Hi guys,

New to the forum, thanks.
So, have an '04 R53, 6MT. Just clicked over 162,000km, so as predicted the 100k mile problems have begun.
Have owned the car 4 years, added 25,000km in that period.
I looked at service records, 90,000km, new plugs, 130,000km, secondhand supercharger (I guess the old one was run out of oil?)
Car has been a 1 middle aged lady owner till our purchase.
I fitted a new fuel filter a year ago, I think it was the first one fitted for a long time, as you can imagine, fuel was pitch black and very fine black sand type particles in the filter container.

OK, symptoms are...(coincidentally, a week after a half bottle of fuel injector cleaner added to the tank)
Cold start, crank 3-4 seconds, most times will not fire first go.
Second crank, starts,
10 - 15 seconds normal, then rough running, engine shake and maybe a stall.

I sit there with a wee bit of throttle, so trying to maintain 1500rpm say, the car will drop to 800rpm or less, rough running and engine shake.

1 1/2 to 2 minutes, the car has warmed up nicely and will be OK from there acting normally.

Secondary symptoms, in the rough running phase, black sticky soot out of the exhaust. If revving up to say 2500 - 3000, smoke from exhaust.

My feeling is this is a "rich" fuel mixture that is causing this and the automatic choke or whatever is used by the engine management computer is over supplying fuel or under supplying air.

OK, so videos and reading threads have pointed to a multitude of problem solving eliminations, ranging from fuel pump broken hose to new plugs and HT leads and magnetos to vacuum hose leaks.

I just need to start at the most logical and any guidance would be greatly appreciated.
I have bought a C310+ scanner and there are no fault codes.
I tried some of the functionality to monitor engine whilst engine is running.
Where would I want to look to feedback values to you guys that may help with pinning down the problem?

Any ideas guys?

Thanks
Tony

 

I am having trouble with starting the car when it is not warm as well. I started with the cheapest thing, and I am slowly working up to the more expensive ones. I cleaned the throttle body, changed the belt, spark plugs, wires, coil pack, and fuel filter. I have also ran it over 4,000 rpm on the interstate to try to burn/clean out everything. I have the same opinion as you, the car seems to run too rich most of the time. It sounds like you might have loosened a reasonable chunk of carbon.

 

Lets hope we find the problem.

I'll take her for a thrash over 4000 and see if the carbon goes.

I have some new plugs coming.
I have also been told my problem may be some corrosion in cylinder 1's water jacket and it lets a fraction of water into the cylinder after being sitting a while.
I've got a borescope coming and I'll have a look down the sparkplug hole after an overnight.

Will keep you posted, good luck.
T

 

I have seen a lot of people on multiple forums talking about having to replace their fuel pumps. I have been considering that as well.

 

My gauge can tell me fuel psi. If yours is low/inconsistent = bad fuel pump. Very easy DIY. Bought my fuel pump from Neobrothers. I have the Ultragauge. Well worth £100.

 

Mine doesn't have a fuel PSI gauge. I did take the fuel line out after sitting all night, and had no fuel pressure at all in the fuel rail. Therefore I know the pump isn't holding prime on the line anymore. Cleaned the fuel injectors with carb cleaner, and started added half a bottle of Lucas octane booster to each tank of gas. It has helped some, until I can buy the fuel pump from rock auto.

 

did you ever solve the problem my car does the exact same thing

 

I ended up having a bad fuel pump, and bad fuel sending unit. Also, I had to disconnect my antenna power wire on the antenna amplifier, because it had a constant voltage of 0.40 volts regardless if the car was on or off. These three things are what fixed my starting problem.
From what I understand minis run rich to begin with. It sounds like you could have a vacuum leak. I had to rep[lace the hose on the back side of the throttle body, so that might be good place to start. Another spot to check is under the supercharger horn on the passenger side is a connection that likes to fall off.