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Old 09-24-2022, 06:25 AM   #1
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MAF value off a bit

The car is 2001 Boxster with 2.7 and manual transmission.

I have done some reading on forums regarding the MAF values, but would like to get confirmation to my assumption on the MAF values.

The first image shows MAF value at the idle 690 rpm to be 10kg/h.
Second image shows the MAF value at the 2285 rpm to be 30kg/h.

If I have correct information, the MAF value on my car at the idle should be approx 15kg/h with +/- 2 variation based on the EVAP situation.

Does this mean that there is an air leak or does this signify something else?
Thanks for all help on this question.





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Last edited by pilot4fn; 09-24-2022 at 12:39 PM.
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Old 09-25-2022, 06:01 AM   #2
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you would need more information such as.
Fuel trims compared to MAF values.
Throttle position compared to MAF values.
How the engine runs at idle.
How the engine runs at 1800-2500 RPM vrs idle.
O2 sensor signal at idle and midrange.

To make an assumption based on a single data point is not good diagnostics.

You could have those MAF values for many reasons.
Like aging sensor
Dirty sensor
Dirty air filter

If you think you have a vacuum leak there are other ways to determine that.
Like using a vacuum gauge to do a vacuum test.
A smoke test
How the engine idles vrs how it runs at 1800-2500 RPM

Last edited by blue62; 09-25-2022 at 06:04 AM.
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Old 09-25-2022, 11:18 AM   #3
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Quote:
Originally Posted by blue62 View Post
you would need more information such as.
Fuel trims compared to MAF values.
Throttle position compared to MAF values.
How the engine runs at idle.
How the engine runs at 1800-2500 RPM vrs idle.
O2 sensor signal at idle and midrange.

To make an assumption based on a single data point is not good diagnostics.

You could have those MAF values for many reasons.
Like aging sensor
Dirty sensor
Dirty air filter

If you think you have a vacuum leak there are other ways to determine that.
Like using a vacuum gauge to do a vacuum test.
A smoke test
How the engine idles vrs how it runs at 1800-2500 RPM
Thanks blue62 for a good info

The car runs real well thru out the rpm range - also at the track.
Reason for this original question is that I'm trying to investigate (and budget) the upcoming winter maintenace work needed (all chain ramps, RMS, IMSB, flywheel, clutch, chain tensioners, etc) or if there is something bigger issues for larger teardown.

I'll continue investigating with more detailed approach.
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Old 09-25-2022, 12:37 PM   #4
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Quote:
Originally Posted by pilot4fn View Post
Thanks blue62 for a good info

The car runs real well thru out the rpm range - also at the track.
Reason for this original question is that I'm trying to investigate (and budget) the upcoming winter maintenace work needed (all chain ramps, RMS, IMSB, flywheel, clutch, chain tensioners, etc) or if there is something bigger issues for larger teardown.

I'll continue investigating with more detailed approach.
A few dyno runs would tell you lots about how the engine is performing.
if it had performance issues dyno runs can help you pin them down.

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