E46 rough idle and knocking - poor air from fires

[Darlo]

I have a 2004 330i w/112k miles, Msport, 6-speed manual that I've had 4 months now. In excellent mechanical condition. I'm in Napa, CA where the smoke and ash from the Camp fire in Paradise is extremely dense. Took her for a 3 hour drive yesterday in very smokey conditions. Started her up today, and I suddenly have sporadic idling rpms, knocking(?) - feels and sounds like misfiring, as the entire car rocks. I checked the air intake and filter, but I'm no mechanic. I've been doing some research and found my symptoms most closely match either a vacuum leak, O2 sensor failure, spark plugs, or bad oil separator. Any input regarding how the E46 breathes it's air and what may be causing this problem would be appreciated!

[jclausen]

Check for faults and are there any warning lights on

[bmwdirtracer]

Yep. reading the codes in the computers will be step #1.

You can remove "O2 sensor failure" from the list, but add "coils".

[Breeze1]

And how was the filter when you checked it? The intake manifold (if that's what you're refering to) is upstream of the filter, so unless it has a leak it can't get damaged, as it's the filter's job to protect it.

If the car was flawless before that drive, I think your best bet for an "easy fix" is to change the filter or at least take it out and clean it with an air compressor

[Darlo]

Check for faults and are there any warning lights on

No SES or CEL lights at all

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And how was the filter when you checked it? The intake manifold (if that's what you're refering to) is upstream of the filter, so unless it has a leak it can't get damaged, as it's the filter's job to protect it.

If the car was flawless before that drive, I think your best bet for an "easy fix" is to change the filter or at least take it out and clean it with an air compressor

The air filter looked good, although the particulate matter in the air is so fine, it may not be visible. I will be replacing the air filter. I even tested the MAF by unplugging it while the car was running, no difference.

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Yep. reading the codes in the computers will be step #1.

You can remove "O2 sensor failure" from the list, but add "coils".

Will be getting a code reader

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I will be purchasing a new air filter and code reader. I'm leaning towards cois and/or spark plugs so far...

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Check for faults and are there any warning lights on

No SES or CEL lights at all

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Check for faults and are there any warning lights on

No SES or CEL lights at all

[bmwdirtracer]

Here's your best bet for an inexpensive scan tool. Do not buy a cheap OBD 2 code reader. OBD codes are nothing but government mandated emissions codes, and are not good diagnostic tools for your car.

http://www.foxwelltool.com/wholesale...d-version.html

You can buy this same device on Ebay, or, with a "Schwaben" label, at ECS Tuning.

[Darlo]

Here's your best bet for an inexpensive scan tool. Do not buy a cheap OBD 2 code reader. OBD codes are nothing but government mandated emissions codes, and are not good diagnostic tools for your car.

http://www.foxwelltool.com/wholesale...d-version.html

You can buy this same device on Ebay, or, with a "Schwaben" label, at ECS Tuning.

Awesome, thank you!

[Darlo]

Check for faults and are there any warning lights on

No SES or CEL lights at all

[Breeze1]

If unplugging the MAF made no difference, it's not a good sign (it should make the engine shake for a few secs) I don't see how smoke would impact coils or spark plugs.

In my opinion changing the filter and cleaning the MAF will most likely solve the issue. Especially the MAF, since the smoke has probably left a thin layer on its wires, which messes up the readings.

[Darlo]

Thank you...that's what my logic has been telling me...this is actually my first bimmer!
The air filter currently in there is made in France (didn't write down info before locking it back in there); I'm thinking of getting a K&N - any thoughts on that?

[shadowpuck]

the stock filter will do more than enough - quality replacements from Mahle or Mann are fine too.
definitely stay away from the filters which require being oiled or sprayed....

i'd also suggest being careful interpreting the results of unplugging the MAF. that will not rule out, or prove that a MAF is faulty.

just saw something else in your original post - just to avoid confusion; i don't think the e46 was offered as an m-sport. if i recall, it would be either a sport package, or performance package (ZHP). you can actually check this yourself by running your VIN against any one of the many BMW VIN Decoder sites running around.

and, here's the standard spiel i give anyone just walking into e46 bmw land:
unless you have records specifying the following, i'd also consider these items:
full cooling system overhaul (radiator, hoses, expansion tank, water pump, thermostat)
brake fluid flush


these cars love maintenance - most e46s at this point will need a few grand in "catch up" maintenance.
look into the BMW Car Club of America (BMW CCA) - membership is not expensive and parts discounts are available..


as for parts - i use OE/Genuine BMW parts almost exclusively. There are some good aftermarket choices out there at places like FCP Euro.


getbmwparts, and directbmwparts are bmw dealers selling bmw parts at competitive prices.


also, become familiar with realoem.com - it's an online parts catalog you can search by VIN (ignore the pricing).


if you plan on doing the work on this vehicle, a bentley service manual is a great purchase.


as to fluids - for coolant I always use and specify OE/Genuine BMW only, mixed 50/50 with distilled water. BMW brake fluid is affordable so I use it for my street BMWs. With club discounts, BMW oil is usually competitively priced so I use it as well; there are plenty of quality alternatives as long as it meets specs, etc.

