MAF sensor error

[TransAmDan]

The MAF sensor measures air in grams per second. It sits after the air filter and before the throttle body. It is made up of some wires across the air flow, with that is calculated the air flow.

The faster your engine revs the more air your engine requires.

That being said while doing some loud pedal runs I have noticed some bad readings from the MAF.

Why does this look bad? Well where the cursor is, it appears to be working okay MAF reading 301g/s of air @ 5843RPM, but to the right of that Revs keep rising and MAF value drops off. Foot still too the floor indicated by throttle position. the MAP sensor (manifold air pressure) is reading correct and still high at the same point the throttle position is.

Q. Was this just a freak occurrence?
A. No, it done the same in 3rd gear

Am I pegged out of the MAF capacity? no, it is capable of 500g/s.

Is the MAF dirty, well possible, but why drop off at that point?

Done it again in 2nd gear at a lower RPM.

I can unplug the MAF and run in a mode called Speed Density. It will use the MAP sensor to meter the air.

I can buy a new MAF, but would like to go a larger diameter, but while doing that need a larger air box, larger throttle body and larger intake, so that is a plan down the road a bit. So prefer to hold off on the MAF replacement for as long as possibe. So running without the MAF may be best.

You may wonder why the engine goes rich when the MAF readings drop off, well that is a safety thing I luckily had in there, as the car was going to command 14.6AFR as it doesn't think i was putting the engine under load.

 

[AmericanThunder]

Nothing wrong with MAP, the hemi’s only use MAP.
Why do you want to upgrade to a larger MAF? If you aren’t maxing out the current setup there is no gain so why?

 

[TransAmDan]

Some cars use TPS and RPM. I think I will run without MAF for a while. It will save buying a new one.
The reason I was thinking bigger wasn't to measure more flow, it was purely larger diameter.

I have a Fast intake manifold, ported to match the aftermarket head inlets. This has a 78mn throttle body attached to it, stock size, I have polished it internally. Then a blue pipe to the MAF, this is an aftermarket MAF housing with stock MAF sensor, so still stock size, then to an aftermarket air lid, still stock diameter.
The car is using a lot more air than stock, if I can make it flow more freely then the engine should like it. I can get a larger intake, more torque which will complement the stroker, that intake has a 103mm throttle body, so as that is really upgrading from a 3inch bore to 4inch then best to keep it that size for the entire airflow route.
Many people run without MAF and I have done for a few months in the past, was checking through many logs even back to 2005 and 2006 when I first got the kit.

 

[AmericanThunder]

If you aren’t maxing the current setup the engine won’t notice any difference.
But we all like bolting on new shiny bits! ?

 

[TransAmDan]

The current setup is restricting the airflow. My limiting factor is getting air into the engine, I can deliver more fuel, but being NA I have to rely on air being sucked in.
Even on a stock engine changing the intake can net 20hp, that is the intake I have. Engine is around 10% bigger now.
I'm trying to justify shiny bits. It will be a while of yet anyway.

 

[AmericanThunder]

The current setup is restricting the airflow. My limiting factor is getting air into the engine, I can deliver more fuel, but being NA I have to rely on air being sucked in.

Oh, then I’m misunderstanding your first post. You said you were peaking at 300g/s whilst the MAF is capable of 500g/s which is only 60% capacity?
Doesn’t matter, was just thinking Fays Watts Link first!! ?

 

[TransAmDan]

Yeah Watts link is still on the list, no point having the power if I can't put it down.

 

[TransAmDan]

MAF sensor is now unplugged. Ran the car on tick over in the garage to check its still reading Cylinder Air Mass, as I have a log from a long long time ago where with the MAF unplugged and the air mass wasn't calculated. Without Cylinder airmass then the spark advance would be the same no matter the load, just dependant on the RPM. So at least with this test, I'm happy the spark table will be addressed correctly.

The values in the cells is the commanded spark advance. This was on start up, these values will be slightly different once warmed up.

Even if everything works out perfect without the MAF, i still want a larger intake and throttle body.