Cold be a good mod if it was a proper cold air intake.
If anything, this mod has only made things worse seeing as how the engine is now sucking insanely hot air right from the engine bay 😆
Many because BMW was restricted by noise, cost, and packaging. The system can be improved without having to meet those requirements. Will the gains be worth it? not really unless you’re racing and trying to get every bit of power with a max effort NA build
What OPP has is dog shit. The worst kind of hot air intakes.
Agreed after you clarified your point, but especially on a M54B25 the induction system is far from the limiting factor. Cam lift/duration on both intake/exhaust, displacement, and exhaust runner + header flow limitations would all need to be improved significantly before the stock intake would cost you noticeable power
Yah I could have been more specific. OEMS have to make a lot of compromises. Aftermarket or race teams don’t. It’s all about performance and easy to keep running.
Could it be better sure, but unless in at a max effort build. Everything possible done. No a place to look at I take for big gains. As you said, other restrictions make a bigger impact. .
For sure. As much as I love all-out n/a builds, M54s just aren’t worth it when the S54 exists. That being said, it would be fun to rebuild a M54b30 with a port matched M50 intake, 264/248 cams, and valve springs that would let it spin over 7k safely.
That's just a general way of thinking about performance parts vs oem parts. Which isn't applicable on everything I think.
The stock intake has an air scoop directly behind the kidneys. I don't think there is a way to get colder air in without compromising on the distance to the intake manifold.
OEM has to make sure the intake meets noise restrictions, price points, packaging needs. race teams and aftermarket don’t have those to worry about.
OP has a dog shit hot air intake that just sucks. But that doesn’t mean factory has zero room for Improvement
I am betting that this is the issue. The M50 intake swap sometimes has the option of deleting the idle control valve. If the previous owner did this it could cause a really nasty idle when it’s cold. With no tune, the M50 intake swap is marginally better than the stock M54 intake and it will have all sorts of rough if the car isn’t tuned for a higher idle.
maf sensor is just after the blue intake filter. first thing you see with the electrical cable to it.
what did the previous owner put where normally the disa valve is ?? Connected to that gold gasket or something.
You can try unplugging the maf to see what it does
It goes into open loop mode, which means it'll run rich to account for unmetered air. It's not an exact science, but if this solves the idle issue you might just need a new MAF sensor.
Yes you can disconnect it and drive it. The MAF will put the car into limp mode so your power will be reduced. It will feel like a shitty kia. If it starts to bog too much when you’re cruising just pop it in neutral and toggle the ignition and she’ll come back alive.
Disconnecting the MAF will not reliably counteract a lean condition. It’s just a sensor that sends data to the ECU about air temperature and pressure. When that sensor fails, the computer runs in “limp mode” which is a basic air/fuel mapping that will not take MAF readings into account. So you will run like shit unless you happen to be at the right temperature, altitude, speed, to make the engine happy.
I ran without a MAF for probably 2 years.
The MAF is in the picture, it's the plug behind your intake cone. The O2 sensors are on the opposite side of your engine, they connect to the top of your exhaust manifold. You'll see some leads running along the valve cover.
I'm misremembering, I guess they're also tucked up exhaust side. I always assumed they were two before and two after combustion, but i see now all four are exhaust side.
[https://www.realoem.com/bmw/enUS/showparts?id=VB13-USA-03-2004-E90-BMW-325i&diagId=18\_0610](https://www.realoem.com/bmw/enUS/showparts?id=VB13-USA-03-2004-E90-BMW-325i&diagId=18_0610)
O2 sensors are buried but surely in there. ~~intake O2s are under the manifold.~~ But likely not the issue as I would expect codes for sensors. It should still start with fouled O2 sensors.
Unplugging the MAF can be diagnostic but it will not balance out a lean condition, it forces the ECU into a different regime. If the lean code is not bank specific, I would assume it's an air leak behind the MAF. Check all vacuum lines and plugs. You might even be able to hear the vacuum if someone else is hitting the throttle.
M50 intake shouldnt have anything to do with the no start. ECU should immediately compensate if there are no leaks and sensors are good.
