2010 Subaru Forester 2.5L X ( Mass air flow/ Intake Air Temp Sensor issue)

2010 Subaru Forester 145,000 miles. Check engine light, traction light on, cruise flashing started it all.
Code was p0102, p0113 and cylinder 4 misfire

Symptoms:
Run slightly erratically, have less power and idle inconsistently.

When I did my inspection... I found my sparks plug #4 soaking with oil but all spark plug has oil. Obviously I need the valve cover gasket replaced.

What is did first:

New 4 spark plugs
New cables
New valve cover gasket and spark plug seal

This didn't solve the problem so I check the resistance of the ignition coil and the value wasn't identical which my research say they should read equal. They are 10 ohms apart so I got a new one.

Second thing I did:

New Ignition coil

third thing I did:

4 new Fuel Injectors ( I wasn't worried about replacing it because 145,000 miles probably needs cleaning. Rebuilt one is cheap)

This still didn't fix the problem. I move on to more testing and things are getting expensive. Mass air flow/ Intake air temp sensor is next but please look at my scan tool reading.



This was taken when the Mass air flow/ Intake air temp sensor 2 in 1 was unplugged. The car runs and starts



This was taken when the Mass air flow/ Intake air temp sensor 2 in 1 was plugged. The car runs and starts

My Voltage test on the connector shows 12V
The resistance test for IAT begins with 1.3 ohms cold and after 15 min idle with over 100 degree temp the reading is 1.0 ohms.

Anybody familiar with this problem? I need to know if the Mass air flow/ Intake air temp sensor is the culprit. Please let me know if I need a certain test to verify the culprit

Thanks

dazs, since you started working on the vehicle, which codes have reset? Do the Roughness Monitor PIDs ever count up with the engine idling?

Since you've already done the secondary ignition system and the injectors, I'd be more suspicious of an engine mechanical problem. The easiest way to check this would be an audible relative compression test. Starting with a fully charged battery, disconnect all four injectors and crank the engine while listening carefully to the cranking cadence of the engine. Take a video and post it if you're in doubt.

This recent video from ScannerDanner is a good example. Don't worry about the scope capture, just the sound of the engine during cranking:

Update!

I was really planning to delaying the compression test but I did a standard compression test
Dry Compression test
Cylinder 1= 180 psi
Cylinder 2= 175 psi
Cylinder 3= 180 psi
Cylinder 4= 75 psi

Wet compression test
Cylinder 4= 90 psi

That explains the Misfire on Cylinder 4

Solution: I just added a can of Engine Restore in the engine oil and see what happens after miles of driving.

Still a problem is trouble code P0113 and P0102

Like my bench test for my Mass air flow/ Intake Air Temp Sensor

IAT Bench Test:
I have a resistance of 1.3 K/ohms @ cold, room temp and drop to 1.1- .8 with a hair dryer or in the car after 15 minutes idle.

Anybody can tell me for sure my sensor is bad with actual spec for 2010 subaru forester 2.5l. I been looking everywhere for the correct range for a Subaru. I've seen available range online but it's not for a 2010 Subaru Forester.

Thanks

dazs wrote:

I have a resistance of 1.3 K/ohms @ cold, room temp and drop to 1.1- .8 with a hair dryer or in the car after 15 minutes idle.

Anybody can tell me for sure my sensor is bad with actual spec for 2010 subaru forester 2.5l. I been looking everywhere for the correct range for a Subaru. I've seen available range online but it's not for a 2010 Subaru Forester.

I don't know the resistance range of that sensor off the top of my head, but I do know that the screenshot you posted with the IAT plugged in showed a reading of 114 degrees, which is completely rational IMO. The behavior of the resistance during your bench test also sounds rational.

That's why I was asking how often P0113 and P0102 reset. Because it sure sounds like they're intermittent faults, rather than the result of an out-of-range sensor.