2007 corolla P0171

[HyundaiAbuser]

Hello fellow bitogers,

i have a 2007 corolla with 145k miles that is throwing the P0171 bank 1 running lean code. The car runs just fine and has no issues with acceleration or drivability but the trim numbers bug me.
Checking the fuel trims they are +32% at idle and go up to +44% when at 1800 rpm or above but that's where it maxes out.
The increase in fuel trim with increased rpm has pointed me away from a vacuum leak although i still did a smoke test and came back with nothing.
There's been a new set of injectors without change
fuel pressure test shows 44psi with the vehicle on and stays consistent with revving just before the fuel rail and holds pressure well
Maf sensor has been cleaned and reads 2.2ish g/s at idle (possibly high?) and 15-17ish at 2200 rpm
The Air fuel ratio sensor reads in the normal range of around 3.1-3.5v resting around 3.3 mostly
the Air fuel equivalence ratio stays around 14.5-15 (isnt ideal 14.7?)

I'm thinking possibly an exhaust leak in front of the front o2/AF ratio sensor but haven't checked yet

what say yee experts?

 

[Rand]

Is it possible there is an air leak after the maf? 2007 crank in plastic somewhere?

@Trav might have some better ideas?

 

[HyundaiAbuser]

Is it possible there is an air leak after the maf? 2007 crank in plastic somewhere?

@Trav might have some better ideas?

i smoke machined it and sprayed carb cleaner around every hose, injector seal and connection that i could find thats supposed to seal although its not out of the question

 

[incognito_2u]

Original intake manifold gasket

 

[HyundaiAbuser]

Original intake manifold gasket

Also replaced

 

[Rand]

Possessed?

Running out of ideas here.. how much are decent O2 sensor(s)?
Maybe not quite parts canon time.

 

[HyundaiAbuser]

Possessed?

Running out of ideas here.. how much are decent O2 sensor(s)?
Maybe not quite parts canon time.

Amazon price for denso was 100 bucks, the general Census was to not use aftermarket

 

[michaelluscher]

You've already done smoke test and injectors
I'd say check the fuel pump, but you did that already
I'd smoke test the exhaust, probably the front donut gasket
I've been there, done this with my 2AZ xB, but I threw parts at it
If we go on the preconceived belief that a MAF should report roughly the engines displacement at idle, yours seems a little high, this being a 1.8 1ZZ-FE
I'd smoke test both intake and exhaust, just in case you missed something
How's the PCV valve and hose?
TSBs or PCM reflashes maybe?
Purge valve sticking?

Only Denso parts, for either AFR or MAF
Amazon can be sus, RockAuto would be a safer choice

 

[HyundaiAbuser]

You've already done smoke test and injectors
I'd say check the fuel pump, but you did that already
I'd smoke test the exhaust, probably the front donut gasket
I've been there, done this with my 2AZ xB, but I threw parts at it
If we go on the preconceived belief that a MAF should report roughly the engines displacement at idle, yours seems a little high, this being a 1.8 1ZZ-FE
I'd smoke test both intake and exhaust, just in case you missed something
How's the PCV valve and hose?
TSBs or PCM reflashes maybe?
Purge valve sticking?

Only Denso parts, for either AFR or MAF
Amazon can be sus, RockAuto would be a safer choice

Early next week I plan on smoke testing the exhaust. I replaced the pcv valve with oem and the hose has no noticeable leaks and hasn’t collapsed. The Corolla forum folks of past were stating their maf readings at idle were around 1.5-1.7 ish

 

[Trav]

When smoke checking the exhaust be sure to move the exhaust system around and check any brackets welded to the pipe(s) anywhere near the cats and O2 sensors,

 

[HyundaiAbuser]

When smoke checking the exhaust be sure to move the exhaust system around and check any brackets welded to the pipe(s) anywhere near the cats and O2 sensors,

I’m going to do a positive pressure soapy water test as well as that I’ll be sure to

 

[Luftmasse]

What are your fuel trims and calculated load at wide open throttle?

 

[HyundaiAbuser]

Load was 65% with fuel trim of +44.73

 

[SatinSilver]

Also replaced

Did you use the updated orange colored gasket? I'd check the air intake hose carefully for cracks at this age. Also a new throttle body gasket if that hasn't been done. As mentioned the front exhaust donut gasket is a big culprit on these.

 

[HyundaiAbuser]

Did you use the updated orange colored gasket? I'd check the air intake hose carefully for cracks at this age. Also a new throttle body gasket if that hasn't been done. As mentioned the front exhaust donut gasket is a big culprit on these.

I’ll add those to the list and update when done. I did use the updated part

 

[Luftmasse]

Load was 65% with fuel trim of +44.73

Classic sign of a misreporting MAF.

You need a new MAF sensor.

 

[michaelluscher]

Classic sign of a misreporting MAF.

You need a new MAF sensor.

NO parts store crap
Denso only

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