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Tom Neff
Tom Neff, Technician
Category: Car
Satisfied Customers: 295
Experience:  ASE certified, 30 + years of Automotive experience, previous SR71 aircraft mechanic, factory trained
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BMW: Mini Cooper..dealership..changing..hpfp, the plugs and some hoses

Customer Question

Hi there,
I have a 2007 Mini Cooper S that is having some issues. I took it to the BMW dealership and they just started changing parts. They replaced the HPFP, the plugs and some hoses. It is still running with a hesitation (very bad when the engine is cold) and the check engine light is on. The diagnostic showed that the mass air flow sensor and the engine temperature sensor are both "plausible". I don't want to just keep replacing things until it works! It's not under warrenty anymore...
Submitted: 6 years ago.
Category: Car
Expert:  Tom Neff replied 6 years ago.

Hi, my name is XXXXX XXXXX I can assist you with this.

My first question to the diagnostic tec. that is saying that the maf and the temp sensor are "plausible" would be to have him compare the data that the maf/temp sensor is producing and compare that to a known good maf/ temp sensor and see if there is a substantial difference. This process can be accomplished with and scan tool that can read engine data for the mini... If there is a substantial difference in the (gps) gallons per second reading replace it. if not then press on to the next possible cause... Ido not blame you for not wanting to keep throwing parts at it.. fix it right the first time!!!

 

 

Thanks and God bless.

 

Tom

Customer: replied 6 years ago.
Is there any way I can use an multimeter to check? Do you know where on the engine these sensors are? I was just under the hood and there are at least 2 air flow sensors plus another one (pressure maybe). There are also quite a few sensors on the engine itself. I'd like to check resistance through them so I replace the faulty one and not just all of them...

I should also mention that the radiator fan stays on for about 10 mins after the car is shut off, this happens no matter how long it has been running. All of these problems happened at the same time.
Expert:  Tom Neff replied 6 years ago.

Hi, sorry you can not use a multimeter to test these sensors, you have to use a data specific scan tool to check this stuff, that is where the get you to pay for the diagnostics. its not about the resistance its about the signal that they produce that is interpreted by the engines computer that determines what fuel ratios that need to be established due to engine temps. Your best bet is to use a scan tool.

Customer: replied 6 years ago.

Well, thanks for the input Tom, I'll let you know how it goes.
Expert:  Tom Neff replied 6 years ago.

No problem, hope it goes well for you.

 

 

 

Thanks and God bless.

 

Tom

 


Expert:  Tom Neff replied 6 years ago.

Just checking in, did you get it solved??

 

Tom

Customer: replied 6 years ago.
Hey Tom,

I priced out having the car plugged back in at BMW, but it was about the same cost as the thermostat I had to replace so I just went ahead with it and replaced the part myself. On a positive note, it's running much better! The check engine light is still on, and if I can't get it to turn off by myself, I'll bring it in and get them to reset it at the dealership... unless you know of any tricks?

Mike
Expert:  Tom Neff replied 6 years ago.

Hi Mike,

 

Try disconnecting the negative battery cable then step on the brake pedal for about ten seconds, reattach the cable. If you do not have any thing else wrong that should clear the processors memory and clear the check engine light for you.

 

Tom

Expert:  Tom Neff replied 6 years ago.

Did that solve the problem for you?

 

Tom