The Random E46/ZHP Question Thread

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Originally Posted by NYRhockey

What are the common causes of poor gas mileage? Today i put in 15 gallons after 302 miles and been getting 20-21 consistently, probably since i've had the car. Seem to remember getting mid 20s (24-26) in my previous zhp?

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I'm in the same boat. Think my DISA is shot.

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Originally Posted by NYRhockey

What are the common causes of poor gas mileage? Today i put in 15 gallons after 302 miles and been getting 20-21 consistently, probably since i've had the car. Seem to remember getting mid 20s (24-26) in my previous zhp?

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Really depends on a number of things. Do you have any codes?

Things that can cause poor mileage include:
* Intake leaks
* Clogged fuel filter
* O2 sensors nearing or surpassing 100k
* Bad MAF
* Spark plugs / ignition coils (unlikely though)
* Clogged catalytic converter (this one is my issue)

And the most important one:
Non-fuel efficient driving (driving style)

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Originally Posted by az3579

Really depends on a number of things. Do you have any codes?

Things that can cause poor mileage include:
* Intake leaks
* Clogged fuel filter
* O2 sensors nearing or surpassing 100k
* Bad MAF
* Spark plugs / ignition coils (unlikely though)
* Clogged catalytic converter (this one is my issue)

And the most important one:
Non-fuel efficient driving (driving style)

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Interesting! I know for sure my o2 sensors are originals, at 137k. How do they cause bad mileage? Providing an incorrect Fuel/Air mixture?

And how do you determine that your Cat is clogged?

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The winter fuel blend also result in fewer MPGs vs. summer blend. Nice that regular is $1.88 & premium $2.18 currently!

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Originally Posted by 3LiterStraightSix

Interesting! I know for sure my o2 sensors are originals, at 137k. How do they cause bad mileage? Providing an incorrect Fuel/Air mixture?

And how do you determine that your Cat is clogged?

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Yes, the O2 sensors are very sensitive pieces of equipment. They help with adjusting for air/fuel mixture.

My car has clogged cats, with a serious loss of power/torque and a huge hit on fuel economy. Where I used to be able to easily hit 30-31 mpg highway, before O2 sensor replacement I struggled to hit 24, and a Prius can out-accelerate my car. Acceleration also feels funky; sometimes it's a little choppy. Here is a video I took on accelerating on to an on-ramp. 3rd gear, 45 mph to almost 75 mph took that amount of time.

https://youtu.be/MH4jsI4EOFo

Replacing my O2 sensors allows me to at least maintain 25-26 mpg, even with the clogged cat.

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Originally Posted by John in VA

The winter fuel blend also result in fewer MPGs vs. summer blend. Nice that regular is $1.88 & premium $2.18 currently!

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It doesn't make that much of a difference with a well running vehicle, in my experience.

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Originally Posted by az3579

Really depends on a number of things. Do you have any codes?

Things that can cause poor mileage include:
* Intake leaks
* Clogged fuel filter
* O2 sensors nearing or surpassing 100k
* Bad MAF
* Spark plugs / ignition coils (unlikely though)
* Clogged catalytic converter (this one is my issue)

And the most important one:
Non-fuel efficient driving (driving style)

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No lights on dashboard so no codes that I’m aware of. Car drives fine and the same way since i got it so just confused as to what it could be. Turns out there are various reasons for it. I’m pretty sure previous owner did spark plugs but o2 sensors I believe are original.


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Which O2 sensors should be replaced? precat or post cat? Is it a pretty easy job?

Pre-cat. Yep it’s easy. They are right on top of the manifold

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Originally Posted by John in VA

The winter fuel blend also result in fewer MPGs vs. summer blend. Nice that regular is $1.88 & premium $2.18 currently!

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Aw man I’m paying close 4 bucks a gallon for 91 octane. And that’s CA 91 which is diluted with ethanol -_-.


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Originally Posted by NYRhockey

No lights on dashboard so no codes that I’m aware of. Car drives fine and the same way since i got it so just confused as to what it could be. Turns out there are various reasons for it. I’m pretty sure previous owner did spark plugs but o2 sensors I believe are original.


