Upgrading MAP Sensor for FA R3s

hombre

Nitrous
Joined
Dec 31, 2006
Messages
1,021
IMO, any forced air inducted R3 should be running an upgraded MAP sensor.

I'm sure most (if not all) operators of FA R3s have noticed the "niggles" or "burps" in their engine when operating the throttle through the RPM range. Some kit makers have recommended disconnecting the MAP sensor to smooth out these throttle response problems. This is akin to chopping off your hand because you sprained your wrist.

The ECU uses the manifold absolute pressure (MAP) sensor to determine the absolute pressure (not the relative to atmospheric pressure) of the air inside the intake manifold and the atmosphere (barometric pressure). This information is used to determine the density of the air entering the combustion chamber in conjunction with the IAT (Intake Air Temperature) sensor, which is used to calculate the proper air/fuel mixture for the engine. This is especially important at WOT since the system is not in closed-loop at this time.

The MAP consists a silicon wafer that is thinner in the center (0.001") than around the edges (0.045"), which causes it to act as a diaphragm. The wafer is mounted with a perfect vacuum beneath the chip so that the air pressure from the other side flexes the chip. This flexing causes a change in resistance and the circuitry inside the sensor converts this to a voltage ranging from 0.02V to 4.94V when the output is pulled up towards 5V by the ECU.


1 Bar MAP Sensors are used on NA(naturally aspirated) vehicles.


2 Bar MAP Sensors are used on forced induction vehicles (Turbo & Supercharged). They can measure up to 2x the atmospheric pressure (29.4psi), so that means it can measure up to 14.7psi boost (the atmosphere is 14.7psi + 14.7psi from the turbo/supercharger).


3 Bar MAP Sensors can measure up to 44.1psi, which translates to 29.7psi boost from a Turbo/supercharger.


They all share a common pin-out, although the connector keying may be different:
Pin A -- Ground
Pin B -- Sensor output
Pin C -- +5 volts

Using a correctly rated MAP sensor for your boost application will remove the throttle burps from your FA R3. Additionally, IMO the upgraded MAP sensors are of a higher quality than the stock Triumph sensor... always a plus.

For FA R3s, upgrading the MAP sensor is as important as using larger injectors and a higher volume fuel pump. Not paying attention to these mods when going to FA induction on your R3 will result in not only a loss of power, but possibly a melted piston when running WOT for extended periods. :eek:

As discussed in another thread, good digital EGT and Wide-Band AF readouts are also recommended. :cool:
 
Last edited:

goodfellow

Turbocharged
Joined
Jun 12, 2007
Messages
745
map sensors

hombre,
thanks for the heads up,i never would have given this a second thought.


greg
 

hombre

Nitrous
Thread starter
Joined
Dec 31, 2006
Messages
1,021
I've been asked by private email which MAP sensor should be used with a turbo installation. The important thing is to match your MAP sensor to your new injectors and boost of your FA system. In the case of the TTS supercharger, the new injectors are twice the size of the stock injector, and the max boost is 14 PSI. This means the ECU will be "reading" twice the MAP of stock, and requires a 2 BAR sensor for correct fuel metering. If you plan to run a turbo that can deliver 30+ PSI boost and 300-350 RWHP, you will need an additional set of injectors (they are not made in size 3X stock) to supply that much fuel, and a 3 BAR MAP sensor (maybe even 3.5 BAR). If your turbo kit isn't supplying new, larger injectors, I seriously suggest you find another "kit" supplier.

Summit Racing has the higher boost MAP sensors here: http://store.summitracing.com/egnsearch.asp?N=700+4294849426+115+4294891681

IMO, the things that need to be done to an forced air R3 to make over 300 RWHP are legion, and are the proper subject for another thread. I look forward to discussing it with those that are interested, and the many knowledgeable speed freaks here. :D
 

hombre

Nitrous
Thread starter
Joined
Dec 31, 2006
Messages
1,021
Questions keep coming...

MSD 2 BAR map sensor part#2312



Wiring:
MSD "A" = Grd
MSD "B" = Sensor Output
MSD "C" = +5v input
 

hombre

Nitrous
Thread starter
Joined
Dec 31, 2006
Messages
1,021
While it's obvious to anyone that has actually looked at the stock R3 MAP sensor, you will need to fabricate a wiring adapter for the above sensor. Above is "GM style" and I believe stock is "Bosch style". Adapter is simple... just keep "A", "B", & "C" leads straight.

Motec makes an adapter, but it still requires M/F swap.

The R3 ECU is designed to run with an operational MAP as load sensor. Disconnecting the MAP sensor will eliminate "burps" but give less power. Replacing the MAP sensor with one of the correct range and retuning will let the ECU properly produce full power potential. :cool:
 

Pig9r

Living Legend
Joined
Mar 5, 2006
Messages
4,843
Location
Kansas City, MO USA
Hombre--Keep in mind I know nothing about forced intakes, and not much about fuel injection, or speed density, but does the MAP sensor do much beyond 7% throttle openings? Looking at the L maps in Tuneboy, which are for throttle openings of 7% and less, it uses MAP and RPM to determine fueling. The L tables, which are 11% throttle openings and higher, use throttle position and RPMs. So does it still use the MAP sensor at higher throttle openings?

