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Old 11-16-2021, 06:01 AM   #16
DrRobin
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Join Date: Sep 2021
Location: UK
Posts: 38
[QUOTE=blue62;643432]
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Originally Posted by DrRobin View Post

It does not happen often but they (MAF sensors) can meet those voltage specs. and still be faulty.

If you try cleaning the MAF only use a MAF cleaning spray. Don't touch any part except the plastic housing and air dry only. They are touchy little devils. Cleaning only works about 50% of the time.
Also if your running anything other then a stock air filter, non stock air filters are hard on MAF sensors.
I am running on a stock air filter, it was just changed, but didn't make any real difference.

I measured my MAF voltage today, in fact I measured it several times as the engine warmed up at idle.

Ignition on, engine off MAF = 1.008V

Engine on, fully warm MAF = 1.400V, RPM = 793, MAF 4.2g/s (15Kg/Hr)
The short term fuel trims on both banks were around -4%, slightly more negative on Bank 1.

I took readings as it warmed up, once the fast idle had stopped, as follows:

MAF=1.490V, RPM=857, MAF=5.2g/s
MAF=1.475V, RPM=836, MAF=5.1g/s
MAF=1.450V, RPM=806, MAF=5.0g/s

These are lower air flow than I saw a couple of days ago (6.5g/s at idle), not sure how much it changes with temperature, but it is a lot colder here today.

I appear to be just in spec (1.2 - 1.5V at idle) and 13 - 15Kg/Hr, but at the high end and given that my fuel trim still shows the engine as running rich should I still suspect the MAF?

Unfortunately my 5 point security Torx didn't turn up today, so I haven't had chance to remove the MAF for checking/cleaning, perhaps tomorrow it will be here.

I fully charged the battery yesterday between the two tests, with it sitting on the drive, opening and closing the hood and not driving the battery was a little low, not enough to cause any starting problems. Not sure if the battery charge level from 15% to 95% would make any difference?

Robin
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