I've been doing some logging of WOT runs with the UTEC and I have noticed I NEVER acheive a load point of 90% or greater. Also my maximum repeatable MAF frequency is about 1630. I have had one reading of 1700, and another of 1706, but even they registered a load point of 70% and 10% respectively ( can anyone explain this ? Like it has to be averaged over time etc ? )

I read in another post someone had a similar situation where they never got 100% load point and so they were advised to change the MAX MAF freq setting to line up with their peak MAF reading. So in my case I would change it from 17 to 16.

I will try this, but I was wondering if there is any down side to it ??

I am assuming TurboXS set the Max MAF at 17 for some reason ( like their car gave a max MAF of > 1700 ), anyone know if there is any better logic / reason behind that value ???

Also out of curiosity I am wondering what everyone's Max MAF freqs are. Anyone wanting to contribute please list your maximum REPEATABLE MAF frequency and mods you have on the car. I'll start things off with :

Max Repeatable MAF : 1600 - 1630
Mods : K&N Air filter

 

Depending on your mods, your MAF value will drop.. The bigger pipes, MAF pipe, anything that increases volume lowers the MAF reading.. I had the same issue..

Whats interesting the max possible MAF value that you can get on one of these sensors is 3000hz.. Don't expect to ever see that.. I have mine set to 15 but I recently made some other changes and its now around 1600 repeatable..

 

anyone else want to contribute ?

 

BTW The stock airbox will go as high as 1800 repeatable, with a freeflowing filter, it will be lower, 1600 or so repeatable doesn't sound "Wrong".. but thats part of tuning, you have to tailor your tools to work with your setup. Again, I set mine to 15..

This was a bump post for you.. I don't think too many people saw this post..

 

MalibuJack,


thanks for the additional info.

Also when I said K&N I should have said "drop in" K&N so I am basically using the stock airbox.

Thinking my MAF readings were a bit low I decided to put back in my ( a little ) dirty stock air filter and do a few WOT runs. As with the K&N I only got low 1600 readings. But what was a little bit more worrying is that with the stock filter I now got knock !

Looking at the WB O2 readings I could see why - the AF's were at times above 12 and sometimes even 13 ! Putting the K&N drop in back in, the knock went away and AF's were back to normal.

I am a little puzzled as to why the AF would run lean with a restricted filter. After all surely less air means you're still getting the amount of fuel ( when in open loop ) and so I think it should run even richer ???
The only explanation I can think of is that the MAF reading is WAY OFF ( that is it's measured less air than there actually is ) and so not enough fuel is added and so I got knock.
Any theories anyone ???

 

Well, the only theory that I can think of is (if you can get the MAF reading) that your probably right, the low airflow due to a really restricted filter may have either read very low and the engine ran real lean (with real aggressive timing) or ran with really high MAF reading and got fuel cut (fuel cut does register as a knock event on the UTEC since its an abrupt shut-down of the system which makes noise) but fuel cut is not gradual.. its abrupt and disturbing to experience. A misfire would register being richer than normal, and fuel cut would register as lean, but of course, you'd know it if you got it..

 

and although I could be wrong, the load site is calculated by several things not just MAF reading, but sustained maf reading (it stays over a certain point for a certain time) I think throttle position also plays a factor though I don't recall reading anywhere whether or not this is true.