Hi, ive just purchased a mini cooper 2003 john cooper edition (cat back exhaust syastem i think)
It has a hesitation \ lack of power \ misfire when you floor it from about 20mph in second untill about 55, then it really starts to pick up and go.
SWame in 3rd gear its missing between 1500rpm and around 4500rpm
its struggling to get from 65 to 75 in 5th. it just seems to be really lacking power.
The car idles fine to say it has 91000 miles
Since i have had it ive flushed the fuel system throught with redex all with no change!
I took out the spark plugs yesterday to find they were very worn the probe in the middle was very worn, colour was fine as it should be across all cylinders.
i have fitted new spark plugs today expecting it to solve it but with no luck!!
The car has had a new gearbox in the last 15000 miles.
Any help would be really helpful as id love to get it sorted as the rest of the car is great just the lack of power and jerky ride
A coopers power only really comes from about 3800 rpm onwards and runs out around 5500 is this what you are referring to?
Have you had any fault codes from the ECU or the check engine light (SES) come on? If it was misfiring you should have had a code but not necessarily. I have heard of the oxygen sensor causing some problems with power as the air fuel mix isnt right - but this should cause a generic loss of power across all rpm
I would try resetting the ECU and see if this helps and also check the air filter is not clogged.
To reset the ECU - hold the mile reset button on the speedo down for a few secs then move the ignition key to the 2nd setting - the text will change from total miles to the menu - keep pressing the button to cycle through until 19 then when it flashes from Li on to Li off press again and your in the system - then cycle to 21 and then press reset and the ECU will reset The dials and lights go weird and your done. The ECU will then have to relearn your driving style and adjust its settings accordingly
Update, thankyou for the info provided i have done as suggested and reset the ecu, unfortunatly it made no diffrence, i have no warning lights and may well book it in at bmw to get the fault codes read unless there is another way to do it?
I have took offf the throttle body and air mass sensor and cleaned them all out there was no problem withj these a little coked up but not enought to make it run badly
Its more of a lack of power than anything any more ideras people|?
Regards injector cleaning redline S1 is one of the best to try and clean injectors and valves. About £6 from fleabay. Much better than redex which is essentially naptha.
Worth checking cylinder compression across all 4 cylinders - should be above 200 for a cooper
I would recommend finding a sponsor or a decent mini independant garage with some common sense rather than BMW - it will likely be cheaper (£110/hr labour rates at BMW mean minimum spends are around this for diagnosis) and more productive especially if no fault codes are displayed. A decent OBD reader can be had for under £100 and tranferable to any other vehicles you get in the future. Many members like the scanguage II as it monitors as well as reads/clears codes. It is not the best code reader however but a very versatile tool
I assume the 200 DrNorman is talking about is in psi, are you sure your figure is 100kpa? that works out at atmospheric pressure (no compression at all!) in all the cylinders, which would suggest something tragic like a timing chain failure that has bent all the valves, which is quite rare and obviously the lack of power would be VERY apparent!
If it is 10 bar, or 1000kpa, that equates to around 145psi... which is not the highest I have seen, but not the worst either, certainly not likely to be causing a misfire and I would not expect you would experience it as a major loss of power, although it may not feel quite as nippy as it was when a year or two old.
If you meant 100psi then that is rather low, and it would definetly manifest as a lack of power.
However, the correct way to carry out a compression test is to remove ALL the spark plugs, and only carry out the test at cranking speed, not idling speed... your figures may be artificially low as the piston speeds would be to high and the manifold pressure too low... I dont know for sure... I never tried testing the compressions on a running engine before!
I would recommend checking them again correctly before making any rash decisions.
"Allow me to explain... Understeer is when you hit the armco going forwards, Oversteer is when you hit it going backwards!"
A couple of things come to mind when a car gets to be this age. Time to replace the oxygen sensor (but you should get an engine code indicating that) and time to replace the fuel filter (which there is no recommended replacement schedule for).