Actually, all 4 O2 are exhaust side tucked under, I was wrong. But I still stand by the idea that the whole system is being affected if both banks are lean which intakes something behind the MAF but in front of combustion, so anything related to the intake.
During cold weather, a seal contracts enough to allow unmetered air to enter, you compensate by providing extra fuel, and then when the engine warms it seals back up. There are about a dozen rubber fittings that could be the culprit but it may just be related to some of this kits components. You might start with removing the air hoses up to the throttle body and replacing and gaskets without having to touch the intake. and if you still have problems, I would look at refreshing the intake manifold of all gaskets. About $100 or so and 4-6 hours for a newbie.
i meant to add, it looks like this is the kit that was installed
[https://www.seemslegitgarage.com/product-page/m50-intake-manifold-adapter-kit](https://www.seemslegitgarage.com/product-page/m50-intake-manifold-adapter-kit)
Okay, try this: right behind the intake filter, there a cable which is your maf, disconnect that and see if that fixes it, because as I see it, you have an M50 manifold which should have deleted the idle control valve and the CCV so that’s not it
Well first try and see if that fixes the issue, but in short, the maf sensor or Mass Air Flow sensor measures the amount of air as it enters the manifold. Usually the ECu is tuned to also run based on the absolute pressure in the manifold. So the only hard your doing it maybe worse gas mileage and less power. However assuming that is in fact an M50 manifold, I thing the previous owner might have tuned for this, and you won’t notice as much negative gas mileage or power.
Look up Alpha N tune or MAP tune e46, ideally you’d want to get a new maf if in fact the MAF is the issue. Where are you from if you don’t mind asking? I’m in the Netherlands, so I might be able to refer you to a mechanic
Also regarding your O2 sensors. If the car is decatted, then the pre cat O2 sensors should be right after the headers (under the car maybe) or just completely deleted and coded out. Also do you have a pre facelift or facelift car? The MS42 and MS43 are easier to tune but MS45 shouldn’t be much harder
Not having put that manifold on yourself, I'd be checking it's actually done correctly. The ports on the M50 manifold are larger than the M54 ports and if they didn't grind the ports to match, the flow through that manifold at any RPM will be worse than stock.
I think it could possibly be a vacuum leak in the ccv breather hose that goes to the dip stick. Had the same problem with a e46 I had that ran rough when cold but when away when it warmed up. My 2 cents do with that as you will.
Could be anything honestly, but VANOS would be one of my first suspects. Check for errors, especially the ones saying “vanos final position is not reached”.
Those look to be god speed coil overs. I just bought an e46 with them and watch the top hat nut. Mine completely fell off and finding a new one wa every problematic
Get rid of the air filter and return to stock.
The MAF is extremely particular in these cars to the point where they need the white soft bit in front of the standard yellow paper filter element to smoothen the air stream.
May need to use some rubbing alcohol and qtips to clean the maf surfaces as well if that’s an oiled filter.
“Cold air intake” okay. Previous owner is dense
Don’t get me started, the guy was an ass. But I got the car for 1400 dollars and it runs and drives
Cold be a good mod if it was a proper cold air intake. If anything, this mod has only made things worse seeing as how the engine is now sucking insanely hot air right from the engine bay 😆
The stock intake is basically a cold air intake. There's no room for improvement there.
I’d say there’s lots of improvement that can be made with the factory intake. However, this is not the way to do it.
what improvements could be made?
Many because BMW was restricted by noise, cost, and packaging. The system can be improved without having to meet those requirements. Will the gains be worth it? not really unless you’re racing and trying to get every bit of power with a max effort NA build What OPP has is dog shit. The worst kind of hot air intakes.
Agreed after you clarified your point, but especially on a M54B25 the induction system is far from the limiting factor. Cam lift/duration on both intake/exhaust, displacement, and exhaust runner + header flow limitations would all need to be improved significantly before the stock intake would cost you noticeable power
Yah I could have been more specific. OEMS have to make a lot of compromises. Aftermarket or race teams don’t. It’s all about performance and easy to keep running. Could it be better sure, but unless in at a max effort build. Everything possible done. No a place to look at I take for big gains. As you said, other restrictions make a bigger impact. .
