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sly · 11-14-2018, 05:53 PM

Thank you very much for the replies. I have ordered a new MAF in the hopes that will make a difference. I played around with it last night. I took apart the intake hose and air cleaner box to look for any deformities or holes. Everything looked good. When I put it back together I forgot to plug in the MAF. Started the car and let it idle. Noticed the fuel trims were at 0. But the idle was high. Got a CEL and realized I left the MAF unplugged.

Plugged in the MAF and cleared the code. Restarted and immediately got a MAF low flow ECU code. Reset the ECU and tried again. Let it idle and the trims eventually crept back up to where they were at about 30%.

Is it normal for fuel trims to return to 0 with the MAF unplugged? I assume the car was basically in Open Loop mode and was relying off the map. Running map fuel curves, the ECU did not need to trim the fuel requirements. But I did get a CEL.

So based upon the advice here, I ordered a new MAF. I will also look harder this weekend for exhaust leaks. I did hit a rock a few weeks ago that left a small dent in my resonator downstream of the header. Maybe the jarring force was enough to crack the stock header. Hard part is getting those heat shields off.

Thanks for everything. I'll update once I find something out.

11-14-2018, 05:53 PM	#9
sly Senior Member Join Date: Dec 2015 Drives: 2016 Cosworth 2.2 BRZ Location: TN Posts: 335 Thanks: 89 Thanked 198 Times in 124 Posts Mentioned: 10 Post(s) Tagged: 0 Thread(s)	Thank you very much for the replies. I have ordered a new MAF in the hopes that will make a difference. I played around with it last night. I took apart the intake hose and air cleaner box to look for any deformities or holes. Everything looked good. When I put it back together I forgot to plug in the MAF. Started the car and let it idle. Noticed the fuel trims were at 0. But the idle was high. Got a CEL and realized I left the MAF unplugged. Plugged in the MAF and cleared the code. Restarted and immediately got a MAF low flow ECU code. Reset the ECU and tried again. Let it idle and the trims eventually crept back up to where they were at about 30%. Is it normal for fuel trims to return to 0 with the MAF unplugged? I assume the car was basically in Open Loop mode and was relying off the map. Running map fuel curves, the ECU did not need to trim the fuel requirements. But I did get a CEL. So based upon the advice here, I ordered a new MAF. I will also look harder this weekend for exhaust leaks. I did hit a rock a few weeks ago that left a small dent in my resonator downstream of the header. Maybe the jarring force was enough to crack the stock header. Hard part is getting those heat shields off. Thanks for everything. I'll update once I find something out.