Cret

I get a column on the log files from my Power FC/Datalogit that is called "MAFS Act" over near the right hand side of the file. Anyone able to confirm what this represents and what the units are for it?

I get figures pretty much anywhere between 0-20 (mostly between 1-10), but it seems that when there are values between 0-1 is where I've had issues with the car cutting out.

The problem was the car would suddenly cut out completely and then when you try to restart it fires for about a second & cuts again, and keeps doing this. Very intermittent though.

When this is happening the figures in this MAFS act column are 0 but when the car runs ok they are generally between 1-10 or thereabouts.

I cleaned the maf and it hasn't cut out yet since as I was pretty sure that was the issue, but that was only one drive since then so it might be a coincidence.

Presume this data is maf related from the description, but I can't find any reference to it in the fc edit manual so I'm not sure. Can anyone confirm?

Cheers
Jim

Cret

Bump - anyone?

Pavlo

you need to look at it with 2 decimal places, it's roughly translated as airflow. At the point of stalling airflow will be low, so it's natural.

Cret

Thanks for the reply Pavlo - much obliged

Does it represent a particular unit of volume or is it just an abitrary figure?
The reason I thought it represented a maf failure was that when viewing a log file which includes stalls, this figure drops BEFORE the idle RPM drops, which does not make sense given that if the engine is still idling the same amount of air would be flowing through.
As the signal drops almost out completely, it seems a direct consequence of this is that pretty much no fuel gets injected and the car then stalls.

When I then restart the car it fires up for a couple of seconds and cuts straight out again but all the time through that sequence of cranking, firing, running (briefly) & stopping, the output in this column remains as zero, which again makes no sense if it is showing airflow since there will have been some while the engine ran for a couple of seconds. Hope I've explained that well enough!

The other issue I have is with the knock sensor I'm using for the PFC. Previously I was just using a knockling and the sensor for that is on the oem sensor position. I've add the oem sensor back again, to a different spot between head & block, but the PFC does not register the slightest hint of knock when i hit the engine in various places with an extension bar.

The reading across the sensor is approx 550k ohms, which I think is about right, and the electrical connection seems ok to the harness so I'm not sure why nothing would get picked up. There is a good solid physical and electrical earth contact.

As far as I know in FC edit there are knock threshold settings but is there something I have to do to actually tell it to use the sensor, or anything like that?

Appreciate the help mate. The car has been off the road for a couple of years or so while I've rebuilt the engine (lack of money and new wife/new house/new baby etc) and I was just getting into mapping but a lot of info has gone out of my head now.

Cheers
Jim

Pavlo

it's pretty arbitary i think.

your maf sensor wiring is somehow dodgy, on cranking there is a fixed injector opening time set in the cranking menu, once above a set speed you switch to the main fuel map, so if the maf is unplugged it will fire and run for a seconed then cut.

you haven't disconnected the idle valve from the intake pipe have you? if you do the air drawn for idling doesn't go through the maf!

Paul

Cret

Cheers Paul. I wonder if there's a dodgy pin on the plug or something. I'll try inspecting/cleaning them.

Not disconnected anything like that but do you mean idle valve from the manifold rather than the intake pipe? Not aware of anything like that on the intake - sorry if I'm being obtuse!

Another reason I was thinking knackered maf is that while the care was off the road the intake pipe with the maf & filter were sat in my garage and were slightly grimy. It was cutting out a lot but I cleaned the maf and it's improved loads but still occasionally does it.

Another symptom was a fair bit of stuttering when I began to drive up a slight incline last night.

I have to be careful how I drive it since I'm running it in still.
Is there a definitive way of testing if it's a reliable maf sensor or a knackered one? The only test I'm aware of is to unplug it as I believe a healthy maf when unplugged makes the car stall.

Mine does this as if it's fine but the stall issue is intermittent so it might be that another time it might carry on running when unplugged. Makes it difficult to pin down the cause of the problem.
I'm sure it must be a dodgy maf but can't afford to replace it without being certain hence why I'm trying to figure it out from log files etc.