Since you say you get a hesitation when you accelerate, I would check out the fuel filter. Fair warning, the fuel filter for our MINIs are fairly expensive to replace, but you don't do it very often.
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Alta 22mm rear anti-swaybar, Madness CAI, Alta 15%, NGK BRK7EIX, M7 Strut Tower Reinforcement plates, BSH Lower Engine Mount
hi, ive retested the compression in the correct way remoiving all plugs and testing at cranking speeds!! the pressure was at around 7 bar (100psi)
still low i know!! is it lickley to be worn piston rings?
as regards the fuel filter it has crossed my mind and i have thought i wonder what the interval is....
its booked in at bmw on saturday for a bit of diagnostics
so basicly im running 100psi which is very low but ovb enough to run, as regards it picking up at around 45000rpm does this add up would it have jigher compression at higher revs?
I am afraid it does sound something like piston rings, they dont last long if they have been allowed to run on a low oil level, which sounds much more plausible to me than just wear and tear... 91000 miles is not alot for a well maintained MINI Cooper... I service one for someone that has twice that and its fine!
If you are lucky, it will only be the rings that are worn, but in my experience, the pistons follow soon after the rings as the worn rings rattle around in the ring groove in the piston and wear them out, needing the pistons to be replaced at the same time. From memory, a set of rings are around £100, but I have never had to buy them on their own as I always needed pistons, and they come with the pistons.
With regards to the engine picking up at higher revs, its all to do with speed against torque, the higher the piston speed, the less low compression will have an effect, within reason, as there are more 'bangs' (power strokes) a second to 'share' the load and therefore the drop in compression is less noticable to you... but it will still be down on power.
To fore arm you with prices for when/if BMW try to take your trousers down!
I replace pistons and refresh engines for our race cars (everything in them has to be standard) and the pistons are the expensive bit, as, I said, they come as a complete set, about £650ish (Ihave seen sets on the internet for £400 but we cant use them, so I dont know what they are like), but then you have to buy bearings and all the gaskets/seals involved in the job, roughly, you are talking about £1100 on the engine alone, so long as the block is not damaged, which is not likely unless they ran it dry for a while.
You can get a second hand engine from a breaker, or an 'e-bay special' for around the £500 mark, I have seen them sell for less, but never risked it.
Obviously doing your current engine is the more expensive route, but at least, if done right, you will at least know you have a good engine that will be good for at least another 100,000 miles... with the 'e-bay special' you really dont know what you are getting... despite the breakers claims that the engine has only done 20k, there must be loads of MINIs scrapped with 20k on the dials!
In either case, you are going to have to pay someone to remove then refit the engine. It officially should take 6.1-6.35 hours, depending on extras fitted (our record is just under 2 hours, using 2 men). At dealership prices you are staring at the wrong end of a £600+ cash transaction for that bit alone, then there is the initial diagnostic and anything else that crops up, clutch replacement, likely at 91000 miles, etc. Also, dealers are less likely to go down the route of supplying you with a second hand engine, opting for a BMW recon. unit... a steal at around £2500!
My recommendation is the independants route where you should find someone to do a replacement engine job for around the £800 to £1400 mark, including supplying an engine.
My Guesstimation (using past experience of the race cars)-
£1650 all in for engine refresh
£950 for a replacement second hand unit
Hope this helps
"Allow me to explain... Understeer is when you hit the armco going forwards, Oversteer is when you hit it going backwards!"
I think it is too prevalent a problem in Mexico under campus forum yesterday as my car three sensors simultaneously (ASC + ABS + tire pressure) but only with a difference that the car handles in perfect condition!
Someone who would help me in knowing that my car has a problem, some experts?
thank you very much
Yeah the values of compression for a cooper should be 200psi Upwards. They have the same engine block and head but the S has lower compression ratio as it is supercharged and has convex pistons to compensate for this extra pressure.
As C.Noble quite rightly says be wary of BMW as costs will soon spiral > I wouldnt be suprised if on saturday they do a compression test and fault code reading and charge you an hours labour rate ie 110 pounds and suggest a further few hours of diagnosis.
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