Loss in mpg...

[BimmerWill]

Recently noticed that my mpg below below the tachometer seems to drop a lot more than what it used to when under acceleration. Before I was squeezing an easy 26 mpg out of it around town with little to no effort. Now it seems im having to fight for it. Im wondering if it has anything to do with the vanos seals I did. Perhaps didn't get something tightened up enough now its not working properly. Car was dropped on the rear rotor due to a failed jack about a couple weeks ago. I could just be being paranoid but it just seems like their is something holding it back. Rotor doesn't seem to have been warped or anything of that nature. Just curious if anyone has any thoughts.

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[danewilson77]

How old is your intake filter?

[BimmerWill]

Old...I haven't replaced it in close to 60k...

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[alexandre]

Albeit the car had an ECIS CAI when I bought it, the filter was filthy and I'd average 16 mpg in the city. I went back to stock airbox with new filter, cleaned MAF, ICV and DISA and I'm doing ~21-22 now. A filter is $14 so I'd definitely investigate into that. How old are O2 sensors ? I changed mine at the same time, and my MPG is much better now.

[BimmerWill]

Albeit the car an ECIS CAI when I bought it, the filter was filthy and I'd average 16 mpg in the city. I went back to stock airbox with new filter, cleaned MAF, ICV and DISA and I'm doing ~21-22 now. A filter is $14 so I'd definitely investigate into that. How old are O2 sensors ? I changed mine at the same time, and my MPG is much better now.

Yes I will look into an air filter. My 02 sensors are also throwing codes so I guess I should replace those as well..if I were to get a headed later on and trick the computer with dummy sensors would that negatively effect mpg as well?

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[danewilson77]

Damn.....that's a 15k mile item I think. I clean/change mine every time I change my oil.

[alexandre]

Yes I will look into an air filter. My 02 sensors are also throwing codes so I guess I should replace those as well..if I were to get a headed later on and trick the computer with dummy sensors would that negatively effect mpg as well?

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Since you have a prefacelift I think you have the older non-wideband sensors - i.e. they're like $45-50 each on Amazon/BMA/Pelican. Facelift 330 sensors are $100 a piece.

If you get headers you'll only need dummies for the post-cat sensors, and these usually only affect emissions, not your air-fuel ratio. They usually aren't replaced unless they throw codes.

[Ryans323i]

Mine are about $80 from ECS. But first things first, do the air filter. You'll be very surprised! Like Dane, I used to change mine every oil change, 7500miles. Now I have a cone filter (CAI) and I do 5,000 oil changes, and switch my filters (I bought 2) at every oil change or even when it looks dirty. You cant have combustion without air!

[BimmerWill]

Mine are about $80 from ECS. But first things first, do the air filter. You'll be very surprised! Like Dane, I used to change mine every oil change, 7500miles. Now I have a cone filter (CAI) and I do 5,000 oil changes, and switch my filters (I bought 2) at every oil change or even when it looks dirty. You cant have combustion without air!

I tried the oiled cone filter as well as the drop in k&n and they simply just caused my maf to send out false readings. Im hoping to get an oilless high flow at some point but for now ill try to pick up a paper filter. I believe the pr-cats are the ones throwing the codes so im guessing they need to be replaced as well regardless of getting headers or not. I had no idea the filters were supposed to be replaced that often :(

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[Mr Paul]

Recently noticed that my mpg below below the tachometer seems to drop a lot more than what it used to when under acceleration. Before I was squeezing an easy 26 mpg out of it around town with little to no effort. Now it seems im having to fight for it. Im wondering if it has anything to do with the vanos seals I did. Perhaps didn't get something tightened up enough now its not working properly. Car was dropped on the rear rotor due to a failed jack about a couple weeks ago. I could just be being paranoid but it just seems like their is something holding it back. Rotor doesn't seem to have been warped or anything of that nature. Just curious if anyone has any thoughts.

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With it getting close to winter gas companies switch to their winter blend of gasoline. You tend to lose a couple MPG's with this gas. This could be what you are experiencing.

[BimmerWill]

Had the codes read and came back with what I expected as far as the pre-cat sensors running lean bank 1 & 2 but there was also a P0491 which I hadn't seen before.

