MAP Sensor VS Air Flow Meter

[CONRAD]

Could someone shed some light for me in regards to aftermarket engine management systems that use a MAP sensor Vs an Air Flow meter!?

Drivability for both?

What power are you limited to if running air flow meters?

Any other peculiarities or problems etc?

I was recently running a Microtech MTX-12 sequential direct fire and that used a MAP sensor.. despite having the car tuned twice by different garages of good repute the drivability in terms of starting the car and low idle were not that good – other than that it was fine and made good power. I was told that this was due to manifold vaccum pressures and the map sensor needing to get it's sh*t together on start up.. hence it would stall a lot and need multiple starts.

It's driving me up the wall.. if anyone could help, that would be mostly appreciated. Thanks

[Sydneykid]

Could someone shed some light for me in regards to aftermarket engine management systems that use a MAP sensor Vs an Air Flow meter!?

Drivability for both?

What power are you limited to if running air flow meters?

Any other peculiarities or problems etc?

I was recently running a Microtech MTX-12 sequential direct fire and that used a MAP sensor.. despite having the car tuned twice by different garages of good repute the drivability in terms of starting the car and low idle were not that good – other than that it was fine and made good power. I was told that this was due to manifold vaccum pressures and the map sensor needing to get it's sh*t together on start up.. hence it would stall a lot and need multiple starts.

It's driving me up the wall.. if anyone could help, that would be mostly appreciated. Thanks

Hi Conrad, I have seen 1,100+ ps on a pair of Q45 AFM's (90 mm), I don't believe there is a power limit. You simply use bigger AFM's, I have seen 100+ mm AFM's, a pair of those would be good for 1400+ ps.

An AFM measures the airflow going into the engine. A MAP sensors measures pressure and the ECU works out the airlfow using throttle position and rpm. So a MAP sensor driven ECU can never be as accurate at finely measuring ariflow as an AFM driven ECU. This is most noticeable at low rpms, cold start, cold run, stop start, traffic, air con on, power steer, electrical load etc etc. A MAP sensor driven ECU can be tuned to give as much max power, but it is so much harder to get the car to run "nice". Sometimes it is simply not possible, this is most noticeable in GTR's as they have multiple throttle bodies. It is almost impossible to get a decent/accurate/consistent pressure signal to feed the MAP sensor.

My recommendation for all road/combo cars is the Power FC, GTR's make good power wit them and run as "nice" as with the standard ECU. The car that makes 1100 ps with the AFM's runs a Power FC (BTW, it does 8's at ~165 mph).

Hope that helps:cheers:

[R31Nismoid]

your not limited to power by AFM's at all.

Using a Z32 AFM & a PFC will easily net you 300rwkw with no problems if you got everything else to go with it

[R31Nismoid]

qhoops... you got a GTR, u can get Nismo items with are bigger than stock, they work well

[CONRAD]

Cheers thank you for that, I hate that feeling of hearing a thousand different versions of a story by people less in the know.. ok that cements it for me. appreciated.

My microtech died so I'm going to have to purchase wiring loom, 2 airflow meters + plugs, then get it installed and tuned.

To keep cost down as this aint going to be cheap.. do I have to fork out $300 each for Z32 AFM's or can I use the RB20/RB25 AFM's? Are there any blatant advantages?

[Blk33]

I have been running a R33 Wolf 3D plug and play for the last 6 months.

It uses an internal MAP sensor or can be configured for an air flow sensor.

I chose the MAP.

Developing power on the dyno was easy and is repeatable and reliable.

As the SK says the MAPs do not meter small levels of RPM as well as the air flow sensor.

In fact I have had a ball over the last 5 months setting the tuning as best as possible at idle and with engine load such as air conditioning and lights etc.

It is good now but not as good as factory ECU.

I have cold starts and warm ups as good as factory ECU, but has taken many hours.

Cheers

Rob

[dangerous_daveo]

So what other ECUs use/can use AFMs other than PFC and would seem the wolf 3D V4???

[MonstaS4]

I'm using a Haltech E11 on my RB30DET. It can use an AFM or a MAP sensor, the latter can be calibrated to suit any brand through the software. I'm running with the MAP and cold starts, idle control, light loads are all excellent. Not a plug-in like the wolf though.

[GTR-Ben]

To keep cost down as this aint going to be cheap.. do I have to fork out $300 each for Z32 AFM's or can I use the RB20/RB25 AFM's? Are there any blatant advantages?

Well I have seen 400kw with RB26 AFM's.. we then upgraded to RB20/25 AFM's.

You can push the stock AFM's past what they are recommended to do.

[pitchd]

z32s are good for 450hp... rb26 are around 350hp each arent they?

if youre picky - and want to run a pfc with a map sensor... HKS VPC unit is your friend

- adz

[Cubes]

CONRAD,

I notice you are in Adelaide?

Who's been doing the work on the car?

Have you had Tim Possingham (Previous RPM Owner & Microtech Buff) have a look at it?

Shaun @ Boostworx also has had good experience with the microtech.