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Well, you're local - we can do a drive cycle with me driving and I'll let you know what I think. [emoji6]

We have to discuss your lighting situation, by the way.

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Originally Posted by ComradeNick

Aw man I’m paying close 4 bucks a gallon for 91 octane. And that’s CA 91 which is diluted with ethanol -_-.


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$4.01 in NorCal

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Originally Posted by Sockethead

Pre-cat. Yep it’s easy. They are right on top of the manifold

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Just watched a 50skid video. Looks easy. What is the part number? On FCP euro I am seeing 3 different kinds of o2 sensor. I am guessing it's the one labeled "upstream"... damn these things are expensive!
Also, while on the topic, how often should post-cat sensors be replaced?

UPDATE: found which o2 sensors I need. They are way more expensive for newer e46s. Over $250 for a pair :facepalm

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Originally Posted by stephenkirsh

$4.01 in NorCal

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Where are you? I just filled up in NorCal and drove down to SoCal for uni. I paid 3.65 for 91 a few mins north of SF.

Was really shocked to see I could really only get 24mpg on my journey. It was cold, it was raining hard, and I had 300lbs of stuff in the car, but I don’t feel that’s a good reason to lose 4-5MPG. Definitely will ponder on the pre car sensors

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Originally Posted by papa_g

Just watched a 50skid video. Looks easy. What is the part number? On FCP euro I am seeing 3 different kinds of o2 sensor. I am guessing it's the one labeled "upstream"... damn these things are expensive!
Also, while on the topic, how often should post-cat sensors be replaced?

UPDATE: found which o2 sensors I need. They are way more expensive for newer e46s. Over $250 for a pair :facepalm

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Don't buy the OE ones; they're a total waste of money. Get the Bosch ones, PN 17215, Qty 2. Same part number for both banks. Way cheaper, same part.

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Originally Posted by az3579

Don't buy the OE ones; they're a total waste of money. Get the Bosch ones, PN 17215, Qty 2. Same part number for both banks. Way cheaper, same part.

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This right here is the ticket. And O2 sensors are definitely something that you don't want to go off-brand on. You'll see plenty of Chinese options in the $50 range when you search for the Bosch part number, but you'll just end up with the same problems from a slow reacting sensor.

Bosch 17215 Oxygen Sensor, Original Equipment (BMW) https://www.amazon.com/dp/B000CF3WOY..._AHHmCb2NKM680

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Originally Posted by YoitsTmac

Where are you? I just filled up in NorCal and drove down to SoCal for uni. I paid 3.65 for 91 a few mins north of SF.

Was really shocked to see I could really only get 24mpg on my journey. It was cold, it was raining hard, and I had 300lbs of stuff in the car, but I don’t feel that’s a good reason to lose 4-5MPG. Definitely will ponder on the pre car sensors

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Petaluma. It’s always slightly more expensive than SF for some reason.

Would bad O2 sensors throw a code?

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Originally Posted by johnrando

Would bad O2 sensors throw a code?

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Yes. Not a specific one, though.

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Originally Posted by johnrando

Would bad O2 sensors throw a code?

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If they are reading out of spec, then yes. Sometimes they can just be really worn but not bad enough to throw a code. In these instances you'll lose out on fuel economy, but the readings would still be within spec to not trigger a code.

My cat(s) are definitely bad. I wouldn't say clogged, but this shouldn't be happening. The Bank 1, Sensor 2 voltage should be relatively stable like the Bank 2 Sensor 2 voltage. I have headers coming soon :)

https://farm5.staticflickr.com/4914/...24848b62_z.jpg

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Originally Posted by stephenkirsh

Petaluma. It’s always slightly more expensive than SF for some reason.

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I’ll be damned. I’m 10 mins from San Rafael. We got a Z4 race car in Santa Rosa and a 135 that basically needs $1 in maintenance for every mile drive. Cool to know there’s other members so close! I wonders if I’ve ran into you at a cars and coffee.

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Originally Posted by ZHPizza

This right here is the ticket. And O2 sensors are definitely something that you don't want to go off-brand on. You'll see plenty of Chinese options in the $50 range when you search for the Bosch part number, but you'll just end up with the same problems from a slow reacting sensor.

