metallic noise, at least I haven't heard it since the final treatment anyway.

From reading around its down to the carbon build up in the direct injection engine.

[Clifford clubman]

Looks like a great fix to me, but please can you tell us more or show us some pics of the fix. I've been searching the web for more details with little success.

[Tabintab]

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.

Quote: Originally Posted by Clifford clubman (original)

Looks like a great fix to me, but please can you tell us more or show us some pics of the fix. I've been searching the web for more details with little success.