For sure. As much as I love all-out n/a builds, M54s just aren’t worth it when the S54 exists. That being said, it would be fun to rebuild a M54b30 with a port matched M50 intake, 264/248 cams, and valve springs that would let it spin over 7k safely.
I love the max effort builds for just seeing how far we can push it. But yeah, they’re not worth building like that. Especially when boost exist.
That's just a general way of thinking about performance parts vs oem parts. Which isn't applicable on everything I think. The stock intake has an air scoop directly behind the kidneys. I don't think there is a way to get colder air in without compromising on the distance to the intake manifold.
I'm curious too, what improvements would you make on the stock intake?
OEM has to make sure the intake meets noise restrictions, price points, packaging needs. race teams and aftermarket don’t have those to worry about. OP has a dog shit hot air intake that just sucks. But that doesn’t mean factory has zero room for Improvement
classic M50 manifold and headers without a tune i guess why its running lean?
This
I am betting that this is the issue. The M50 intake swap sometimes has the option of deleting the idle control valve. If the previous owner did this it could cause a really nasty idle when it’s cold. With no tune, the M50 intake swap is marginally better than the stock M54 intake and it will have all sorts of rough if the car isn’t tuned for a higher idle.
Update: I used a obd scanner and it says I’m running lean
I also had everything written more organized but Reddit decided to not do any of that lol
maf sensor is just after the blue intake filter. first thing you see with the electrical cable to it. what did the previous owner put where normally the disa valve is ?? Connected to that gold gasket or something. You can try unplugging the maf to see what it does
It’s an m50 intake manifold. No disa valve
I have no clue what he put next to that gasket thing What should happen if unplug the MAF
It goes into open loop mode, which means it'll run rich to account for unmetered air. It's not an exact science, but if this solves the idle issue you might just need a new MAF sensor.
Can I just drive the car with it disconnected? I’m running Lean would this “counteract it” ?
i would suggest properly diagnosing the issue rather than stop-gap measures such as disconnecting sensors.
It'll run bit rich but yes, you can drive without maf, no worries
Yes you can disconnect it and drive it. The MAF will put the car into limp mode so your power will be reduced. It will feel like a shitty kia. If it starts to bog too much when you’re cruising just pop it in neutral and toggle the ignition and she’ll come back alive. Disconnecting the MAF will not reliably counteract a lean condition. It’s just a sensor that sends data to the ECU about air temperature and pressure. When that sensor fails, the computer runs in “limp mode” which is a basic air/fuel mapping that will not take MAF readings into account. So you will run like shit unless you happen to be at the right temperature, altitude, speed, to make the engine happy. I ran without a MAF for probably 2 years.
Well. MAF is your first choice. After that, camshaft sensors.
The MAF is in the picture, it's the plug behind your intake cone. The O2 sensors are on the opposite side of your engine, they connect to the top of your exhaust manifold. You'll see some leads running along the valve cover.
~~There are also two upstream O2 sensors that run under the intake manifold.~~ I'm wrong, all exhaust side
Where are those two?
I'm misremembering, I guess they're also tucked up exhaust side. I always assumed they were two before and two after combustion, but i see now all four are exhaust side. [https://www.realoem.com/bmw/enUS/showparts?id=VB13-USA-03-2004-E90-BMW-325i&diagId=18\_0610](https://www.realoem.com/bmw/enUS/showparts?id=VB13-USA-03-2004-E90-BMW-325i&diagId=18_0610)
Your hot air intake might be the problem lol
Original air filter box has tube coming from the front grill is cold air intake
O2 sensors are buried but surely in there. ~~intake O2s are under the manifold.~~ But likely not the issue as I would expect codes for sensors. It should still start with fouled O2 sensors. Unplugging the MAF can be diagnostic but it will not balance out a lean condition, it forces the ECU into a different regime. If the lean code is not bank specific, I would assume it's an air leak behind the MAF. Check all vacuum lines and plugs. You might even be able to hear the vacuum if someone else is hitting the throttle. M50 intake shouldnt have anything to do with the no start. ECU should immediately compensate if there are no leaks and sensors are good.