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[alexandre]

http://www.bimmerfest.com/forums/showthread.php?t=430048

[BimmerWill]

Okay looked at the vacuum lines all looked solid. Still haven't thrown an air filter in. I guess im hesitant to believe this is the root cause due to it being a rather sudden loss in fuel efficiency. Unless of course the pre-cats have completely failed but the cel for those has been on for some time..just feel as if I've missed something somewhere. I find myself hesitating to put my right foot down and I hate it :(

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[alexandre]

If you do a lot of city driving (idle at red lights, stop/go traffic, basically if you stay a lot in neutral) ICV is probably your culprit. It manages air intake at idle so when it gets dirty it screws up the gas/air ratio and your engine ends up consuming more gas. Maybe it got stuck open/closed/midway recently. How's idle at startup ?

[BimmerWill]

In the process of getting to my icv I removed the disa unit. It is in shambles. Pin fell out into the intake manifold as I pulled it out and the flap is no longer controlled by the spring it just flops around...could this be the cause of my troubles? I don't think I can afford a $200 part right now....but it looks like I can't simply put the car back together with the flapper now in disarray.
Someone looks to have designed a rebuild kit on bimmerfest. I have sent him a PM in hopes of procuring a quality solution to my failed DISA. Has anyone purchased a kit from Gary? Here is a link to his thread on the kit.

http://www.bimmerfest.com/forums/showthread.php?t=588505&page=1

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[BimmerWill]

In the process of getting to my icv I removed the disa unit. It is in shambles. Pin fell out into the intake manifold as I pulled it out and the flap is no longer controlled by the vacuum actuator it just flops around...could this be the cause of my troubles? I don't think I can afford a $200 part right now....but it looks like I can't simply put the car back together with the flapper now in disarray.
Someone looks to have designed a rebuild kit on bimmerfest. I have sent him a PM in hopes of procuring a quality solution to my failed DISA. Has anyone purchased a kit from Gary? Here is a link to his thread on the kit.

http://www.bimmerfest.com/forums/showthread.php?t=588505&page=1

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[alexandre]

German auto solutions sells a repair kit. $60 iirc. Don't start the engine with the pin in there...

[johnrando]

Just checked out the thread. Gary and German Auto Solutions are the same person. That DISA is mafia approved.

[BimmerWill]

Thanks guys...will be ordering the kit today.

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[johnrando]

They also have a "gold" DISA that's already pre-built... costs more but that's gotten good reviews too.

[BimmerWill]

They also have a "gold" DISA that's already pre-built... costs more but that's gotten good reviews too.

I dont mind rebuilding it myself. Plus I don't have that kind of cash laying around lol poor college student status.

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[WOLFN8TR]

I also have the GAS DISA, quality product. The car runs better with the DISA rebuilt. Man your lucky that pin didn't come loose and get sucked into your engine!

K&N filters are nice as far as being able to clean them. But I've read so many times the oil on the filter causes MAF issues. We installed one in our 4Runner last year, no MAF issues but the MPG went from 24 to 22! I've tried everything to get it back, no luck. Switched back to the OEM paper filter and 24 MPG is back. Anyone want to buy a slightly used K&N?

[alexandre]

Noticed the same thing... Avg mpg went up by 3 after switching from oiled ECIS to stock airbox. Throttle is more responsive too.

If you have the updated part #, is it still worth rebuilding the DISA or does it only apply to units with the old PN?

[WOLFN8TR]

I would say YES.

http://germanautosolutions.com/DISA_Valve_Repair_Kit.html

[BimmerWill]

I also have the GAS DISA, quality product. The car runs better with the DISA rebuilt. Man your lucky that pin didn't come loose and get sucked into your engine!

K&N filters are nice as far as being able to clean them. But I've read so many times the oil on the filter causes MAF issues. We installed one in our 4Runner last year, no MAF issues but the MPG went from 24 to 22! I've tried everything to get it back, no luck. Switched back to the OEM paper filter and 24 MPG is back. Anyone want to buy a slightly used K&N?

Yes I was freaking out when I saw it just laying there. Car stays apart til that rebuild kit gets in...sadly id just put the radiator in it and had only had it a day before it once again will sit for at least half a week.

I do believe that this is my culprit. Due to under normal operation it stays in the closed position up to heavy throttle which causes the vacuum opening it up allowing more air to travel through the manifold. With it failed the car is now operating as if it Is under WOT at all times throwing in extra fuel to compensate for the additional amount of air coming in.

Also discovered my upper intake boot has several minor gashes in it. Will be picking that up today. Another forty bucks in the car. I've spent nearly five hundred dollars in the last two weeks on various items including oil changes. Im hoping these last couple purchases for set her right. At least for a little while...
\rant

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[danewilson77]

That DISA is mafia approved.

