Car:
2009 Mini cooper hatch, automatic, no frills. 76000 miles.
Problem:
Acceleration falters badly, loses power at 2000 rpm (+/- 200). If I just ease on the gas at that point, the forward motion is very 'joggy' and the revs dont go up until my foot passes a threshold and, it eventually downshifts, the revs go up to 3000+ and all is fine, the car accelerates.
This problem is absent when the car is cold, but starts to happen consistently after 5 minutes of driving.
Only twice in the past month has the engine light flashed on, and then it went off right away.
Known issues:
Thermostat housing has been leaking for a month to the tune of half a liter of coolant every 2 weeks or so. I had it changed 6 months ago by a private mech who's no longer around. Just prior to that it leaked profusely.
Battery is very old, still original
Dilemma:
I need to keep the car running safely for a few more months while I take my time looking for a new vehicle to accomodate a growing family. Then I'll trade in.
History:
A month ago I took the mini to a new mechanic to change the VANOS solenoid in order to clear the error code and pass DEQ. He informed me that my Thermostat housing was leaking (again!) and insisted that if I didn't change it, my car would collapse on the road in the next few days. Having just been through a leaky part, I didn't buy his pitch. When my housing was dripping puddles (6 mo ago) there was no effect on acceleration only over-heating issues. The acceleration problem has gotten noticable worse since I took the car in. I just changed my air filter, but no help.
Solution:
My thoughts would be to change the fuel filter or maybe clean the injectors, both of which I can do at Jiffy Lube for not too much.
Does this sound like it might help my problem?
I first though that this might be spark related, but a missed firing would cause a fault code, no?
Any other suggestions for low cost quick fixes that might help?

Many thanks

 

My car, very obligingly, just gave me a check engine light that stuck. I just went to Napa to read it: P0304. A firing fault in cylinder 4

 

1) When were the plugs last replaced? If they are original they are due to be replaced.
2) swap the coil on cylinder #4 with another cylinder. If the misfire code moves to the other cylinder then you need a new coil.

 

Re #1: I had plugs and coils changed out at, I think, around 40-50k. Whatever the official mini service recommended.

Re #2: Thanks, that's a good first thing I can do! Now I just have to find one of those crazy 12 point sockets that I need to pull the Mini Plugs

 

Oh wait, I wasn't thinking...I don't need to pull the plug to swap the coil...

btw Can I use a more standard socket to pull mini plugs?

 

From my other (repost) thread...
1) Would the battery really play a role once the car is running? Doesn't the alternator take over?
2) The coolant leak is definitely from a crack in the thermostat housing.
3) "
4) Yeah, I'm double guessing myself as to who I trust with my car
I figured Jiffy would at least be able to handle swapping the fuel filter without inviting disaster. I might do it myself but by the time I buy a strap wrench and a pump siphon, it might not be worth the hassle.

 

Fuel filter is in the tank under your rear seat! Please don’t go to jiffy,,,,,,,,,,,,��

 

Cooling system problems will affect your car more than you would believe; from hard starts to no starts, rough idle, poor economy, misfires, etc. I would recommend fixing the thermostat highly, but if you say you did spark plugs about 30k miles ago you may be due again. For whatever reason the Coopers seem to devour spark plugs in around 30-50k miles, which is about half the life that the manufacturer rates them for.