I wish Triumph would have used a MAF sensor.

Also I came across this site and thought you might find it of interest, a DIY ECU.

http://www.bgsoflex.com/megasquirt.html
 

hombre

Nitrous
Thread starter
Joined
Dec 31, 2006
Messages
1,021
You're right, Brian, although I thought the dividing point between "L" and "Main" tables was 6% throttle. No matter, because this dividing point is where the problem occurs with FA R3s. The stock MAP sensor works well inform the ECU of the load on a NA bike, but with FA induction, it reaches it's limit of 1 bar at 5-6% throttle (maybe sooner on turbos). When the stock MAP sensor maxes out at 5v, the ECU goes to full rich metering... from something around 13 A/F to 10 A/F. This is the "burp" that is experienced by FA riders with stock MAP sensors. You can open the throttle further, and get "beyond the burp"... but you're defeating the purpose and capabilities of the ECU (precise fuel control). You may as well just go back to carbs if you're going to disconnect the MAP sensor.

Installing a MAP sensor with a 2 BAR range (or more if you've got more boost), and then retuning the ECU to match the new voltage scale (0-5v), allows the ECU to do it's job... more precise fuel control. :)

MegaSquirt is obviously aware of this problem:

"MegaSquirt® features an on-board Manifold Absolute Pressure (MAP) sensor (Motorola MPX4115). Having the MAP sensor on-board simplifies installation (one just runs a vacuum line to the ECU) and keeps the measurement signal clean, which is very important since the MAP signal is the most critical to proper fuel control. There are other Motorola MPX-series MAP sensors with expanded scales to handle turbo and supercharger applications, like the MPX4250A (this sensor handles 3 to 36 psi, or 20 to 250 KPa) - one can swap this sensor in with hardware change. The MAP sensor is additionally used to obtain the barometric pressure during engine startup, in order to determine a barometric pressure correction factor (explained below)."
 

Joker

Turbocharged
Joined
Feb 18, 2007
Messages
625
Location
UK
Hombre,
Do you know if Richard has taken care of all this on his bike? Sorry to bother you but he's away at the moment and I'll have forgotten the question by the time he gets back.
Thanks
 

hombre

Nitrous
Thread starter
Joined
Dec 31, 2006
Messages
1,021
Hombre,
Do you know if Richard has taken care of all this on his bike? Sorry to bother you but he's away at the moment and I'll have forgotten the question by the time he gets back.
Thanks

No bother, Joker. Your R3 (formerly Richard's) is tuned with the stock MAP sensor disconnected. I informed Richard of the MAP sensor upgrade, and he asked me how to install and tune it... so I think he can do this for you when he returns. You do have the larger K&N filter, and I know you'll like (and need) the Lock-Up clutch.
 

hombre

Nitrous
Thread starter
Joined
Dec 31, 2006
Messages
1,021
Ha! It's really so simple to make the 2 bar MAP sensor work perfectly... unless your forum's overrun by ozholes. ;) The voltage scalar to the ECU needs to be changed, either internally or externally to the ECU. Whether 1 bar, 2 bar, or 3 bar, all MAP sensors use the same 0 - 5 volt output (see clue in chart above). Since I couldn't get into TuneBoy to facilitate a change to the ECU scalar, I wired a simple DFR (Digital Fuel Adjuster) between the 2 bar sensor and the ECU. All this does is allow me to reset the volatge scalar going to the ECU.



The DFA is an extremely simple tool. By way of a jumper setting, it is calibrated for a particular input DC voltage range, eg. 0-5V. It then takes an input voltage, applies a programmable "plus or minus" adjustment to it, and produces an output voltage. It's important to note that there is only one input (MAP voltage) being intercepted. There is no separate "RPM" input. The DFA simply carves up the input voltage into 128 "points", and applies a programmable lookup table of adjustment values. For an input ranging from 0V to 5V, "Point 1" would be 0V, and "Point #128" would be 5V. At each of these points, the voltage can be increased or decreased by a "delta" value. The programming is performed using a push-button hand controller with an LCD display.



You can see that the DFA is not an RPM-based voltage interceptor in any sense. It cannot adjust input voltage based on engine rpm... unless the input voltage itself is directly proportional to engine revs. This explains why the DFA is so useful as a MAP sensor interceptor. The MAP sensor produces a simple DC voltage that is proportional to airspeed. Lower rpm means lower airspeed, which means an output voltage at one end of the range. As rpm increases, so does airspeed, so the output voltage changes to reflect the increased engine load.

It's nice to be on an R3 forum with Gentlemen, where these innovations are appreciated! :D
 

Similar threads

Top
AdBlock Detected

We get it, advertisements are annoying!

Ad-blocking software does a great job at blocking ads, but it also blocks some useful and important features of R3Owners. For the best possible site experience please take a moment to disable your AdBlocker for R3Owners.Net.

I've Disabled AdBlock