I hope someone can help me with this problem.
I have an 05 Mini Cooper S and it has started giving
p0300 (multiple misfires). but only at startup or within
20 to 30 seconds of startup. I have replaced all the
plugs with new NGK plugs, new plug wires, and a
new factory coil pack. I have also run 4 or 5 bottles
of injector cleaner within the last 2,000 miles. Should
I start replaced injectors, or the fuel filter? Anyone
have any ideas where to procede. Thanks for the help.
Perry

 

There's basically 3 reasons why a cylinder misfires;

1. Loss of spark(which you've addressed)
2. Air/fuel mixture too unbalanced to ignite
3. Loss of compression

A bad coil would usually affect all cylinders so try to narrow it down to whether it's just one cylinder or all of them.

The lean mixture could be caused by an inoperative fuel injector(whether it be clogged or just plain worn). See if you can get a voltage reading on your injector(no voltage reading means it's dead). A dirty filter or leaky pressure regulator could also be a cause(air side of the equation).

The third reason(loss of compression) could be caused by a leaky exhaust valve or a blown head gasket. Is your engine overheating or have you noticed an increased need to top off coolant? If so, blown head gasket would probably be the issue.

To isolate the misfiring cylinder, you could disconnect one spark plug at a time at idle. When the idle speed stays constant, you've found the misfiring culprit. By the way, how was your old spark plugs? What did they look like?

 

I'm sorry I wasn't as clear as I might have been. This code
comes up only as start up or shortly after 20 or thirty seconds. The engine does not continue to misfire but runs
fine after giving the code at startup. I can clear the code
and it may not come back for days, but it does come back.
I didn't think of compression but thats easy enough to check. What should the compression be? I have had to
add coolant maybe twice in the last year. By the way
this mini s has approx 98k on it but runs ok otherwise.
Also what would you think about a fuel filter causing this
problem. Thanks for your help.

 

It sounds like something's being clogged up periodically and once enough air/fuel moves around, it clears up. A bad fuel filter will generally be more constant-generally at every start up. Then again, fuel filter changes isn't hard so it might be an easy one to just check off the list.

140-160lbs is the normal compression for most engines and it should be pretty constant throughout every cylinder(I believe a 10% difference is allowable). I would also check injectors to make sure they're not clogging up but at the same time, a clogged injector would be a steady misfire.

 

How do you change the fuel filter on an 05 mini cooper s?
Also when manually cleaning the fuel injectors on the "s" do just remove the top of the turbo charger to gain access to the fuel injectors? Thanks for all the help.
Perry

 

Not sure about the injectors since I have a non-S 2nd gen. As for the fuel filter, pretty straight forward;

https://www.northamericanmotoring.co...ol-filtah.html

That link even has pictures of how to do it. :D

 

I've an 06 R53 and the same code... OBD2 reader gave me:

Calculated LOAD Value 40.00 %
Engine Coolant Temp 195.80 °F
Short Term Fuel Trim - Bank 1 0.00 %
Long Term Fuel Trim - Bank 1 1.56 %
Intake Manifold Absolute Pressure 14.51 inHg
Engine RPM 4,812.00 rpm
Vehicle Speed Sensor 73.32 mph
Ignition Timing Advance #1 Cylinder 46.50 °
Intake Air Temperature 105.80 °F
Absolute Throttle Position 25.10 %

So based on 14.51 inches of mercury that = 7.12 psi, that's really low right?

The car's gone schizo on me. Sometimes running fine, then all of a sudden feels like i'm on 2 cyls and the car's got a cough at 120 bpm, and the revs won't go past 4100.. On the upside when this happens comp. shows 99.99 mpg ... Though I doubt that's what happening. I'll have the dealer take a look tomorrow, but Perrry, what happened with your car?

 

I know I'm a little late to the party by 6 years or so, but I have a 2009 Mini Cooper S with the exact same issue. I'm curious what happened to Perry and Dua's Minis. Were you guys able to track down the issue?

 

Since it's been so long I doubt they will come back with an answer. As a suggestion, check this site for recommendations on P0300 - http://www.obd-codes.com/p0300

Also, I'd maybe focus on injectors and possibly the fuel pump. It does sound like it could be a fueling issue. I'd also possibly perform a compression test to see where you stand. What diagnostic work have you done so far to track down the issue?

 

There has been some focus on the Gen 2 MINI S : 2009 R56 MINI Cooper S that its linked to the HPFP on its way out .

https://www.northamericanmotoring.co...r-r56-jcw.html

 

While I no longer have the 2005 Mini Coopet S , I finally did get the p0300 code resolved. The problem
was a groove that was worn into one of the cams. Occasionally the cam follower would drop into this
groove causing the engine to misfire and throw a p0300 code. I had the camshaft and the follower
replaced and no more p0300 code. You can diagnose this problem by removing the valve cover and
closely examining the camshaft surfaces. Hope this helpful to you.

 

thanks for the update on the 2005. How bad was the grooves. Where they on every lob.

 

The groove was only on one lobe and was probably cut by a frozen follower roller. The groove was about
3/16 of an inch deep. This was four years ago I think thats correct. The engine ran great but when the
follower would drop into the groove the valve would not open correctly. I never had the problem again
after replacing the camshaft and follower and the car was traded at 160k with no engine issues.

 

Yea, i was going to say its rarer to have that happen. Have 260K on my 05 MCC and never had a cam issue. Thanks for coming back with the update, even though you no longer have it, helps out a bunch on what went on.

 

Another nail in the coffin for those who decry the evils of opening old threads. Sometimes they produce answers.

 

I've had this exact issue for a few years on my R50. The dealer and Fat City European Auto Repair could never figure it out. The previous owner of the R53 I just bought said he had this problem, and a local shop figured out it was a small head gasket leak, and it resolved after replacing the head gasket.

If you remove the valve cover, a 3/16" groove in a cam lobe should be easy to spot, no?

 

Do you have a pic?

 

well good morning all, not so good for me. as i was driving to work this morning in the middle of highway at about 85miles an hour it happened sudden loss of power and misfire but the car was costing so i checked my scangage and there it was P0302 and 304 so i very carefully drove the car to work and switched the coil packs around and 302 went to 300 i hope its just a coil pack since less than 1800miles ago the head was rebuilt due to smoke from exhaust and bad valves seals.
last night as i was driving home i had this incredible power with the car and i thought i was driving in sport mode kept pressing the sport but did not feel any different so i thought i am stuck in it, this morning the car started as usually dose but within 10min pooffffffff.
i will be changing coil and new set of oe plugs to see if it will work since switching coils moved the code.
now another though, few hundred miles a go i had my oil change done and as i check my oil level every few hundred miles i saw that the oil on the stick was way above indicator could that be the problem.
thx
Ben