MAF sensor readings

[LazyDog]

Since the best way to learn something new is when checking those items while the car is having no problems/ money light.

I recently have been checking the car w/ LIVE DATA function on the Jetta and trying to make sense of the MAF Reading:

1. At start up ambient temperature of 70F, I get 4.25g/ sec

2 After it just reaches 190F, I get 3.00g/ sec

All reading at IDLE 690 rpm's

Any good rules that you can apply???

 

[Duffyjr]

When it first starts isn't it in open loop and cold, so it would make since it's sucking more air

 

[LazyDog]

When it first starts isn't it in open loop and cold, so it would make since it's sucking more air

Yes it probably is in open loop. It will be nice to find what the readings should be at different rpm's!!!!

 

[Trav]

This may help.

https://support.alldata.com/sites/main/files/file-attachments/maf_sensor_testing_110918.pdf

 

[LazyDog]

This may help.

https://support.alldata.com/sites/main/files/file-attachments/maf_sensor_testing_110918.pdf

Thanks for the link, I'll try this on my 3 cars and see what are the results.

 

[Leo99]

Really smart to look at what's normal so you can detect what's abnormal. My older car threw a O2 sensor code and I could look at the voltages on my OBD2 reader but I couldn't tell if they were normal or not. They didn't look like the normal waves I saw on the Internet but they didn't look like the abnormal waves, either.

 

[Jetronic]

Since the best way to learn something new is when checking those items while the car is having no problems/ money light.

I recently have been checking the car w/ LIVE DATA function on the Jetta and trying to make sense of the MAF Reading:

1. At start up ambient temperature of 70F, I get 4.25g/ sec

2 After it just reaches 190F, I get 3.00g/ sec

All reading at IDLE 690 rpm's

Any good rules that you can apply???

Cold engine has more resistance, oil is thick, coolant is also more viscous (though that's only really a thing below freezing), Battery is ready to accept a charge... the throttle opens to make more power. So you used 41% more fuel on a cold engine.

AC was off with both readings, right?

 

[LazyDog]

Cold engine has more resistance, oil is thick, coolant is also more viscous (though that's only really a thing below freezing), Battery is ready to accept a charge... the throttle opens to make more power. So you used 41% more fuel on a cold engine.

AC was off with both readings, right?

Yes, the AC stuff was off!

 

[Jetronic]

well the colder it gets, the more oxygen the engine will draw in at cold idle.