Basically, what's the deal with our mass air sensors?

Ok, after upgrading exhaust, or intake system, with whatever.. Bigger intercooler, hard pipes, 3" TBE with test pipe..

WHY DOES THE CAR RUN LEAN?

Yes, More air is being pulled through the engine, & such, but the job of the MAF is to tell the ECU that MORE AIR IS BEING PULLED THROUGH, & then the ECU should add more fuel with it...

So why the need for a re-flash? It should easily compensate for better flow with counting more air, & adding more fuel, right??

Please enlighten me.

 

It does not typically run lean with just an exhaust, but rather with an intake. The reason is that the intake disturbs the flow through the MAS and causes inaccurate readings.

-Paul

 

Excellent. Thanks for the answer.

Now, I wonder if it's typical for it to cause leanness, or a rich condition on average...

 

There is more to a flash than just air/fuel combo. It also takes out the limits set my the US version of the Evo. Its like the old days when you removed the governor from a carburator (Some of you guys won't remember that).. Boost also can be adjusted to a different limit and whole lot of other limits.

 

because your car is open loop at WOT and your ECU doesnt use feedback at that point.

 

That depends on the intake. Take, for example, a test I did on my car: if you put a less restrictive air filter in the stock airbox (or run it with no filter ... not recommended), then it will run approximately .2-.5 AFR leaner than it otherwise would.

Changing out the stock airbox to another type of intake generally needs to be tuned for, since a lot of aftermarked intakes do affect MAF readings.

l8r)

 

Actually, I believe that in this situation, it doesn't use the o2 sensor for feedback, but it DOES still use the MAF to regulate fuel input.

 

What about a drop-in panel filter like K&N? Would this disturb the MAF enough to loose power without a ECU tune? I have heard of people dropping them in and getting better results, but I feel like it slowed my car down, even having dried out the K&N and cleaning the MAF sensor with the CNC cleaner.... should I put my stock filter back in until I get my dynoflash?

 

this is good knowledge.....lol

 

The drop in filter should not disturb the air going through the MAF, just allow more to go through. I'd imagine it shouldn't hurt anything for a drop in.

 

I assume you meant CRC cleaner, right?

Also, I really doubt you could actually feel the difference in power when going from a stock filter to a HF filter. I tested it on my car and the difference was 5 whp ... all of which, I'm guessing, came from the fact that the car ran leaner with the HF filter.

l8r)


... as discussed in another thread:

https://www.evolutionm.net/forums/sh...4&page=1&pp=15

and here is a new product made by CRC industries Inc.

http://www.crcindustries.com/auto/co...x?PN=05110&S=N

Mass Air flow sensor cleaner, safe for the plastic parts too..

 

yeah I meant the CRC cleaner- just used it again and my car is running right... peak boost @3700rpm in 1st gear (~1.4 bar), ~3400rpm in 4th