[Yozh]

The purpose of this thread is to examine an option of expanding our alphabet, or deletes thereof.

MY MAF is caput. 2K miles ago I cleaned it with proper spay and reset the adaptations. Result was a slight improvement to the performance, but still lackluster. What was curious, that every time the thing was unplugged, next keycycle was great, later returning to a blah drive.

So I have monitored the thing. When it is online the performance suffers, when it's temperature flatlines, it takes with it a major change in mass airflow setpoint, but performance is great. As soon as it kicks back in any form, it is like someone slammed the brakes.

As such, there is a default map that kicks in when MAF goes off. This is what is written in the Diesel Technology Manual:

...The HFM 6.4 measures the air mass intake within very close tolerances so as to permit precise control of the exhaust gas recirculation
as well as optimum configuration of the smoke limit. This is important for complying with current and future emission limits...

...The HFM measures
the air mass taken in by the engine. This is used to record the
actual air mass, which in turn is used to calculate the exhaust gas
recirculation rate and the fuel limit volume...

...The charge-air temperature is used as a substitute value for calculating
the air mass. This is used to check the plausibility of the
value of the HFM. If the HFM fails, the substitute value is used to
calculate the fuel flow measurement and the EGR rate...

So, BMW has built a redundant system to make sure emissions are never exceeded. For those of us that already have the EGR added to the vocabulary, MAF is a natural to follow. My question is, has anyone (BPC, JR) figured a way to add the MAF to out linguistic abilities. It is such a fragile and expensive piece of equipment, plus not having one would give us more intake modification options.

PS: tried searching

[BB_cuda]

Seems like I remember the advanced guys discussing that MAF could be removed in tunes. Dare I say that I remember Bob@BPC talking about this.

[Yozh]

Originally Posted by BB_cuda

Seems like I remember the advanced guys discussing that MAF could be removed in tunes. Dare I say that I remember Bob@BPC talking about this.

I remember that too, but I'm on JR and would be nice if there would be a common solution.

[iaknown]

Jarek was close to getting the MAF deleted. We'll have to hound him when he gets back.....

[335dlci]

Originally Posted by BB_cuda

Seems like I remember the advanced guys discussing that MAF could be removed in tunes. Dare I say that I remember Bob@BPC talking about this.

He did post a video with it unplugged while the engine was at idle and revving up with no CEL.

[Hockey13]

Originally Posted by 335dlci

He did post a video with it unplugged while the engine was at idle and revving up with no CEL.

well, if you have say a jr 2.5 tune will full delete... could you run with it unplugged without causing any harm? I mean if it's just to see if a cel is activated without causing harm why not try for a period of time and see...?

[Yozh]

With a JR Tune one gets a SES and Limp Mode. Plus I would think that maps would have to be optimized anyway. Learning the new MAF would be so good. Jarek though, has seemed to go MIA, I hope he's somewhere on a Cuban beach drinking his cervezas i mojitos.

[k335d]

Here you go sir.

[smass]

See if you can get a copy of SI B13 06 16. It applies to some X5d. It may explain why your MAF is not consistent. "Replace the hot film mass airflow sensor (HFM) because internal tolerances do not meet specification" is all I have found so far.

[Thecastle]

Yes, the MAF on these cars seem prone to off nominal reading. I dunno why it is, as MAF is a pretty simple and common technology. I've had mine replaced 4 times for under warranty, and each time the car runs substantially better once it's replaced, especially fuel economy. most recently had mine replaced again a week ago and before the best I could do was about 28mpg around town and now I'm consistently getting 32-33mpg.

BTW my car is back after its most recent tour of the service bay

From what I read, when I was trying to diagnoise my 4862/48d1 errors is that BMW Mafs fail with regularity, and can be a source of egr/dpf errors. The reason being is that if the air flow rate is mis read, it triggers bad calculations for predicted flow rates through the egr and dpf

The master tech replaced mine again in an attempt to correct my ses. It didn't work but the car runs better. We'll see if the latest round of parts replacements keeps my car ses free. If all,is well I plan to tune it,mans do an abc delete.

[shnaggs]

Bpc does have a MAF delete tune. I was going to get this done along with a stage 2+, but I have been waiting for iaknowns exhaust to show up. Looks like the time is nearing the end for me. Can't wait.

