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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N57 / M57 Turbo Diesel Discussions - 335d > 335d MAF reading appears low



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      01-22-2019, 02:20 PM   #1
cb21rf
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335d MAF reading appears low

Hello all - first off - thanks to everyone who replied about my DPF issue. The thermostat was bad and replacing it led to a beautiful regen cycle that cleaned it all up.

I've noticed that my 335d (95k miles) still runs a little sluggish. Installed a scanner app that has some pretty cool actual vs expected readings (the expected readings are straight from the ECU) for both boost and air mass.

I've noticed the air mass readings I'm getting are 25-40% below expected, pretty consistently. Boost seems very close to expected.

Here's what I'm thinking of doing but wanted to get some opinions:
1) Clean the MAF - bought some CRC cleaner and will clean the MAF, then see if that changes anything on the air mass readings. I haven't been getting any stalling, rough starts, or bad idling, though. Just the sluggish performance at lower RPMs.

2) If #1 doesn't really help - do the walnut blasting

Any thoughts or opinions would be most helpful!

Andrew
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      01-22-2019, 03:39 PM   #2
Persian Whisperjet
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FYI OEM replacement MAFs are sometimes available for cheep -- I got mine from ECS on sale last year for like $50.
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      01-23-2019, 05:30 AM   #3
ground_zero
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I'm not sure how much this plays a part but when was the last time you changed your air filter? it seemed to have made a difference on my end.
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      01-23-2019, 01:52 PM   #4
cb21rf
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Thanks, both! I'm going to clean the MAF and replace the air filter, then see if it makes any difference!
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      01-23-2019, 02:07 PM   #5
Thecastle
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I'll also mention that the MAF sensors on these cars seem to wear much faster than other vehicles and are more prone to failure. I've been through several at the dealer under warranty.
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      01-24-2019, 01:36 AM   #6
335dlci
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Quote:
Originally Posted by cb21rf View Post
Thanks, both! I'm going to clean the MAF and replace the air filter, then see if it makes any difference!
Cleaning never works..
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      01-24-2019, 12:02 PM   #7
cb21rf
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Quote:
Originally Posted by 335dlci View Post
Cleaning never works..
replace the MAF sensor altogether?
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      01-24-2019, 12:06 PM   #8
335dlci
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Quote:
Originally Posted by cb21rf View Post
replace the MAF sensor altogether?
Yea. Mafs issues have been discussed many times and are problematic. Replace. They were 50$ when I bought a couple spares..
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      01-24-2019, 07:33 PM   #9
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That was a fire sale price, they are now back up to ~$200 USD. I see that AArod has some at tune my euro for $60 though, might as well snatch one up while you can.
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      01-25-2019, 12:51 AM   #10
cb21rf
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Originally Posted by Owen81 View Post
That was a fire sale price, they are now back up to ~$200 USD. I see that AArod has some at tune my euro for $60 though, might as well snatch one up while you can.
Thanks for the tip! Ordered one!
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      01-26-2019, 12:21 PM   #11
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Another thing to add to my to do list.
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