MAF Sensor piping

[dilmah]

Hi all

I have recently upgraded my intake piping from stock (2" or 2.5" not too sure) to 3" stainless. I have managed to bolt the MAF sensor back in using 4mm nutserts, it was pretty straight forward to do really.

I have been told by a mate that by changing the intake piping the MAF sensor will be out as it is calibrated for a 2" or 2.5" piping? Some basic research (some 3 hrs) and I have only just scratched the surface on MAF tables, voltage and volumetric flow rates.

I need to know from people who have done similar mods if this has affected their tuning. From my research the Nav will just run leaner as it will be getting more air than its reading. I don't believe it is running a boost sensor or MAP sensor, I still need to look at the engine schematics from the workshop manual.

Any help would be great

Thanks

Dilmah

 

[Old.Tony]

From what I know of fluid dynamics, your friend is right. The sensor is calibrated for the amount of air that will pass through the smaller pipe, which for a given volume per minute, will move at a particular rate, cooling the wire within the MAFS at a specific rate for the ambient temperature and speed of air movement.

A larger pipe would allow the same volume of air to move in at a lower velocity. This means the wire within the MAFS isn't cooled as much and the ECU will assume that there's less air moving in. This may be accompanied by a change in fuel map (to reduce fuel input) and may result in less power.

It's partly because of the way the MAFS is designed: it needs a certain amount of air flowing over it at a certain temperature in order to change the resistance of the wire by a certain amount. Slowing the airflow will change that calibration.

 

[dilmah]

Looks like Ill have to change the MAF files, should be achievable with a bit of remapping

 

[Rumpig]

Search for " jaycar digital voltage modifier" or something similar on the Patrol forum, it's what they use to stop limp mode for the maf over reading.

 

[dilmah]

Yeah I had a look at that, may be the go in the short term

 

[dilmah]

Only noticeable difference is a lack of low down power, once it hits 1400rpm the turbo is at 5psi and spooling. Id say that it is deffs slower off the mark though

 

[gazza414]

Why would you need to modify the MAF files ?...it measures mass flow dynamically thru a temp drop across a resistor.

Really dont understand your logic .

 

[Old.Tony]

The temperature drop is precisely dependent on the rate of flow of air across that resistor (hot wire) - the exact velocity of air molecules hitting it.

If you make the pipe larger, you get the same amount of air moving at a slower velocity. The slower velocity won't cool the wire as much, altering the reading.

 

[dilmah]

Hopefully if I add a little more fuel down low with the unichip it will solve the issue. I ordered an AFR probe the other day so it should really help with tuning

 

[camo.b]

Hopefully if I add a little more fuel down low with the unichip it will solve the issue. I ordered an AFR probe the other day so it should really help with tuning

Which one did you end up ordering?

 

[dilmah]

http://www.innovatemotorsports.com/products/MTXL.php
Just be careful what you buy, you need a sensor that works between 14 - 25 AFR, the auto meter one only goes to 20 which isn't high enough for a Diesel

 

[dilmah]

Well I bought a digital voltage modifier from Jaycar. They didn't have any in stock so it has to come from over east, should see it next Tuesday. Im gonna have a play with this and will post my results in this thread. My main aim is to increase throttle response through manipulation the MAF voltage. I want to see more fuel in the 800 - 1600rpm rev range to help spool the turbo quicker.

 

[camo.b]

http://www.innovatemotorsports.com/products/MTXL.php
Just be careful what you buy, you need a sensor that works between 14 - 25 AFR, the auto meter one only goes to 20 which isn't high enough for a Diesel

Yep that the one i was looking at also..apart from self build afm kits it seems to be the only one capable of use on a diesel.

 

[camo.b]

The autometer one seems a bit cheap too...no logging output and a basic display..

 

[dilmah]

Yer im gonna buy one when I fit the TT, for $210 its pretty cheap. Im also gonna run some more temp sensors in the intake piping to calculate efficiencies of the W2A, another boost gauge for the 2nd turbo, a water temp gauge, oil pressure and oil temp and a transmission temp. I will have to make up a custom dash cluster soon. Ill have something like 15 gauges!

 

[camo.b]

Will definatly need pics of that

 

[camo.b]

Where have u got the temp probes now? Ive got just after the turbo...in the alloy bend and in the intake manifold neck

 

[dilmah]

One is about 3" post turbo, the other is next to the EGR blank so near the top of the intake manifold so similar place to yours. I'm going to run the second boost gauge in the inlet manifold to see if I have any losses in the intercooler setup. Ill be happy with anything less than 2psi.

As for gauge setup I'm going to run all Auberins digital gauges (same as the current W2A ones) with their respective senders. They are good quality, easy to set up and well priced. Its easy to drill and tap or weld the bungs in. They will be displayed along the top of the dash (Navi side) where the airbag is (that will have to go) so they can monitor them and I focus on driving. Ill get a piece of sheet metal laser cut so the gauges fit in nice and snug.

 

[dilmah]

Picked up the voltage modifier today from Jaycar, ended up being $150 with a 25 pin female to female lead and the hand controller was $60. I got my mate to put the board and components together as he is an electrical engineer. They both come as kits and you have to solder all of the components in. Nav is in the shop this week getting sliders so it will be a few weeks before I have time to play around with this.

I ended up winding the boost up even more, it has slightly improved turbo response. I just start backing off the gas when it goes over 20psi. It was at 23psi not it can spike at over 26psi and hold 25 on full noise

 

[dilmah]

Well the voltage modifier and hand controller have been put together but I haven't installed it yet, got a trip and comp prep to do so Ill have a look at it in about 3 weeks