Idling characteristics with bad MAF sensor? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

mheffel · 10-21-2014, 01:35 PM

Does anyone know how an otherwise good running BRZ idles when the MAF sensor is bad or just disconnected? I think a piece of debris may have gotten sucked into my intake (embarrassing story) and ruined my MAF sensor. At idle my engine oscillates between 600 and 2200 rpm (about a 1 second frequency). It's not running good at all.

Thanks, Mike

zkv476 · 10-23-2014, 01:36 AM

From experience the car should idle fine with the MAF disconnected, maybe a little rougher but it wouldn't be fluctuating like that. Typically people know a MAF is bad when the car runs better with it disconnected, signifying the MAF is giving a bad reading. I wouldn't drive without the MAF but you can start it up disconnected to get an idea. Was it large debris that would have impacted the sensor or just made it dirty?

mheffel · 10-25-2014, 08:08 PM

I disconnected the MAF, and the idle was still bad, so I figured the MAF was OK, per your advice. So, I moved up the air intake to the throttle body. I removed the flexible intake tube at the throttle body and after opening the throttle by hand found a 1/2" sliver of loose plastic. I removed it, and now the car runs perfectly again. I suppose the debris was somehow interfering with the throttle or throttle position sensor.

Turdinator · 10-26-2014, 08:32 PM

Quote:

Originally Posted by mheffel

I disconnected the MAF, and the idle was still bad, so I figured the MAF was OK, per your advice. So, I moved up the air intake to the throttle body. I removed the flexible intake tube at the throttle body and after opening the throttle by hand found a 1/2" sliver of loose plastic. I removed it, and now the car runs perfectly again. I suppose the debris was somehow interfering with the throttle or throttle position sensor.

That is scary. What was the plastic from? Could more of it have gone through your motor?

Ultramaroon · 10-26-2014, 10:43 PM

Time to fess up. What did you do?

edeekeos · 10-26-2014, 10:56 PM

eeek, this sounds scary..

hope nothing made its way inside..

10-21-2014, 01:35 PM	#1
mheffel Junior Member Join Date: Aug 2013 Drives: BMW Z3, Mercedes CLK430, Subaru BRZ Location: Alabama Posts: 7 Thanks: 0 Thanked 0 Times in 0 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Idling characteristics with bad MAF sensor? Does anyone know how an otherwise good running BRZ idles when the MAF sensor is bad or just disconnected? I think a piece of debris may have gotten sucked into my intake (embarrassing story) and ruined my MAF sensor. At idle my engine oscillates between 600 and 2200 rpm (about a 1 second frequency). It's not running good at all. Thanks, Mike

10-23-2014, 01:36 AM	#2
zkv476 Senior Member Join Date: May 2014 Drives: 2014 SWP BRZ, MT Location: New Jersey Posts: 240 Thanks: 11 Thanked 140 Times in 90 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	From experience the car should idle fine with the MAF disconnected, maybe a little rougher but it wouldn't be fluctuating like that. Typically people know a MAF is bad when the car runs better with it disconnected, signifying the MAF is giving a bad reading. I wouldn't drive without the MAF but you can start it up disconnected to get an idea. Was it large debris that would have impacted the sensor or just made it dirty? __________________ The answer is racecar. Always.

10-26-2014, 10:43 PM	#5
Ultramaroon not playing cards Join Date: Sep 2014 Drives: a 13 e8h frs Location: vantucky, wa Posts: 32,395 Thanks: 53,053 Thanked 37,228 Times in 19,308 Posts Mentioned: 1117 Post(s) Tagged: 9 Thread(s)	Time to fess up. What did you do? __________________ service manuals

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10-25-2014, 08:08 PM	#3
mheffel Junior Member Join Date: Aug 2013 Drives: BMW Z3, Mercedes CLK430, Subaru BRZ Location: Alabama Posts: 7 Thanks: 0 Thanked 0 Times in 0 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	I disconnected the MAF, and the idle was still bad, so I figured the MAF was OK, per your advice. So, I moved up the air intake to the throttle body. I removed the flexible intake tube at the throttle body and after opening the throttle by hand found a 1/2" sliver of loose plastic. I removed it, and now the car runs perfectly again. I suppose the debris was somehow interfering with the throttle or throttle position sensor.

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