Yes.....yes it is. You must have forgotten to mention you got a new intake filter as well huh?


http://www.youtube.com/watch?v=3RyiEJuX4ZQ&list=UUNt0wYLKnnwXPelgwDVrwYw&index=6&feature=plcp

[BimmerWill]

Yes.....yes it is. You must have forgotten to mention you got a new intake filter as well huh?


http://www.youtube.com/watch?v=3RyiEJuX4ZQ&list=UUNt0wYLKnnwXPelgwDVrwYw& index=6&feature=plcp

Air filter is also in the works. While im waiting I figured I might as well take off the icv and clean it. I've run into a problem removing it however. All connections and boots are off but im having trouble disconnecting the icv from what I would imagine is a rubber hose leading into the intake manifold. Im pulling but it's not budged. I can tell that is the only thing still holding it back but i don't want to pull too hard in fear of tearing something else. Any thoughts?

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[danewilson77]

It pops into it's spot via a rubber grommet.

Wiggle that shit!!!!!

Now!

[johnrando]

Too bad about the coin, but your car will rock from then on.

[BimmerWill]

It pops into it's spot via a rubber grommet.

Wiggle that shit!!!!!

Now!

Yes sir!

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[BimmerWill]

Too bad about the coin, but your car will rock from then on.

Yeah thats the hope anyway lol

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[BimmerWill]

Okay so got the ICV out and cleaned it thoroughly it now makes a lovely clacking noise when i move it back and forth. I went ahead and put it back on the car after using the air compressor to dry it out what i feel was sufficient. I do however want to make sure I shouldnt leave it off for a day or so to ensure that all the carb cleaner has evaporated from the unit. I don't want to try and start her up on tuesday and have it blow up from there being residual cleaner in the ICV. Thoughts? I could take it off again without too much trouble but if its not really that necessary I will leave it in.

[alexandre]

Carb cleaner is safe for that. I didn't even dry mine, I just reassembled everything and it started right up. It's made for that!

[BimmerWill]

Carb cleaner is safe for that. I didn't even dry mine, I just reassembled everything and it started right up. It's made for that!

Good deal. Thanks for the peace of mind! Rather be safe then sorry ;)

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[BimmerWill]

Ordered a new Mann filter from ECS last night. With my store credit was only $8.30 including shipping so couldn't pass that up :) she won't know what to do when I start her up Tuesday or Wednesday...now its just the waiting game. DISA is prepped and ready for the new parts.

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[WOLFN8TR]

Too bad about the coin, but your car will rock from then on.

BMW= Break My Wallet.

I wish Dane would quit selling his parts, it costs me money. I'm in Danes kids college fund for around $550 now. Ouch...
But now my ZHP is looking as cool as Danes so it's worth it.

[BimmerWill]

BMW= Break My Wallet.

I wish Dane would quit selling his parts, it costs me money. I'm in Danes kids college fund for around $550 now. Ouch...
But now my ZHP is looking as cool as Danes so it's worth it.

What did you pick up for that college fund? lol

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[BimmerWill]

Okay well got the car back together...still reading a loss in fuel efficiency. Im going to do the pen and paper method to be sure its not something electronic. Is there anything else that it could be to cause such a loss in mpg? I may be being paranoid but something just doesn't seem right. Runs just as strong as before but it just seems to drink gas instead of sipping it. Still thinking I've done something awry about the vanos seals.

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[alexandre]

How are you checking that tho ?

[BimmerWill]

How are you checking that tho ?

Just judging by how much the mpg gauge drops with just very slight presses to the gas that did not cause such drops before. I could be being paranoid like I said but I don't feel that I am.

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[danewilson77]

Drive it a while. Give us data from OBC and data from filling back up. I think you may be a little paranoid. Not discounting what you see/feel (as we are all pretty much in tune with our cars).....I just want some data.

[BimmerWill]

Drive it a while. Give us data from OBC and data from filling back up. I think you may be a little paranoid. Not discounting what you see/feel (as we are all pretty much in tune with our cars).....I just want some data.

Will do sir.

My only thoughts are that my pre-cats have completely failed and causing the car to run extremely rich. I've been putting off replacing them for a while now just because I didn't want to bite the bullet on how much they cost but it looks like if I don't replace them im going to run into more than just bad fuel economy...fouled plugs, clogged cat..

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[BimmerWill]

Wow is there anyway to get the sensors cheaper then 178 a pop??

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[BimmerWill]

Okay this looks much better.

http://www.fcpeuro.com/BMW-parts/330i/?utf8=%E2%9C%93&keywords=oxygen+sensor&e=180&m=20& year=2001

Thoughts?

