MINI Cooper Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
26 Posts
Discussion Starter #1
Can anyone help with diagnosing this issue I have which appears to occasionally come on around 1,500 to 2.000rpm.

When I'm driving at to maintain a constant speed (ie motorway 50mph enforcement) after I've let go of the pedal to manage it and then re-apply the gas I get a slight hesitation/flat spot as if it's a fuelling issue. It doesn't seem to happen at 70mph+ speeds or lower than 45mph and take off/acceleration is fine which tends to rule out fuel starvation?

I had a pal pull the fault codes and nothing has shown up but I'm leaning towards the MAF sesnor being faulty? It's a definite flat spot rather than a blockage I think. I've tried fuel additive to clean the jets etc but no change.

Any ideas please? 2015 Cooper SD full service history by Mini on 50k miles
 

·
Registered
Joined
·
7,414 Posts
EGR valve or dpf getting full the dpf , if dpf try this go on a run on motorway for 30 minutes at 3000 revs this will force heat and pressure in to the dpf filter it will also clear out any soot in the vnt on the turbo it will also help to clear the egr valve as well,, if this improves it then you know your on right track, might need to clean egr off the car or replace it if faulty .. a diesel mainly used around town could block dpf filter to a point wont regen within your mileage its very possible,, you could have dpf pressure sensors up on live data see what the pressures are before and after the filter it will also show last time a regen was started if only done the last time driven chances are it needs cleaning or replacing
 

·
Registered
Joined
·
26 Posts
Discussion Starter #3
I don't think it will be DPF as the car is mainly used on motorway journeys of at least 90 miles continuous around 60-70mph. Within 2miles of either end I'm on the motorway from cold. Having said that the stop/start has not operated for a long time and perhaps because I don't use it in city driving conditions?
 

·
Registered
Joined
·
7,414 Posts
if there are any hidden fault codes within the ecu start stop will not work also it will prevent the car from doing its own regen to dpf filter so need to scan first off prob find some answers within it live data runs on the boost pressure actual and prescribed also fuel rail pressure and injector fuelling's ie can see what each injector injects mg/s , all within diagnostic can see the difference in pressures before and after the dpf filter, could spend weeks trying to find what is going wrong without a diagnostic tool that will do everything and there's not many around cheap that will .. bmw software insta d complicated to say the least,, better one to use and i use one all the time is autocom cdp plus they are on ebay for under £50 load on a laptop and look for the one that shows the double green circuit board as these are full function the single circuit board ones are not very good, another good one is wurth snooper the RAC use this and will cover most things but the live data is a bit hit and miss, i have both and have link them both to same vci works a treat i can switch between the two softwares,, this all said diagnostics give the first place to start looking and dont always mean its the component at fault, ie flags up a cps sensor sensors a fairly good dont fail much to me thats a indicator of timing chain perhaps, had a diesel one not so long ago it flagged up boost pressure and map sensor,, turned out the oil pump chain had broken and lack of oil pressure caused the turbo to drag on its bearing and the map sensor was working seen the boost pressure was low, the n47 diesels are know for timing chain stretching i would always check the timing on diagnostics for piece of mind
 

·
Registered
Joined
·
7,414 Posts
Thanks Mike, yes a diagnostic check looks to be the way forward.
below link is best for money really is a good tool i've had mine for over 6 years now used the hell out of it works on any car can code and do all kinds and works with all the ecu's etc on some cars can add keys if have soft code numbers for new ones , the one in this link has the green double layer circuit board its important to buy one like this as other without will only read and not code write as well
 

·
Registered
Joined
·
26 Posts
Discussion Starter #7
Just to update this thread. I got the car scanned by my local garage and it's flagged up a fault with the 'EGR Valve Excessive Flow'.

He cleared it to see if that solved the problem. It hasn't as it's just come back so I presuming I will need a new unit fitting?
 
1 - 7 of 7 Posts
Top