Hi guys im wondering if anyone can help me on here with the problems im having with my 07 Cooper s.

Im from the UK but im struggling to find help on the UK forums as nobody has had a similar problem to me.

Long story short i recently bought a 2007 cooper s that took about 4 seconds to start hard or cold and also was low on power until 4000 rpm. After 4000 rpm when the turbo had spooled up it was fine.

It was believed that carbon build up may be causing the issues i was having. I removed the inlet manifold and cleaned the ports and reassembled everything including changing a vacuum hose. The car was exactly the same except that after i drove the car for 2 minutes and switched it off i lost all turbo completely. I had absolutely no fault codes either.

I didnt have time until today to look at the problem so i drove almost 400 miles in the car with no turbo boost and it still didnt throw a fault code.

Today i removed the intake manifold again, I then cleaned the ports till they were like new. I also changed the diverter valve on the turbo and also the spark plugs for the sake of it.

Again the same ting happened. The car had power again above 4000rpm till i turned it off and then it went back to having no boost again.

I have 3 questions.

1. What would cause the car to take 3-5 seconds to start (hot or cold)
2. What would cause the car to have low power under 4000rpm.
3 what could be causing my lack off boost.


I have even run a vacuum hose from the vacuum pump straight to the actuator (which does have vacuum) but it makes no difference.

 

Your cylinders compression could low taking even longer to build-up compression, this might explain the long start-up. Have you removed the turbo charge pipe to check for shaft end play? At this point you need to start the process of elimination by eliminating a long list of potential causes.

 

Possible pressure conventer or tank air vent valve failure? Proplems with boost pressure handling often due the vacuum control proplems, broken pressure conventer is sometimes hard to find, mechanically bad but elecronically ok! No Cels.Leaking tank air vent valve loose boost pressure to fuel tank, I do not know, how to influence the poor start -up....

 

That's exactly what I was thinking. I will order one from bmw tomorrow. In regards to a compression test I will do one tomorrow as well. My turbine wheel spins freely and has no play.

 

The turbo diaphragm actuates the wastegate when a vacuum is applied. So, when you connected the vacuum pump directly to the actuator, you opened the wastegate, removing any possibility of boost pressure. If a vacuum is at the diaphragm continuously, with OEM hose connection, your "pressure converter" is probably shot. This "pressure converter" is just a valve that opens on ECU command, to apply the vacuum through a reservoir tank to the diaphragm. My after-market turbo doesn't use this vacuum system, so it's completely disconnected --- no CEL's either!

Now, if your "pressure converter" is stuck open, or somehow allowing vacuum through, this could very easily be your "no boost" problem. The hard starting and low power might be the ECU response after "learning" about an open wastegate. Might also be a completely different problem. The ECU can be reset to remove "learned" activities.

 

I believe that the cooper s uses an unusual waste gate system where vacuum holds the wastage closed and not the other way around.

 

Sounds like two different problems. Starting issue is probably either fuel or spark related. My guess would be fuel. HPFP or injectors. The turbo problem sounds like either a sticking N75 valve "boost converter" or a broke recirc valve. It's really strange that your not getting a boost deviation error though.

 

Yes, it is an "unusual" system. Most other turbos use positive pressure to activate the wastegate. Mini Cooper is an exception. Here's another thread where someone is asking about adjusting the wastegate. It might help you understand WG operation. https://www.northamericanmotoring.co...-question.html Also, my WG vacuum source measures a constant 20 - 25"hg. Pretty easy to measure if you have access to a vacuum gauge and a "tee" fitting.

Please don't take this as an insult, but, you're the one asking for help! My OEM turbo is on my workbench, and I'm intimately familiar with its BASIC operation. OEM wastegate is activated (opened) with vacuum, not pressure!

Tigger2011 is correct about possibly multiple problems. Resetting the ECU is just one more possible solution.

 

Sorry to hijack but can anyone please advise how to reset the ECU to forget "learned" functions.

 

if that checks out, some other spots to take a look at, your intercooler it could be gunked with oil, oil on the map sensor, throttle usualy in open but also gunked closed. When cleaning the intakes do the charge pipes.

It is a mess under the intake tripple check your connections. fix the crank case breather mess while you are at it. Possible Mann provent 200, saikoumichi catch cans with mesh.

 

I use my AccessPort --- it's a built-in function.

I've read on different threads that disconnecting the battery will reset the ECU. 'Course, that will also reset a variety of other things. Try the various parts houses that read codes. Maybe they can reset it for you.

 

Right in regards to my ongoing issue. I have a friend who has dedicated BMW Diagnostic software that should hopefully see something my snap-on cannot.

I had a good browse around yesterday and found a small crack in the pcv pipe that runs form the rocker cover to the Inlet manifold which i will be ordering tomorrow.

I believe the hard start is definitely fuel related but i have no normal HPFP issues so it may be the in tank pump.

 

That leaking "PCV pipe" could also be the cause of your other problems --- it's a direct connection to manifold vacuum / pressure. You might want to fix it BEFORE working on the other problems.

And, the ECU will definitely "learn" about that leak, and make corresponding adjustments. I had a similar "learning" issue when a hose came loose and I lost boost. Gotta love that AP!

 

Just thought i would let you guys no the lack of boost was the fuel tank pressure valve and the lack of power under 4000 rpm and hard start was the timing chain.

 

Happy to hear that the fault was found! Including additional "data" in the forum is always good !!