BMW E46 330i decat

[Sankekur]

I will then put in a performance filter, a unichip and remap to optimise for economy and dyno again to see the improvement. Glad to see you already noticed an improvement 2l is alot in my opinion.

Not to be the one to burst you bubble, but there is clearly something wrong with your car, 20+ l/100km is not normal, I have driven a 540i on the track and that will still less than this.
So before you start modifying perhaps you should first start diagnosing and fixing the problems with the car. Then you can start to modify, though personally I would steer you away from both things that you mentioned, the filter is pointless...as the e46 M3 uses the same filter as your 330i, so it is not a limiting factor on the engine output. The Uni-chip: They do good work but I am not a fan of their methods, but if want someone to cut your car's wiring harness then that is up to you.

Things that you can look at regarding you fuel consumption:
-do the decat, as this is good idea in any case
-the O2 sensors
-MAF
-injectors (the early design purple cap injectors used on the M54B30's have a tendency to leak)
-coil packs, the more compact coil pack used on the M54 don't seem to last very long and it would seem the 330i's tend to go through coils a little bit faster as well.
-vanos seals, at your mileage this is a good idea as it really isn't that expensive or that hard to do.
-check for vacuum leaks
-check the intake pipes between the MAF and the throttle and ICV, they have a tendency to crack with age.
-check the condition of the resonance flap in the intake resonance tube (often and incorrectly called a DISA flap)
-condition of you air filter (it is a good idea to change it every time you change the oil)
-when were plugs changed last

 

[GPGrobler]

Question about the standard air box, there is a hole in it which would continuously suck warm air from the engine bay, is this not bad for fuel consumption/performance?

 

[Sankekur]

There is probably something removed or changed on the intake as all the holes should allow for cold(er) air. The M54 intake draws air through the grilles through some ducting, and between the headlight and the radiator. (The BMWPerformance intake adds a third path in addition to a change in the filter element and the internal structure of the intake.)

 

[ChrisBrand]

Are you talking about the hole to prevent Hydro Lock?

 

[moranor@axis]

Im betting on O2 sensors

 

[GPGrobler]

Are you talking about the hole to prevent Hydro Lock?

Hi Chris, no, this is an elongated hole in the front of the airbox, which will be sucking hot air from the radiator core, as its opening faces the radiator. So I will close that up as I see no reason why the car should be getting hot air into the airbox.

Freerider mentioned making a 2" hole in the bottom of the air box for improved fuel consumption, has anyone tried this?

 

[moranor@axis]

Are you talking about the hole to prevent Hydro Lock?

Hi Chris, no, this is an elongated hole in the front of the airbox, which will be sucking hot air from the radiator core, as its opening faces the radiator. So I will close that up as I see no reason why the car should be getting hot air into the airbox.

Freerider mentioned making a 2" hole in the bottom of the air box for improved fuel consumption, has anyone tried this?

that hole should have a tube on it to draw air from in front of the radiator...

 

[GPGrobler]

All right, I guess if the nostrils and electric fan is missing, this can be missing too ...

 

[ChrisBrand]

Check Gizmo and someone else on the forum. Think its on a Cold Air Induction thread where they have a DIY on it. Will try and get it for you

---

Here you go.

http://www.bmwfanatics.co.za/showthread.php?tid=40779&page=2

 

[BMWfanforever]

Update on the heavy fuel consumption

A big thank you to everyone for the advice, definitely learned alot from the tips. :bravo: I decided to check the filters and MAF to check for obvious problems and I found the culprit. Whichever idiot who last worked on the engine forgot to tighten the clamp on the manifold side of the MAF so the whole time it has been sucking fresh unfiltered air into the system. After about 30kms over the weekend of town driving it's now showing just over 13l/100km whichseems bout right now.

Will still get the main cats done sometime and will update to see if further improvements are noticed.

Cheers guys. :ty:

 

[moranor@axis]

glad you sorted the problem

 

[Henry330i]

Good news glad it was something stupid and free to fix.

Sent from my GT-I9300 using Tapatalk

 

[Yuben]

Thats great news Bud. Now u can go ahead and mod what u wanted to do.

 

[GPGrobler]

:joy:

 

[Loom]

Where are you planning to do the decat?
Is a remap needed when removing the cats?

 

[BMWfanforever]

Hi guys,

It's been some time since the last posts so just thought I would give an update.
I spoke too soon thinking I had solved the fuel problem, since then I have taken this valuable info and changed the following:

Full service including fuel filter and plugs.
New battery (not part of the problem but it died)
Vanos seals incl gaskets etc. (huge thanks to Sean from Moranor)
Rear cats taken out and replaced with standard round boxes.
Had the codes read and only item was exhaust cam positioning sensor which I replaced.
Cleaned out the MAF.
Checked the intake boots and resonator flap (all good), no signs if vacuum leaks.
Then I did the manifold cats yesterday.

And after all that, the car is sitting at 19l/100km. :smashScreen:
Strange thing though, the exhaust guy told me there were no post cat 02 sensors, only the top 02 sensors in the manifold. Can this be the case on the M54b30 engine? I opened up the covers this morning to check, and if I am not mistaken, the connectors for the post sensors come to a dead end (unless that is something else)

If this is normal then fine, the only thing I can think of now is 02 sensors. Should I get them to check the oxygen /fuel levels on the machine.

I am not sure if throttle position has anything to do with it? Even on gentle acceleration the fuel consumption needle goes right to max consumption and stays there until i literally back right off the accelerator. Just throwing it out there.

Hopefully narrowing it down now, although thermostat I believe can also influence fuel.

Cheers guys.