Bosch 17215 Oxygen Sensor, Original Equipment (BMW) https://www.amazon.com/dp/B000CF3WOY..._AHHmCb2NKM680

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This is for newer e46's right? Pretty sure my 01 has a different part number and is only 60 bucks

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Originally Posted by 3LiterStraightSix

This is for newer e46's right? Pretty sure my 01 has a different part number and is only 60 bucks

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Yep. I saw that the guy asking also had an '05 so I confirmed BP's part number with what I had on my purchase sheet.

Yeah. I also saw the older e46s have a way cheaper o2 sensor haha... why is that anyway?
The Bosch sensors are $127 each at FCP euro. At least then I can replace for free.

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Originally Posted by YoitsTmac

I’ll be damned. I’m 10 mins from San Rafael. We got a Z4 race car in Santa Rosa and a 135 that basically needs $1 in maintenance for every mile drive. Cool to know there’s other members so close! I wonders if I’ve ran into you at a cars and coffee.

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Why $1 per mile?

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Originally Posted by stephenkirsh

Why $1 per mile?

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Because it’s done 3,000 miles since it’s purchase and cost $3,000 between warranty claims and maintenance. Granted it has been tracked but still

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Originally Posted by az3579

Well, you're local - we can do a drive cycle with me driving and I'll let you know what I think. [emoji6]

We have to discuss your lighting situation, by the way.

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ha, true story. Might need you to take it for a spin one of these days, though now with the worst part of winter coming and you having the touring to also take care of, might need to wait til spring to figure out the lighting situation.

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Originally Posted by YoitsTmac

Because it’s done 3,000 miles since it’s purchase and cost $3,000 between warranty claims and maintenance. Granted it has been tracked but still

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Oh gotcha lol

What groups/classes for the z4?

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Originally Posted by stephenkirsh

Oh gotcha lol

What groups/classes for the z4?

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Sorry, guess I should have been clear. It’s the track car for us/him. Every bushing is poly, suspension and drivetrain fully rebuilt, and is officially too stiff for his girlfriend to want to ride in. Its new to the family and also one of the only E85 Z4’s with an MS43 for easy tuning. If wallet permits it’ll get an N54 this summer. It’s such a blast.

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Originally Posted by YoitsTmac

Sorry, guess I should have been clear. It’s the track car for us/him. Every bushing is poly, suspension and drivetrain fully rebuilt, and is officially too stiff for his girlfriend to want to ride in. Its new to the family and also one of the only E85 Z4’s with an MS43 for easy tuning. If wallet permits it’ll get an N54 this summer. It’s such a blast.

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You lost me with the coding stuff. I think ms43 is for m54s?

MS45.1 replaced the MS43 DME. MS45 can do more from an engine management viewpoint but because of that, it’s more complicated to tune.

And apparently the MS45.1 has more security built into it, making it very difficult to break into.

Back to the O2 sensor question: Will be replacing pre-cat sensors. Should I also replace post-cat sensors? What is the service interval on the post-cats? I am at 95k miles.

Just do the pre-cat. The other ones do nothing other than monitoring the cats...

Hey guys, I found some plugs in a box that my brother had and was wondering if anybody has any thoughts on these plugs. I took one of the old ones out and they are a bit different. They do come up as a fit when i searched.

Attachment 34636

Attachment 34637

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Originally Posted by zak

Hey guys, I found some plugs in a box that my brother had and was wondering if anybody has any thoughts on these plugs. I took one of the old ones out and they are a bit different. They do come up as a fit when i searched.

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They should be fine. Bosch & NGK were both used.

Thanks

Anyone have the PN for the plastic cover that’s in the engine bay (top) that I believe covers the wiper motor?

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Originally Posted by BADCLOWN

Anyone have the PN for the plastic cover that’s in the engine bay (top) that I believe covers the wiper motor?

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The windshield cowl?

51718208483

https://c1552172.ssl.cf0.rackcdn.com/120138_x800.jpg

Negative, the wider/slightly shorter piece above where a strut bar would go but below the cowl piece you posted