2008 Mini Cooper S N14 rough idle, stall, no power, but easy start

Happy New Year Ladies and Germs,

2008 Cooper turbo with 176k miles. New engine and many associated parts and new trans installed at 145k miles. Has 176k miles now. 

Started with stalling in road followed by total lack of power to point could barely move under own power. Weird thing was no check engine light! Starts just fine but stumbles and dies after few minutes.

Giotto Autoenginuity (love hate relationship with that software) with BMW extension found nothing!. (Hate)

Bimmer Protool (software) found:

• 2B51 Airmass sensor signal
• 2B5F Air mass correction signal
• 2EF2 intake air temp sensor signal
• 289D Boost pressure sensor, electric
• 2A35 O2 sensor before catalytic conv: Dynamics
• 2BOB Throttle valve potentiometer
• 2B03 Throttle valve potentiometer 1 
• 2Bd3 Monitoring, power supply 2, Driver CY320
• E18F?
• E190?
• misfires on various cylinders

MAF is original from 2008.

I checked 4-wire (Bosch?) MAF 12v power voltage drop using 180 LOADPRO and it didnt drop but 0.1 volts. great.

I am afraid to use the Loadpro on the two 5v signal wires to check for voltage drop. Can I?

I did backprobe the MAF, KOEO, and it had 5 and 4.8 and 4.88 volts 

Intake Air Temp Sensor/Pressure sensor (post turbo): Did the same backprobing (3,3v, 5v power, 5,72v) and voltage drop (5volt power only) with and it checked out.

I am afraid to use the Loadpro on the two signal wires. Can I?

Also tested, high pressure fuel pump (OEM unit has 50 k miles on it) and low pressure fuel pump (changed with new motor) and both seem to check out.

Looked for vacuum leaks with brake cleaner....found none.

I dont have an oscilloscope so I cannot truly test signal from the MAF but the Bimmer Protool does show FLOW measurements varying with RPM. 

Maybe I have a BAD ground?!






 

Forgot to mention I installed a new Inerstate AGM battery in the last month.

Stalling started 4 days ago.

Never coded new battery to car until after the errors started but that didnt solve anything of course.

You need to replace the MAF with an original part from the dealer. The aftermarket ones do not work. These ECU's have also been known to fail.

You need to replace the MAF with an original part from the dealer. The aftermarket ones do not work. These ECU's have also been known to fail.

Its a Mini...everything fails. It leaks like a sieve. BMW would build the motor out of plastic if they could figure out how and get it to last just past warranty.

HALF BAKED cars.

I haven't proven the MAF is BAD. Why would I change it or the ECU?

The correction signal fault is why you would change it. (I know this doesn't explain much )

as for the o2 sensor fault, you probably need to replace that as well , they go out all the time.

once you have those two items replaced you can drive it and check to see what comes back.

( I am a BMW master tech of 12 years) I have seen this a few times. I KNOW THERE IS NO "PROOF" IN YOUR TESTING TO VERIFY THAT IT IS FAILED. But without using ista seriously will be your best route. worst case scenario you can always get a MAF from LKQ junkyard for probably close to $50.00 instead of the $400 and if it doesn't help you can always return to lkq. no harm no foul parts shotgun it just has to be an original part ONLY! Once you get those two done you can go from there and see what remains.

sorry to all the DANNER-ITES I know this is a parts shotgun and not any type of good testing or proper diagnostics. just based on experience and seeing this problem multiple times over the years.

also the ECU is the ground, so that why you would run into that issue. They short out all the time. you can get a used one pretty cheap and have someone clone it. new one is like $1800

Thanks for your thoughts BMWaddict !

Bosch OEM MAF is only $156 new from FCP Euro.  www.fcpeuro.com/Mini-parts/Cooper/?year=...words=BOS-0280218205  

I suspected a massive vacuum leak initially but brake cleaner test didnt show anything, then again it was running so rough I doubt it would have made much difference. It would just turn off in < 2 minutes

BTW: Its a replacement engine (new from dealer) with 30k miles and the valve cover started leaking within a few months. I ignored this.

I had a new gen valve cover from the previous motor with less than a 1000 miles. Put that on and checked all grounds and she ran like a champ...

Both O2 sensors were changed last 10k miles from ECS tuning which specializes in Mini BMW junk. I will keep an eye on those. Hopefully related to the vacuum leak.

I honestly think its the MAF however because its the only original part in the engine bay at this point.

Ive changed everything when I put in the new engine. Body has 176k miles on it..

I have ISTA...but its giving me problems. What do I look for on ISTA software?

BMWaddict I changed the MAF because it was still stumbling a little, I bought a BOSCH unit from FCP Euro. I erased all adaptations as well.

Before the car wouldn't even idle for more than 2 minutes.

With new valve cover would stumble occasionally. \

With new Bosch MAF, same thing....every few miles I get hesitation and stumble, but no CELs or codes yet.