I am pretty sure the 2.5L uses a maf, a quick google search confirmed. Airflow is much more important to be known on gasoline powered vehicle.So I think if we could get the answer to why some of the OEMs don't use them and some do, we'd have the answer to why the tuners do or do not. The 2.5L 5cyl VAG engines in the current Golf/Jetta/Beetle/Passat don't have a MAF, they seem to run fine. But the VR6, the 2.0L non-turbo engine, all the turbo engines, as well as all the TDIs, do.
Also, as far as MAFs being used for EGR checking: that may be true in some cases, however there are other methods used to verify EGR flow. Temperature sensors post-EGR valve, delta pressure feedback (DPFE) sensors, and even a MAP (on non turbos) can be used. Heck, GM used to use the oxygen sensor signal to check EGR operation. Plus, many engines that have a MAF, don't even have EGR valves
The feds came up with 2 requirements:If a MAF is totally not necessary, then why do so many (the vast majority) of automakers use them?
Emphasis mine. On highway was the first to get the emissions regulation. At that time a MAF sensor met all of the requirements. And while 200k miles is plenty long in the on highway world under 10k GVWR when you're talking about running a diesel 24/7 for years it isn't. Which is why a lot of the other manufacturers didn't go with them.Every single one of the road-going diesel engines under 10k GVWR use a MAF sensor.
Who makes the MAF?Could this be a conspiracy for Bosch to sell more MAFs?
Emissions are HP based and they do have them just not in America.Keep in mind, Caterpillar does not [yet] need to meet the emissions requirements that Volkswagen does, since they are not building anything that small that is roadgoing.
This would be for offroad use only. Obviously. Like everyone else in this subforum.So to that end, it would seem a MAF is a very integral part of an EPA-compliant emissions friendly engine management system.
I thought that the MAF only reads so high and many turbo upgrades can pull more air than what they can read?
A VE Map -- Which is made... how? using a MAF maybe?A VE map.
Try big changes in altitude.i haven't really noticed any difference with the change of seasons with my maf-less tunes...
ROFL. so that's the secret reason!hey man that's great, glad to hear it. Good for you.
the OP wanted to know why people were still using MAF-based tunes, and I gave my opinion as to why maf-based tunes were still being used.
Summary: Because it still works, that's why. And... it's there.
Of course. A head of time during calibration/tuning. You tune your VE map during steady state conditions at which pointA VE Map -- Which is made... how? using a MAF maybe?
All the more reason to not use a MAF.But... We are hot rodding.
Which is why you remap it in a few spots and fill it out.Not keeping things stock. This changes VE. Which throws all the density vs pressure assumptions out the window.
A 'higher standard' that depends on sensor that is far before the intake and possibly ahead of the entire air system?We add non-stock turbos, injectors, cams, intercoolers, exhausts, delete egr, etc etc etc, and now what is VE? I guess we can assume "it's pretty close still". That may be passable enough for some, but I like to work to a higher standard.
Why do it for ALL of them? A few hours of data collection and you can be done with it.You are going to measure data and calculate VE maps for all of them?
Throttle is used for the low pressure EGR. If you're doing high performance off road tuning you eliminate EGR.not to mention any throttle on the inlet like the PDs have.
You're not measuring airflow directly. You're measuring air flow before the turbo before the intercooler, before all the piping. Pressure and Temperature are measured directly before the intake. Not "some random point". I've been thinking of turning my EGR blockoff plate into a pressure and temperature sensor point.My point is, maybe it's more expedient as hot rodders who care about smoke, for us to measure airflow directly than to suppose or assume based on a single pressure measurement at some random point in this multi-stage system.
Exactly. Measure the temperature and pressure of the manifold.Cut out the middleman and just measure it directly.
Which is why every diesel manufacturer out there uses MAFs... oh wait. They don't.Maybe we are better off using the best available tools at our disposal, if we want the best result.
IMAP needs to be measured in absolute pressure. It's the only way you can properly do the equations.Try big changes in altitude.
So does a MAF-less tune. Unless you want to remove it for simplicity.Summary: Because it still works, that's why. And... it's there.
Sounds more like a fuel temp compensation issue.is that why I've often had to tweak the IQ winter vs. summer?
Dont go down this road, more power doesn't always imply a better tune or more refinement.What was the largest engine you've tuned with no MAF? How many HP did it put out? (ball park).
Not to mention time, and moneyDont go down this road, more power doesn't always imply a better tune or more refinement.
I'd be willing to bet that Bosch Engineers that calibrate stock OEM engines have much better tunes/calibrations on them than any aftermarket tuner. Maybe not the most powerful tho.
They have access to way better tools, engine dynos, rolling roads, proper software for real time tuning etc. I have a friend that works for Delphi doing EMS and its just wow compared to what the aftermarket tools are.