Logging Boost

[Duncan]

I need to log boost on the race car due to new regs for production cars.

I'm hoping to use the MAP sensor that runs the standard (electric) boost gauge and the data logger that came with the o2 sensor. We are only running standard boost so no higher than 12psi (which the standard sender can/does read)

Has anyone ever set up logging from a sender? How do I calibrate it? Do I just tap into the signal from the sender, log the voltage of the output and map that voltage against a known gauge? Sounds hard. Is it easiest to do on a dyno so I can match up? Any trick to check the voltage? Is the output from the standard MAP sensor linear?

Need to get this all sorted for the endurance race last weekend in October! HELP!

[Swiper the Fox]

have you seen this??

http://rdmelton.autoeducation.com/cars/stealth/boostlog.html

and this

http://www.3si.org/forum/showthread.php?t=202062

[Swiper the Fox]

you could always datalog with one of these "Nissan" ecu's

i can get ya one made if your interested

[Duncan]

hmm OK so the MAP sensor puts out an unknown voltage (not shown in the manual). And it doesn't go to the ECU as far as I can see so I need to tap the signal wire.

From there the logging software needs me to do a map of voltage v boost. eg 0v = 0psi, 5psi = 14psi (or whatever). So I guess all I need to do is identify

1/ voltage for 0 boost

2/ voltage for say 14psi boost

3/ if the voltage in between looks pretty linear.

Can't find info in the service manual about the output from the map sensor (guess gauges don't come with torubleshooting sections)

Thanks for the links Paul.

[Roy]

A few rules of thumb. You need to power the gauge and make sure there is no pressure signal to it and record the voltage. That will be 0. Most gauges are 0-5V. Do you know what the max singal of the std gauge is?

A much easier way to go about it is just buy an aftermarket map sensor for $120, that way you know the scaling and range.

[Duncan]

what on earth is that ECU?

looks like there are calibration maps for the GM 2bar and 3bar map sensors that come with the data logger (TEWBLOG). Might look into what they are worth but would rather get the standard sender working instead

[Duncan]

Roy, easy...and no. But I guess I can get a fixed boost level on the dyno and record the voltage....just sounds a bit inaccurate for me.

Know any online MAP sellers (and whether they provide calibration scales to make life easy for me)?

[Duncan]

ahh now we are talking

"Well I know that with TEWBLLOG you can make Interpolation(?) tables

for any sensor. What you do is you make a basic Input/Output table in

the User1 "guage" and have at it with your know Ins/outs One good way

to check it would be to have the MAP sensor hooked up and powered and

connect a vac/pressure pump to it and go to specific situations. Both

in vac and boost...do 40in of merc, 30in of merc, 20", 10", 5",

0(atmospheric pressure) then 1PSI, 2psi, etc and at each interval you

note the voltage that is reading and then plot them into your

interpolation table for User1(which ever you use for the map)"

[r33_racer]

That is a standard genuine nissan ecu duncan. We have one also in our circuit car. Best standard nissan sm4 going around at the moment

[Duncan]

rofl I've only just splurged on a PFC....no SM4 for me yet!

There are 3 user inputs to the data logger so I'll go MAP sensor (boost), lat and long G sensors, as well as RPM. Should be interesting

[Swiper the Fox]

That is a standard genuine nissan ecu duncan. We have one also in our circuit car. Best standard nissan sm4 going around at the moment

Yes...correct. The ECU i posted Dunc's is our new Autronic SM4 cleverly disguised as a STD Nissan ECU...now thats one for the scruitneers to find eh!