Tune up

[Dan Dawson]

My 525it wagon is getting 15 mpg. Seems to be running rich by exhaust smell. Car has 168,000 miles on odometer. I am second owner and am guessing car has never had a prior tune up. My question is, Should I buy brand new oem coils. Will have to price check the coils. Advise needed. Dan

[ahlem]

I'd start with the plugs and see if that makes a difference before dropping the big bucks on coils. My son's e36 M3 was running lousy and improved dramatically with just plugs with the proper gap. You might check for vacuum leaks that would mess up your air/fuel readings.

[632 Regal]

Yep, plugs first.

When you take the old ones out stick them in cardboard to keep them in order and then read them. Could be very helpful down the road.

[shogun]

or visit the dealer and ask for a fault code readout, then you have the faults and then you repair the faulty parts instead of trial and error.

[Tiger]

Use regular plugs... not those +4 junks... single one is best.

It is most likely you have to change some sensors... and seals... as you most likely have vacuum leaks.

Mass Air Flow sensor should be cleaned with MAF cleaner.

[Dan Dawson]

Will change plugs since I did put four prong plugs in. Also will get mass air flow sensor cleaner. Where is the fuel filter? Dan

[Tiger]

fuel filter in rear right wheelwell... fuel filter rarely ever cause bad fuel mileage... 99$ chance it is not the problem.

Fuel pump however does affect fuel mileage and power.

[Rick L]

Use regular plugs... not those +4 junks... single one is best.


You mean the dual ground electrodes, Bosch FR7LDCR (BMW OE)? I believe superseded by plus (FR7LDCR+).

7740

[Rustam]

This seems like a very low number for m50 engine. Please check compression, leak down.

Please check vacuum at the brake booster. Foolproof procedure - remove the vacuum pipe from the manifold and try to suck in. The brake booster should not allow air into the engine.

A Bentley's repair manual should provide numbers for checking the coils, along with much other needed maintenance information, which would save money in diagnostics and repairs. Please consider investing in it first.