New MAF sensor trouble

[Cutler]

Hello guys,

Have had a bit of issues with MAF sensor so I am seeking some advice/help. I know BOSCH sensor is the best one to go with, but, I bought a MAPCO sensor. Before getting all the comments on how it's no good, I wanted to point out that MAPCO is a German company which produces quality products so I did not cheap out on some of the cheap Chinese or e-bay sensors.

Nevertheless, the car is still acting weird for some reason. For example, if I floor it, it starts to get going and once the RPM's climb it starts shaking back and forth (resembles something like a beginner who is learning to use the clutch but at higher speeds) and all the power is gone and it resists speeding up unless I use the clutch again.
The weird thing is, if I ease into the acceleration and use the pedal moderately, it seems to be doing fine and speeds up just fine.

Does the MAF need some KM's to accommodate to the throttle and sense the right amount of air/fuel? Perhaps a vacuum leak somewhere? Maybe someone has had something similar to what I described?

I will appreciate all the answers, thank you beforehand.

[MarcoZandrini]

No, the MAF is a sensor. It has no memory or adaptability. Why did you replace the original MAF? What were the codes? Just because the MAF is made in Germany doesn't mean that it's a quality part. The only brand of MAF I trust is Siemens/VDO.

[Cutler]

Because it was having some trouble before so I decided to clean it but then it failed completely so I bought a new one. The codes that I got were P0111 and P0101, I cleared them yesterday and will plug the OBD shortly to do another check.

I mean worst case scenario I can just return it back and buy the original BOSCH if it turns out that indeed the sensor is the problem.

EDIT: Just scanned it, no codes at all so that makes it even more weird. Going over all the connections and intake to make sure everything is connected properly and there is no vacuum leak anywhere.

EDIT: All the connections are good and seems like there is no vacuum leak. But, when revving it up, it seems like it has a bit of a misfire but not too noticeable.

[randy72877]

Check the fuel pressure. Drive with a pressure gauge connected

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[Cutler]

So you're suggesting it might be the fault of fuel pump?

[dworthy]

Or a clogged fuel filter.

More info is needed as the two codes you posted would point me to a vacuum leak, not a misfire, as that isn't one of the codes that is posted.

[Cutler]

Yeah I wish I had more info myself but those two were the only codes I had.

Just now when I went out for a drive it was doing it again. pressing the accelerator pedal down it starts to accelerate and then completely falls to its face and all the power is completely gone so the accelerator pedal literally does not have any response. Then, after depressing clutch everything goes back to start.

I will keep scanning to hopefully find some codes that can lead to a solution.

[randy72877]

How does it run with the maf disconnected?

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[Cutler]

I ran it without MAF for 3-4 days before the new one arrived but have yet to test it again without the new MAF. Will do that tomorrow as well as diagnose it again. Thanks for all the help so far!

[randy72877]

So your problem started after you replaced the maf? What brand did you get?

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[Cutler]

Well with the MAF disconnected the car obviously lost some power especially in the high end and felt sluggish but I had nothing like I described. This started happening after I put in the new MAF sensor from MAPCO, cost me $75 so a bit cheaper than BOSCH.

I will try to run it without the sensor today and see if it runs the same as before, then report back here.

[Cutler]

So, took it out for a drive just now and got some mass air flow data.
1. Right upon start up - 4,4 g/s ; 0,6 lb/min

2. After driving easy for 10 minutes - 2,72 g/s; 0,4 lb/min

3. After some spirited driving, flooring it a couple of times- 2,61 g/s; 0,3lb/min

So are these values normal and within the standard or are they lower than they are supposed to be? Appreciate all the help!

[charter21p5]

Those values look low to me from the last time I was troubleshooting a similar issue. Get rid of the Mapco maf and put a genuine maf back in...

[Cutler]

Those values look low to me from the last time I was troubleshooting a similar issue. Get rid of the Mapco maf and put a genuine maf back in...

Can anybody confirm this with some data (g/s or lb/min) for the BOSCH maf sensor? Whether the numbers I provided are indeed low?

[charter21p5]

Not being rude go look at my other responses. These off brand parts are crap unless you are buying Meyle, Bosch, or another reputable manufacturer etc. it's always the same story.. someone trying to go cheap buying aftermarket cheap brand parts to save a buck and then they post on the forum asking why the car is now having more issues. Buy genuine parts unless it is a vendor that makes the part for BMW.

[Cutler]

Not being rude go look at my other responses. These off brand parts are crap unless you are buying Meyle, Bosch, or another reputable manufacturer etc. it's always the same story.. someone trying to go cheap buying aftermarket cheap brand parts to save a buck and then they post on the forum asking why the car is now having more issues. Buy genuine parts unless it is a vendor that makes the part for BMW.

yes of course, thank you for the honest input, think I will return the MAPCO one and buy a genuine BOSCH, see if that fixes the problem or not.

[charter21p5]

This thread reminds me I need to baseline the airflow numbers on my e46 so I have a reference when needed. Those numbers will vary based on many factors such as elevation, outside air temp etc. I am curious what product did you use to clean your old maf? I have used both brakleen and maf cleaner. I have heard not to use brakleen and only use maf cleaner. I now only use maf cleaner however never had an issue with brakleen.

[Cutler]

I just used something similar to a brake cleaner as well, I guess it was a little too rough for the sensor so it refused to work at all. I am returning the MAPCO sensor and have purchased the OEM Bosch already so it's on its way. Fingers crossed that it will solve this weird problem, will report once it's installed.

[dworthy]

Please don't use Brakekleen on the MAF, as it is too harsh on the sensor.

Let us know how the new sensor turns out.

[Cutler]

I am happy to share this post with you as the BOSCH MAF sensor finally got delivered today and I installed it right away. Fortunately, the problem is gone and there is no more shaking, can finally floor it and it doesn't hesitate so I am quite happy.

In addition, bought a Bosch air filter as well since I didn't know when the last one was changed. Thanks guys for all the help, now I just hope that the Mapco sensor will get accepted as return and the money will be refunded!

[dworthy]

Thank-you for coming back and letting us know how it turned out.

Regular maintenance will keep that car running for many year.

[Cutler]

Agreed, going to try to preserve this car for as long as possible, even though it's one of the weaker engines it is still tons of fun and is one of the best vehicles I have driven in my life.

Maybe do a S54 swap in a couple of years just to change it up and keep it fun haha

[dworthy]

Yeah, an S-54 is plenty of fun!

The better bet, and maybe easier would be to toss in a M54 B30/B25 motor and F/I it. You wouldn't have much issues with the driveline as they would be similar vers the S-54. Sure the M-43TU is a bit weaker, but it doesn't have the chain problem as the newer 4-cylinders.