I noticed the car is running rich, with a heavy gas smell on start up. No check engine lights are on, so I am wondering if it's the DISA valve.
I swapped out the old DISA valve with an off-brand bought on Amazon. The build quality is similar to OEM, and the price almost identical to rebuild kits. I will report on the new DISA, as time goes on. Hopefully, my low MPGs are resolved.
I could tell an immediate improvement and idle. It also seemed like the 530i has more power, and isn't downshifting as much.
I figured my DISA was failing due to the rattling noise around 3500 rpm. I took removed the old DISA and there were no missing or broken parts, and the seal looked fine. I changed it out anyways.
Here are the things I have changed, that could change MPGs:
- OEM spark plugs
- Brand new valve cover gasket and seal
- Air filter
- VANOS seals
- Pre-Cat 02 sensors
- Intake and Exhaust VANOS sensors
- Pulleys, tensioners, and accessory belts
- Cleaned MAF, throttle body, and ICV
- Fuel Filter
- Oil changed every 5,000 miles
- Upper and lower intake boots
- All vacuum lines
The other items that need to be changed:
- CCV
- Post Cat sensors
- Throttle body gasket
- Coils
- MAF
- Injectors and o-rings
- Intake manifold gaskets
I can't think of anything else. Does the fuel pump affect MPG?