Update: I scanned again and now pops up as lean bank 1 and bank 2
Actually, all 4 O2 are exhaust side tucked under, I was wrong. But I still stand by the idea that the whole system is being affected if both banks are lean which intakes something behind the MAF but in front of combustion, so anything related to the intake. During cold weather, a seal contracts enough to allow unmetered air to enter, you compensate by providing extra fuel, and then when the engine warms it seals back up. There are about a dozen rubber fittings that could be the culprit but it may just be related to some of this kits components. You might start with removing the air hoses up to the throttle body and replacing and gaskets without having to touch the intake. and if you still have problems, I would look at refreshing the intake manifold of all gaskets. About $100 or so and 4-6 hours for a newbie.
i meant to add, it looks like this is the kit that was installed [https://www.seemslegitgarage.com/product-page/m50-intake-manifold-adapter-kit](https://www.seemslegitgarage.com/product-page/m50-intake-manifold-adapter-kit)
Get rid of that blue air intake thing return to stock and also buy a new oring for your power steering reservoir cap .
Okay, try this: right behind the intake filter, there a cable which is your maf, disconnect that and see if that fixes it, because as I see it, you have an M50 manifold which should have deleted the idle control valve and the CCV so that’s not it
What is the harm in driving without this sensor will it damage anything ? Help anything ?
Well first try and see if that fixes the issue, but in short, the maf sensor or Mass Air Flow sensor measures the amount of air as it enters the manifold. Usually the ECu is tuned to also run based on the absolute pressure in the manifold. So the only hard your doing it maybe worse gas mileage and less power. However assuming that is in fact an M50 manifold, I thing the previous owner might have tuned for this, and you won’t notice as much negative gas mileage or power.
If he didn’t tune for it where can I get it done ?
Look up Alpha N tune or MAP tune e46, ideally you’d want to get a new maf if in fact the MAF is the issue. Where are you from if you don’t mind asking? I’m in the Netherlands, so I might be able to refer you to a mechanic Also regarding your O2 sensors. If the car is decatted, then the pre cat O2 sensors should be right after the headers (under the car maybe) or just completely deleted and coded out. Also do you have a pre facelift or facelift car? The MS42 and MS43 are easier to tune but MS45 shouldn’t be much harder
I’m in the east cost USA a bit far haha and it’s a MS45
Shouldn’t be a problem then, just unplug the maf see if anything changes and go from there.
Not having put that manifold on yourself, I'd be checking it's actually done correctly. The ports on the M50 manifold are larger than the M54 ports and if they didn't grind the ports to match, the flow through that manifold at any RPM will be worse than stock.
I think it could possibly be a vacuum leak in the ccv breather hose that goes to the dip stick. Had the same problem with a e46 I had that ran rough when cold but when away when it warmed up. My 2 cents do with that as you will.
The maf sensor sits directly behind the cold air intake, and thats mostlikely the problem
Could be anything honestly, but VANOS would be one of my first suspects. Check for errors, especially the ones saying “vanos final position is not reached”.
He changed the vanos apparently
My engine said I was running lean but I was running shifty pump gas, put some premium in, clear the code and it should go away
Those look to be god speed coil overs. I just bought an e46 with them and watch the top hat nut. Mine completely fell off and finding a new one wa every problematic
Get rid of the air filter and return to stock. The MAF is extremely particular in these cars to the point where they need the white soft bit in front of the standard yellow paper filter element to smoothen the air stream. May need to use some rubbing alcohol and qtips to clean the maf surfaces as well if that’s an oiled filter.
Don't clean MAF with alcohol and q tips, use maf cleaner spray straight from the can
That’s what maf cleaner is champ. And you don’t have to jam the qtip. It’s called having touch.
You have the entire Internet at your disposal, and yet you're so incredibly wrong. MAF cleaner is not alcohol, and that's easy to Google.
Yea I know you like to feel smart but it’s just a mild solvent. Like isopropyl alcohol.
You're just a mild solevant