[ideloera]

The MAF can be completely tuned out, talk to Bob @ BPC. I spoke to him about this in person about 1 month ago when I took my car in for the deletes. He did say that for better fuel efficiency it is best to operate the car with the MAF on/installed.

[Thecastle]

Just a thought...

I wonder if the MAF sensor unreliability in these cars is part of the cause of the rapid carbon build up we've seen on some cars. When I replaced mine, I saw an immediate increase in fuel economy each time, which might indicate less fuel being injected when the maf is working as it should.

I suspect the MAF's are indicating a higher flow rate of air into then engine than is actually flowing in. With the MAF over reporting air flow, the car thinks more 02 is available to the engine, and possibly runs larger amounts of EGR to compensate, or may trick it to inject more fuel into the combustion chamber. In either case the air/fuel ratio's are off inside the combustion chamber, generally there is less 02 than the engine expects. Thus, the DDE over injects fuel, with less than optimal amounts of air, combustion quality suffers and you end up with more unburnt fuel i.e. lower economy, more soot, and faster CBU.

I maybe completely off here.

[iaknown]

Originally Posted by shnaggs

Bpc does have a MAF delete tune. I was going to get this done along with a stage 2+, but I have been waiting for iaknowns exhaust to show up. Looks like the time is nearing the end for me. Can't wait.

You haven't been following the exhaust teaser thread have you?

[shnaggs]

Originally Posted by iaknown

You haven't been following the exhaust teaser thread have you?

I guess not closely enough

Will be contacting you shortly

[WreckerX5d]

Originally Posted by ideloera

The MAF can be completely tuned out, talk to Bob @ BPC. I spoke to him about this in person about 1 month ago when I took my car in for the deletes. He did say that for better fuel efficiency it is best to operate the car with the MAF on/installed.

I concur. I believe Bob tested the MAFing and MAFlessness on 335dsleeper's car and concluded that it's best to leave it on for daily driving.

[lnxguy]

MAP based smoke limiter, no reason why you can do this on the 335d. VW TDI guys have been doing it for years.

[Mrdeezy]

taking off the MAF on any car designed to have it is not a good idea.

[lnxguy]

Originally Posted by Mrdeezy

taking off the MAF on any car designed to have it is not a good idea.

Why's that exactly? If it's tuned to run off the MAP instead, what are the downfalls? This is pretty common in the diesel world.

[TheHolyCobra]

Originally Posted by lnxguy

Why's that exactly? If it's tuned to run off the MAP instead, what are the downfalls? This is pretty common in the diesel world.

+1

Diesels and their corresponding power are regulated by fuel. If you don't provide enough fuel, the motor just doesn't make as much power. No engine-busting detonation to worry about. So deleting the MAF, especially in a MAP sensor based car like lnxguy said, is do-able with proper tuning.

In the gasser world, if you don't provide enough fuel, then the motor goes BOOM. Pre-ignition and detonation can wreck havoc on internals. Hence why a properly working MAF is critical to a healthy running engine...unless you are running a MAP based engine control system and/or standalone engine management system.

[335duff]

My car seems to run pretty much fine with no MAF? The way i diagnose faulty maf is to unplug it and run the car, if it runs better replace maf. Without the hfm, the engine runs in a "safe" condition. This means reduced power and mpg. My car seems to churn through a sensor in about 25k-35k miles.

Edit: Are people using genuine bmw maf (~$400 from dealer) or the non-bmw bosch one (~$200, fcpeuro or similar)? I've had two replacement bmw ones under warranty and have the bosch on the car now. So far it seems the same? The two parts are visually identical, same part numbers etc. Is the only difference the box they come in?

[smass]

Originally Posted by 335duff

Edit: Are people using genuine bmw maf (~$400 from dealer) or the non-bmw bosch one (~$200, fcpeuro or similar)? I've had two replacement bmw ones under warranty and have the bosch on the car now. So far it seems the same? The two parts are visually identical, same part numbers etc. Is the only difference the box they come in?

Rock Auto has the Bosch one for $193. Did yours fail with a code or just lower than normal power?

thanks