MAF Calibration values data wanted.

cachaciero · Post by **cachaciero** » 18 Jun 2011, 10:42

Can anybody on here with a good 2.0 Ltr and a Lexia record values of air flow at 500 rpm intervals to 4000 revs and air temp that would be a useful table to check MAF's against.

Given that there is likely to be a bit of a spread the more submisions the better.
This would be usefull bit of info for those struggling with suspected MAF problems, values for 1.6's and 2.2's might be a good idea too.

Given enough info it should be possible to produce a graph which shows the the expected "good range" for a working MAF.

cachaciero

Post by **myglaren** » 18 Jun 2011, 10:47

A superb suggestion.

Even if I had a Lexia I don't think results from mine would be altogether useful but might add to the data.

Results from several known good cars would be useful too as a comparison.

Post by **Paul-R** » 18 Jun 2011, 11:30

myglaren wrote:Even if I had a Lexia I don't think results from mine would be altogether useful but might add to the data..

Ditto here. I rather suspect we might end up with rather more cars that aren't quite right than are gooduns!

myglaren wrote:Results from several known good cars would be useful too as a comparison.

Providing we can get them!

cachaciero · Post by **cachaciero** » 18 Jun 2011, 17:01

Even data from suspected bad uns may tell us something. IMHO MAF failures per se are not so common as are made out, the MAF is actually as components go relatively industructible (unless dowsed with gallons of salt water

. However the MAF and EGR work together, flow through the MAF will depend on EGR position.

Now it seems to me that with a cold engine the EGR should be shut for all rev ranges so a set of flow figures from a cold engine I would expect to be different from those obtained from a hot engine when the EGR should be operational. Equally there is a low rev band below which the EGR should be closed so up to this rev limit one would expect the flow to be the same hot or cold.
So in an extreme case if the two sets of values hot and cold were the same that would point to a stuck EGR valve rather than a MAF failure.
Note this is a bit speculative on my part but can't see a flaw in the logic.

cachaciero

Post by **Paul-R** » 18 Jun 2011, 22:24

I suspect that sometimes (often?) it'll be the thermistor that measures the air temperature in the the intake that's faulty. Part of the MAF assembly but not replaceable sperately.

Post by **myglaren** » 18 Jun 2011, 22:33

Paul-R wrote:I suspect that sometimes (often?) it'll be the thermistor that measures the air temperature in the the intake that's faulty. Part of the MAF assembly but not replaceable sperately.

That was the thinking on the part of the electronics guy that I gave mine to.
He thought that the platinum wires should be practical invincible.

Post by **Paul-R** » 18 Jun 2011, 23:17

This thinking was based on having to replace the thermistors in the door mirrors of both the C5 and the Xsara but have only replaced the MAF in the C5.

cachaciero · Post by **cachaciero** » 19 Jun 2011, 09:45

Actually I seem to remember reading somewhere that on the C5 the mirror sensor is used as a backup for the purposes of calculating engine inlet air temp. However where the MAF thermistor would appear to be an integral part of the whole sensor that wouldn't do much for us.

cachaciero