M50 17mpg Help

[arthb7]

My car is running extremely rich. I been trying to find the problem but not sure yet. I have m50NV


02 sensor is new
AFM is new
Crankshaft sensor is new
Camshaft sensor is new
temperature sensor is new

I have the ebay headers y pipe connecting into one straight pipe to the muffler. Is it possible for the 02 sensor to be too far back and not reading the correct info?
Can anyone tell me how far the 02 sensor has to be from the engine to get the correct reading?

Thank you

[red911turbo]

Do you have any faults in DME? Smoke test for vacuum leaks?
The factory 02 sensor is right at the "Y" before the cats. It's pretty far back from the manifolds
To be honest, I get about 17-18 MPG in my m50tu...but I think that is gearing and my left foot.

Cheers,
Chris

[arthb7]

Well when I checked for codes I didn't get anything! I haven't checked the 02 sensor relay yet!

[shocwav3]

What do the plugs look like? Does it smell like its running rich? Depending on driving habits and your set up, that may not be to far off.

[E30NJ]

Purge valve? Common on M50,M52,M54...

[arthb7]

purge valve is properly connected to the e30 charcoal canister

[matthugie]

Do you have any faults in DME? Smoke test for vacuum leaks?
The factory 02 sensor is right at the "Y" before the cats. It's pretty far back from the manifolds
To be honest, I get about 17-18 MPG in my m50tu...but I think that is gearing and my left foot.

Cheers,
Chris

What are you doing with the clutch to get 17-18mpg?

OP, what tune are you running?

[sweet3]

The o2 sensor reading is not really affected by the distance from the exhaust ports. Its mostly the life of the sensor that gets affected. But to answer your question, 18 inches from the exhaust ports is about the stock range. If you are running forced induction, it should be a couple more inches. Probably about 25 inches or so should be safe.

What size injectors are you running? 17lb is stock i believe. Any more than that, and the ecu chip will need to be replaced with one that is tuned for those specific injectors.

[arthb7]

The car has stock injectors! Stock ecu! I'm not doing anything abnormal drive it daily 75% highways still get 18mpg! Yesterday I found a small air leak in the brake booster hose so I tightened that and it made it run smoother! Also found that my 02 sensor relay was a 5 pin when I only have 4 wires going it so I replaced it with a 4 pin relay and will see if anything gets better!

[THEhomelessONE]

Check the IAC hose under the intake, mine had popped off and started dumping extra fuel to make up for the lean condition. I'm running 19lb injectors, the ecu adjusted within 5 minutes, improved top end, get 21 mpg with 4.27 diff m50tu.

[arthb7]

Alright a little update! After getting the correct 02 relay it hasn't fixed anything but I did find a weird air leak. My car doesn't idle straight and my brakes have never really felt the same as before the swap. They feel really mushy and seem to engage a little late. So here is whats weird. If I pump my brake pedal the car start to run straight. If I stop pumping my brakes pedal then the crapy idle comes back. Is this a problem with the brake booster or just the master cylinder or both?

[mpowerful]

Booster diaphragm could be leaking.

[jalopi]

Stop driving WOT everywhere

[matthugie]

Tighten these then report back. There's also a connector below the reservoir in that pic that could have a leak as well.

[arthb7]

Tighten these then report back. There's also a connector below the reservoir in that pic that could have a leak as well.

I have tighten the hoses as much as I can! Nothing changed! I believe my brake booster is out and my 02 sensor might be out too! Will change them out hopefully this weekend and report back!