Thoughts Before I Buy

[TomMan7531]

Hi All,

Just hopefully about to pick up a 2000 740 with the check engine light on. I wont be picking it up without an OBD 2 diagnostics on the day.

https://www.youtube.com/watch?v=IymL3nD4TUE&t=14s
The owner claims he doesn't know the issue but did record this video and writes
'At 1:30 it goes to it's normal idle when it's warmed up slightly. At 2:00 I rev it to show how the revs drop slightly if it's revved gently (as it only does it when it's revved really gently).'

Having looked around people suggest a number of sensors, but has anyone else had a similar issue with a solution and rough cost?

Besides that I am looking at buying advice pages but any tips for the day would be amazing and cant wait to hopefully pick one up.

Thanks,
Tom.

[KinkedChrome]

My bet is that the plastic tube from the secondary air pump is broke and leaking. Does it sound like there is an exhaust leak at idle also? Then it goes away after 2 min when the idle returns to normal.

[TomMan7531]

My bet is that the plastic tube from the secondary air pump is broke and leaking. Does it sound like there is an exhaust leak at idle also? Then it goes away after 2 min when the idle returns to normal.

Not sure yet, seeing it Sunday and must say it's suspicious video had no audio but he's aderment the engine sounds normal.

I will listen out on the day so thanks for that, I assume that would throw up the check engine light?

[bluptgm3]

You could buy a Peale Tool and read the codes in BMW speak.

https://www.peakeresearch.com/appguide.htm


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[acspecialists]

I would get a laptop loaded with INPA and a 20pin cable. The idle should be much lower and the engine revving could be many things. A simple test would be to unplug the MAF and run the car. If the symptoms change that's $400 for a MAF. Next would be a vacuum leak from the manifold gaskets. Not expensive but fairly involved DYI.

Good luck