[Breeze1]

I concur with shadowpuck about the oiled filters. They're said to actually be less efficient as far as filtration goes, and the oil layer is more likely to collect dirt. Generally speaking if you don't put a proper Cold air intake system with heat shield, pipes and all, there is no gain to be expected from it. Even with CAI's, don't expect more than a 5 to 10-12 hp at best... the sound they make depends on preferences...
If it's hp you're after, headers will be a far better bang for your buck.

[shadowpuck]

before adding HP - mod the driver.
on most modern cars, i'd say bigger bang for the buck is often in the DME/tuning as a first step after modding the driver....

[Breeze1]

Yes and no about the DME... Yes you can get 10 to 20 hp (maybe 30 for really large displacements?) on an NA engine with a tune up only, depending on displacement, but then if you upgrade parts you have to redo the tune up. It's usually advised to start by upgrading the physical parts before tuning the software to make the most of them.

Another route is to upgrade nothing as far as hp go and just upgrade the chassis and shed some weight...

Driver to me is a separate issue that is a constant as far as "tuning" goes.

[shadowpuck]

well, we've strayed way off topic here.
mod the driver first, worry about changing the car later. drivers learn better, and more quickly, in a lower powered stock car. mods come later, way later.

on a car like an e46, upgrading the software takes minutes and produces immediate results. changing headers on the same car does not take minutes, and especially in california might be rather problematic.

[bmwdirtracer]

Personally, I think the fire and smoke are coincidental to the problems. I'd recommend following normal diagnostic procedure, starting with reading the codes which are stored, having a look at the live data for the MAF and other items, to see what's out of line.

As for 20-30 hp from a tune, alone, on an E46, I disagree completely. BMW didn't give up 25 horsepower. Now, if you swap manifold, camshafts, and headers, AND do a tune for those items, yes, then you can gain that kind of horsepower.

SURE, someone trying to sell you a tune will tell you it's worth 25 hp....but then K&N will tell you their crap air filter will do that too.

B.S., by any other name, is still B.S.

[Darlo]

Well, I'm learning more than I thought I would...thank you!
Went with a Mann filter. Code reader I bought doesn't establish a link; exchanging it tomorrow, so no codes yet.
Replaced air filter, cleaned MAF. Still the same. The misfiring is at idle only it seems. Smooth at 2k rpm sitting still (have not road tested yet). I'm now "leaning" towards fuel mixture? What to look for that controls idle?

[bmwdirtracer]

Intake leaks. Get a smoke test of the intake system at a good BMW/Euro shop that has a smoke machine. And of course, a good BMW specific diagnostic scan tool.

[Darlo]

Thank you for the wealth of information...I went with a Mann filter. Cleaned the MAF. No improvement. I was hoping that unplugging the MAF would allow it idle smoothly, so that blows the idea it's a bad MAF, like you said.

I believe I have a ZHP. I have the "S767A" performance package, along with all the "M" logos on the wheels, steering wheel, shift knob. Thank you for the VIN decoder info! Cool stuff.

I purchased this car from a colleague of mine who was the original owner, taken to a local BMW specialist who's done all the maintenance and repair on it. They both are meticulous, the car has been extremely well maintained.

Again, excellent resources - thanks a bunch!

[shadowpuck]

yeah, unplugging the maf just puts the car in default mode where it runs off predetermined maps. it's a strategy that would allow the car to run if it lost the MAF signal.

nice - ZHP's are not super common.

[MarcoZandrini]

Find a reputable indie shop that specializes in bimmers at www.bimrs.org. Go to E46Fanatics and search for OBDFusion threads in which jfoj has commented. He’s the guru.

OBDFusion is an app for your smartphone or tablet. It requires either a WiFi adapter (iOS) or a Bluetooth adapter (android). The adapter plugs into the obd2 port under the dash.

[Darlo]

Just looked into the OBD Fusion App and adapters. I have an Android, so this will work! Any suggestion which model adapter is better? Is the cheap Veepeak just as good, or go with the proprietary OBD Fusion one(s)?