I was told the Bosch MAFs have a tendency to spike lean by a few people. Other's disagree on the reasoning behind it. I know on the B5 S4, the change to Hitachi is due to reliability issues. TIA

 

The switch would be for reliability and for sensitivity. If I understand it correctly, the
signals from the hitachi are reliable and cover a wider range of air flows with a more
accurate signal, allowing a chip tuner to make a more accurate map/program. Experts
will doubtless correct me and/or expand on this...
Joe

 

That's pretty much what I was told. I was told that this lack of resolution is what causes lean conditions to go un-corrected in proper time.

 

MAF have designed in flow ranges. If you're an OEM making say a 996TT and it's rated at say 400HP why would you spec a part that's going to meter 600HP? Meters that can do 600HP have lower resolution on the bottom end - right where driveability and emissions can be effected. You also have to look at granularity - if a meter can measure 0-600HP and another meter can measure 0-400HP which do you think is going to be more sensitive at 200HP? Last but nto least - flow as in CFM. Bigger meters flow more air and are also generally rated for higher HP. The MAF on a Ford Cobra flows more air than say one on a Ford Focus - and meters over a larger range too. On the 996tt meters are getting maxed out which can be dangerous if you go too far past the rated metering range, so folks sometimes upgrade. Doing a blow through vs a draw through can also allow you to clean up intake piping - the draw through intake piping on these cars is a bit convoluted which hurts flow too.

 

Where can I order it?

 

This is a fairly accurate description of why we are testing 3 different solutions at the moment. Although we haven't seen to many issues with the stock maf, in the STOCK airbox, around 700 crank hps or so.

The most promising is a factory style drop in maf that will read nearly double what the stock maf will, in the same size tube.

 

AFAIK it was a solution to an intake that was blowing MAFs...I won't point fingers...LOL

 

For cars making 700HP and up, will save you $$$

 

Lol...

 

I have a stock MAF sensor. Recently I've blown a compressor hose off on 2 occasions and both times it has ruined the MAF sensor. I've blown hoses off in the past and it didn't happen then. Why would it be doing it now and not before? I ran the same sensor for 2 years. Would a different type of sensor be less prone to this problem?

 

Are you running stock hoses? If not and you're blowing them off that regularly thats the first thing I'd tackle - get ahold of Alex at Sharkwerks or Dan at Vivid, they both have good prices on the hose kits right now. If you've already done that upgrade how much power are you making? - PM me if you want so we don't Hijack the thread.

 

Not to hijack this thread but I wish I understood this better.
The original question of what the dollar buys with a Hitachi caught my eye.

I understand that a tuner setting up his program must work with a variety parameters including data that the selected MAF will generate. The 'data' in the case of a MAF is the continual metering of the current required to keep that foil element at a constant temp as air flow changes.....which in turn helps the ECU set up correct injector timing.....at least this is how I've always understood it.

So, do all MAFs meter differently? (i.e. require different current? when all else is the same).

If different....then they must have published specs that a tuner works with?...surely it's not a trial & error thing.
But if they are not all different (i.e. different current)......then if an OE MAF 'works' in a car (no CEs and performance OK), would a Hitachi also 'work'?

TIA

 

Gregg, I can't speak for ALL, but I assume there is a difference in the metering between the Hitachi MAF and the Bosch MAF. If there wasn't there would be no reason to switch. The ECU parameters need to be modified. I am sure the tuners have played around with it enough to modify the ECU appropriately (as long as you're not the beta tester...LOL)

 

So we're probably saying that......idling or at a specific throttle.....that one brand would meter a different current level than another.

This would be asside from other difs like higher capacity....ability to handle more flow top-end w/out burning up, or....more accuracy......from better or different engineering.

 

From my understanding (and keeping way simple) of the way thin film air flow sensors work, the signal sent to the ECU is a function of the change in temperature from one side (air flow side) to the other. The signal is sent as a voltage signal. Now if the airflow is violent or unusual (as may be produced by intake changes or increased hp) this can have an unpredictable effect on the sensor. Airflow fluctuating too quickly can create voltage spikes which can 1. fry the sensor and 2. send the wrong signal. Obviously sensors can be developed robust to the changes in airflow to accommodate changes you've made to the system, but they send different voltage signals and therefore the ECU needs to be manipulated to handle the new signals.