hey guys,

my 2007 MCS Auto was experiencing what I believed to be the first symptoms of the fuel pump failing. Hard starts after sitting overnight. And very poor accel (stuttering badly) before the car got fully warmed up. Once warmed up, it seemed to all be fine. Did have multiple misfire codes too. I live 2 hours away from the mini dealership and decided to bite the bullet and drive it there for inspection. I was praying that it was the fuel pump because its covered under the extended warranty.

So the dealership just called and told me that its not it at all. Its a bad thermostat, and the battery has dead cells. I'm hesitant to belive that this will fix the problems that i've had. But can anybody chime in and help me either way.

Another problem that I've had has to do with boost cutting out under very hard accel. On hotter days, when I go to pass somebody on the highway and i put the pedal all the way down, it pulls hard for a second then it just totally looses all boost. It takes about 30-60seconds of feathering the throttle to regain the boost, but when it comes back, it comes back all at once WOOOOOSH!. Would a thermostat be causing this as well? I have Alta intake, exhaust, and a perrin BOV all installed by the previous owner. My car might be chipped (alta?) but I can't confirm that either... really no way of telling?

Finally, with the battery - can i just replace this myself? or will all kind of crap be locked out on my car if i dont have it changed by the dealership? Reason i ask is because my brothers BMW 335xi needs to be changed by the dealer "or else"...

Thanks guys, all help appreciated. Dealership wants $500 for thermostat and another $210 for the battery. NOT in my budget right now.

 

Thermostat.... nah! You'd have performance issues related to the coolant system if your engine coolant temperture (ECT) sensor was bad since the combustion strategy is partly based off engine temperature. If the electronic thermostat was bad it would fail in the stuck open position and the car would take a long time to warm up, you'd have a CEL for that, and that's it.

I would get rid of the stupid BOV. You're just asking for problems with vent to atmosphere blow off valves on the R56. The problems you describe with sudden hesitation are textbook cases of your ECU not liking the vented boost air. I've been through that phase so I'm talking with experience here. I hope your car doesn't have a block off plate where the electronic diverter valve should be on the turbo. For the car to work correctly you should have the OEM diverter valve, the Way Motor Works upgraded diverter valve, or the best yet the Forge diverter valve (not that stupid sandwich plate).

The hard starts definitely sound fuel pump related. Could be either the low pressure or the high pressure. I don't think there is an OBD code for a failing high or low pressure fuel pump. You really need the BMW diagnostic tool to see what the fuel rail demand is compared to the actual pressure in the rail to know what's going on.

I'd get a second opinion about this. It sounds like the dealer found your thermostat was having issues and immediately pointed the finger at it to make some service money. Their diagnosis just doesn't make sense with your hard start issues.

Regarding the battery, you can find replacements at big box auto parts stores. You technically have to tell the ECU there is a new battery but people that have swapped batteries without doing this step are doing just fine!

Where are you located?

 

Just had my thermostat replaced. When making the appointment, the service advisor asked if I noticed a loss of power; he said that the engine goes into a failsafe mode and power output drops when certain faults exist.

 

YES actually! I have a generic diagnostic OBDII code reader and I would go into this mode where i would have next to no power over 4k rpms. So I would erase the codes, and boom, full power again (except for the boost issue).

Dealership just called! They said that while taking off a tube thats connected to the turbo, they found that one was cracked. This tube is on the inlet side and after the MAF. This makes PERFECT sense! I told them to replace it to the tune of $127. I'm STOKED to pick it up now and see if it helped my boost issue.

Still not sure if my hard starts will be fixed but I'll update this tomorrow. Scheduled to pick up the car before midnight tonight.

BTW I live in Buena Vista, CO. 2hrs southwest of Denver.

 

See the above post regarding the boost issue - but I'm still thinking of getting rid of the BOV - thing is I don't really know how to do this. The BOV is installed on the noisemaker pipe. I'm pretty sure i don't want to just pull out the BOV and cork up that tube, right? But I'm not sure how it all goes back together???

If the cracked tube being repared doesn't fix my boost issue, I will definitely look into the diverter valve and the BOV for being the culprits.

Man my loaner car tho... 2011 MCS 6 speed is freaking awesome. Such smooth power and pulls in every gear. and quiet too. a very nice change of pace. I hope my newly repaired car will be like this. I've had this boost issue ever since i bought it a year and a half ago. Just dealt with it tho....

 

I would try and determine the make and model of the BOV you have then look for install instructions and just reverse them. Unless you making a lot more boost then the stock engine the OEM valve should be fine.

 

Just wanted to update for you guys.

The car is running GREAT now! I could not be happier. I went in there knowing for SURE that it was the fuel pump and was hesitant to accept their recommendation of the thermostat being the culprit. But after replacing that, and the cracked turbo pipe my car has never run better since the day i bought it. No boost cutting, very smooth power delivery, and great firm starts even after sitting overnight. I deff recommend Ralph Schomp in Denver for your MINI needs!

 

I'm having a similar issue with my car. Just replaced the thermostat but the turbo isn't making boost real well. Where is the turbo pipe located that you are having problems with?