2000 c70 2.3 HP Turbo rough idle in drive

jmenard · Post by **jmenard** » 12 Aug 2020, 08:33

Hello

So I did not get a chance to test the VVT solenoid, but I did try starting the car with the MAF disconnected.
Like I said earlier it did noes not like that, the idle fluctuates from 700 to 13000ish rpm's and immediately
engages the fan and is on the verge of stalling out and only disengages once the negative terminal is
disconnected. not sure what this means in regards to this problem?
So I left the car overnight with the positive and negative terminals bridged over night and the car seams
slightly better but the idle is still definitely not right, I was able to drive on a quiet road last night and noticing
a growling during acceleration that sounds louder than usual. I also noticed that the vibration lessens when
the wheels are turned to the extreme Left or Right sometimes but not consistently.

I can't figure out what I'm missing.

Post by **bmdubya1198** » 12 Aug 2020, 09:03

Look into that VVT solenoid. Lack of a MAF signal will send the intake temp reading way up, causing the fan to come on. It will eventually shut off, it usually runs for 5 minutes or so. Your MAF sensor is likely just fine.

jmenard · Post by **jmenard** » 12 Aug 2020, 09:21

Thanks I will get to that possibly today or tomorrow it's supposed to rain for the next few days. This might sound crazy but is there a chance something related to the steering or suspension might be contributing to the problem? in still waiting on plugs and air filter.

Thank you for the help JR

Post by **misha** » 12 Aug 2020, 11:17

Maf sensor have nothing in common with cooling fan or ECT... as far as i know.

It measures intake air mass not intake air temperature.

Btw....when MAF is disconnected it should idle just fine ...without fluctuations...and certainly not that wide fluctuations from 700-1300rpm.

That is pointing that you have a problem somewhere else....like that dtc is pointing you out.

It will not idle or run properly untill you re-solve the source of that code.

viewtopic.php?f=1&t=58908

Post by **bmdubya1198** » 12 Aug 2020, 11:31

Perhaps I'm mixing it up with BMW MS45 MAF sensors, but I know my fan ran when my last MAF failed on my 2000 R.

Post by **misha** » 12 Aug 2020, 11:51

Maybe it's something with Denso management...but i really never heard that bad or unplugged MAF will force cooling fan to come on.

MAF is MAF it's reading air mass on whatever car make.
Unless it share the same ground with ECT and because of that...when you unplug Maf,ect loose it's ground and force the cooling fan to run in order to avoid overheating of the engine.

Post by **bmdubya1198** » 12 Aug 2020, 18:17

Well I bring it up because many MAF sensors have built-in intake temperature sensors. ME7 uses a separate IAT sensor. Either way, my car is ME7 and the failed MAF sensor kicked on the fan.
It's possible that it shared a ground with the ECT sensor, but I'm not sure.

Post by **abscate** » 13 Aug 2020, 07:23

With ME7 running MAF-less will indeed trigger high fan and fan overrun after turn off

I think the lack of Maf Temp signal is the most logical explanation

Post by **bmdubya1198** » 13 Aug 2020, 09:25

abscate wrote: 13 Aug 2020, 07:23 With ME7 running MAF-less will indeed trigger high fan and fan overrun after turn off

I think the lack of Maf Temp signal is the most logical explanation

Yup, that's what I was thinking. Makes the most sense to me.