Looks like mine has been starting better in the cold... Don't get it.

 

We are going through a heat spell 80s here and its been hit or miss. I will have to see how it gets when its cold

 

The valve guides that were in my 02 MCS were weak. It was a common problem with the guides that they used and they were prone to failure.

 

Oh ok gotcha, so is yours performing better now that that is fixed?

 

Spark plug wires!!!! I had same issues. I thru a ton of mods on the mini.intake ,intercooler,pullies,exhaust.and more..and then the car would bog or hesitate.i pulled out all kinds of things for weeks,bypass valves intake tubes. Everything..and you know what it all came down too?? The new ngk wires i put it when i first started modding it.about a month ago.i swapped them with my stock ones on a hunch that maybe those new wires sucked and were breaking down under aload..the car is a totally different car now..no bogging and tons of power..

 

So are you saying you are currently running the NGK or stock plugs??

 

Hi. Im running the one step colder jcw ngk stock plugs..the new ngk wires were the problem...using the stock mini wires now

 

That is interesting, I might have to try this myself since I am not running stocks either right now. Do you have a stock coil pack as well?

 

Fuel filter?

 

Already changed that on mine and nothing

 

Vacum....vacum...... Check all vacum lines..especially one on left hand side of intercooler underneath other lines above intake

 

Ill check those out too thanks!

 

Hi. Theres a line under these lines connects to port on thr intake.it can come off when the rubber connector wears out. Take . Look closely under those lines

 

Hmmmm interesting ill check those out too.

 

Look underneath those lines for the one im talking about

 

Ok Thanks!

 

Well everyone, I figured I may as well follow up on here, being the OP. What I have learned since starting this thread is......ANYTHING can cause this. Most typically, It's probably a vacuum issue. Our cars have SO many potential places to not seal properly along the air intake tract that this will probably be the issue 8/10 times.

The thing is, after replacing my head gasket, I have been troubleshooting the same cold start / sputtering issue with no success. I know my original issue has been resolved (coolant slowly leaking into cyl. 2, not allowing that cylinder to fire properly for the first bit after the car had been started).

Now, my car does not quite pull the vacuum that it should, idles rough/loudly and occasionally bogs & dies when letting the RPM drop. Instead of consistently resting at 800rpm like it should, it will dip to about 500, slowly pulling itself back up. Or, it just won't catch itself at all and fall to 0. It struggles to start just about every time as well.

I have:
-had it smoke tested.
-built a pressure tester PVC cap / air compressor system & got it the whole system to seal quite well.
-replaced the BPV with a Detroit Tuned unit
-replaced the plastic intake pipe
-replaced the green gasket twice
-replaced the MAP/TMAP sensors with known good units
-simplified the vacuum system as much as possible, taking the JCW air intake hose and oil catch can out of the equation

Now I'm reading that a failing fuel pressure regulator could cause this, but I think I'm done throwing parts at the car that may or may not fix it. It honestly runs GREAT on boost / open loop, but man o man it hates to start / idle / run in closed loop. At this point I'm thinking I'll take it to a Mini shop & see if they can diagnose just what the hell is going on. I've never been this stumped by an issue on a car. I will ABSOLUTELY report back on here once it's all figured out & let you know what I find!

 

WOW, thanks for letting us know and keep us posted. Good Luck

 

Alright, finally threw in the diagnosis towel & took it to a shop. They found every cylinder to have low compression (around 130), either meaning my timing is off or I managed to bend a row of valves, depending on just how much of an interference design the R53 motor is. Going to start a new thread about this entirely, as I feel it goes beyond the original scope of this thread.

On the other hand, despite my engine having more serious issues, obsessively sealing up the intake tract has enabled it to run fairly well, even in it's current condition. There is a thread somewhere on NAM that talks about making a PVC plumbing fitting w/ a male air compressor fitting, pressurizing the intake & spraying soapy water everywhere & look for bubbles. Using this method, I found leaks at two of my supercharger inlet seams, my BPV diaphragm, both BPV hose clamps and that terrible green inlet gasket. After sealing all those up, the car is totally drivable despite the more serious issues.

Our other R53 was having some sputtering issues on startup & a new MAP / TMAP sensor totally resolved it. I will be doing the 'ol soapy water test on this car as well, as I believe that is the best place to start with these issues.

 

This is getting really interesting now, please attach a link from this page to the new thread. And good luck!

 

Cold start problems like many of you. My wife has a BMW X5. Had similar problems. Follow me on this as my moonlighting Audi mechanic fixed the X5. The rubber boot for the intake that looks like an accordian cracks (often in several places) in the bendable part. This messes up the fuel/air ration and in my mind the MAP sensor doesn't compensate. When you first start the car there is either too much fuel (from setting overnight) or air being sucked in through those cracks. Until the car starts the fuel/air ration is off. What my mechanic showed my on the X5 is to put RTV goop in the cracks and wrap with electrical tape until I could put a new boot on. Well, well, seems my Mini "whistles" when I get it running. I looked at the boot (180K miles) and it has several cracks. I haven't replaced it yet ($100 - Bavauto) but my hunch is that once these cracks are gone the engine will start normally. I'll report back, but look and seek if your rubber boot has cracks in it. Just a small one will upset the ratio. Our babies are finicky.

 

This is very interesting. Please let us know if the new boot will fix this issue. I looked the other day and I have a few small, and one very large crack in my boot as well.

 

I have a new intake tube....It did not help. I hope it helps on yours.


Sorry to mess with your good theory.


Anybody with this problem have any boost fluttering at partial throttle? I have a 2006 MCS

 

Does anyone know if a replacement CAT Converter would cause this issue?? I had ANOTHER problem today with my car..... I am done after this fix, its up for sale! Another Barnaby issue arose today... Was cruising on the highway around 75-80 mph for about 1hr and got off my normal exit and my car lost all power. Check engine light came on and the dash lit up. I threw it in N and coasted into a parking lot. Plugged my OBII reader in and no CEL but minor o2, EVAP, and CAT sensors were lit up red. I had it towed back to my house. And tried to start up, had a cold start and then died again. Now it wont start at all. HELP!!!
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