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[shanneba]

The O2 sensors used on the M54 engine changed in 03/2003. Check your production date to make sure you get the correct sensors:

http://www.realoem.com/bmw/showparts.do?model=BD53&mospid=47713&btnr=11_2181&hg=11&fg=50


No. Description Supplement Qty From Up To Part Number
01 REGULATING LAMBDA PROBE L=320MM 2 03/2003 11781742050

01 REGULATING LAMBDA PROBE L=1010MM 1 03/2003 11787523434

http://www.realoem.com/bmw/showparts.do?model=BD53&mospid=47713&btnr=11_3555&hg=11&fg=50

You will loose 2-5% in gas mileage with winter blend gasoline.
Colder temps will also contribute to decreased gas mileage as the engine, engine, transmission, and diff fluids are thicker at colder temp and take longer to warm up.
Just for future reference, replacing your air filter in a modern computer controlled engine doesn't improve gas mileage but does improve performance:

http://www.fueleconomy.gov/feg/pdfs/Air_Filter_Effects_02_26_2009.pdf

Results show that clogging the air filter has no significant effect on the fuel economy of the newer vehicles (all fuel injected with closed-loop control and one equipped with MDS). The engine control systems were able to maintain the desired AFR regardless of intake restrictions, and therefore fuel consumption was not increased. The carbureted engine did show a decrease in fuel economy with increasing restriction. However, the level of restriction required to cause a substantial (10–15%) decrease in fuel economy (such as that cited in the literature3,4) was so severe that the vehicle was almost undrivable. Acceleration performance on all vehicles was improved with a clean air filter.

[BimmerWill]

Im getting at least a 10-15% drop in fuel economy right now. Ses light came on this morning on my way to class. Im going to have it checked im just about positive it will be my o2 sensors.

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[BimmerWill]

Advance has the bosch sensors for 80 a piece..

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[alexandre]

Amazon usually has the cheapest prices on those. If you give me last 7 characters of your VIN i'll let you know what you need. Since you're prefacelift you should have the cheaper ones (~$45-50 a piece).

Edit: BTW, I went from 13 mpg city to 19 with new O2's and the maintenance I suggested (ICV, etc). It's very possible that they're your culprit, and mine didn't even throw codes.

[BimmerWill]

Amazon usually has the cheapest prices on those. If you give me last 7 characters of your VIN i'll let you know what you need. Since you're prefacelift you should have the cheaper ones (~$45-50 a piece).

Edit: BTW, I went from 13 mpg city to 19 with new O2's and the maintenance I suggested (ICV, etc). It's very possible that they're your culprit, and mine didn't even throw codes.

Ill check last 7 when I get out of class today. Are their different part numbers for the front 3 cylinders and the back three or are they both the same part?

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[BimmerWill]

FT01170

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[BimmerWill]

Bosch 13477

Im thinking that's the part number I need but im not sure.

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[BimmerWill]

Had codes read tonight came back with p0491 and p0492 secondary air system. I took a look at the vacuum lines earlier last week but I guess I didn't do a very good job. No codes for the o2 sensors though...guess its back to the drawing board.

Would this system being bad cause me to have poor gas mileage?

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[Hornung418]

Yes. Leaky vac lines are notorious for lean codes. Check for cracks at the mating points and check that your SAP valve (thing that mounts to the head) isn't rusted open. Happens when water gets in there.

[BimmerWill]

Yes. Leaky vac lines are notorious for lean codes. Check for cracks at the mating points and check that your SAP valve (thing that mounts to the head) isn't rusted open. Happens when water gets in there.

Would this system failing namely vacuum lines cause the car to have a considerable loss in fuel mileage?

Didn't have any lean codes. Just the secondary air system ones.

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[alexandre]

Bosch 13477

Im thinking that's the part number I need but im not sure.

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Yup that's it. I actually ordered those by mistake when I was shopping... For prefacelift they're $48 ea. at Amazon (http://www.amazon.com/Bosch-13477-Oxygen-Sensor-Fitment/dp/B000GZEK00/ref=sr_1_1?ie=UTF8&qid=1351793962&sr=8-1&keywords=13477). Had I known I would've shipped them your way instead of dealing with a return to Amazon USA from Canada!

For the SAP I don't know... Haven't dealt with it yet.

[BimmerWill]

Checked my vac its blowing strong. Just need to check the valve and then if that's good start scouring for the various vacuum lines on the system.

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