So i finally installed my Greddy pressure (MAP) sensor and I could not verify my data, so I can accurately change my fueling & timing tables. Below is a copy of the graphs I developed with equations along with a set from MugenRioS2K.







Also here is a data log and the Greddy sensor is reading very erratically. I would like to assume it is the sensor but I fear that something else is going on. The vacuum line is running from the sensor to the FPR with no other items tied into the line. I fear that I have a bad valve, waste gate, or possible the BOV.

 

Look at your time scale and pressure scaling


The Greddy pressure sensor and for that madder the stock pressure sensor if relocated off of the Throttle body) will see fluxuations in the intake manifold.


What the P. sensor is seeing is the acoustically induced pressure changes.


There is a bit of reversion in the intake manifold that helps push air into the next cylinder in the firing order. Think of it like an exhaust manifold that is designed to help scavenge the next cylinder due to negative pressure in the manifold when the exhaust valve opens.

Same theory/process but on the intake side.

 

Yes, but the stock map is the light blue and the Greddy is the dark blue, as you can see the Greddy is much more erratic overlaid on the factory. I think I will have to put a resistor and capacitor inline to smooth this out.

 

i can't see the maps since work blocks the images, but Mark's got this =P I was never a tuner...so my knowledge with this is very limited.

 

Rapid changes in the pressure readings are normal.

However I just looked at one of my dat logs and your pressure fluxuations on the Greddy P. Sensor do not look normal.




Dsddcd make sure your scaling for both pressure sensors is exactly the same.

If they are set differently you can get graphs that do not correlate to each other.


If they are the same then it looks like something wrong.

Try moving the Greddy pressure sensor source to another pressure source.
I will look at where I have my Greedy pressure source taged tonight.


Here is one of my data logs both pressure sensors are scaled the same.
Stock MAP sensor is tagged to the FPR vacuum lime
And Greddy is tagged to a vacuum line on the back of the manifold same one that feeds my DEFI Pressure gauge.







In my case it is the stock map that has the same profile as your G.Sensor but mine is at a lower amplitude

 

You know we nay not be seeing changes in air pressure/ acoustics effects what we may be seeing is the effect of injectors opening and closing.


As injectors open and close there is a very quick change in fuel rail pressure.
Is it possible when the injectors open and close this change in rail pressure us causing a rapid change of force being applied on the FPR

 

Yes, I came to the same conclusions on the injectors, notice the frequency is increased relative to the engine speed. I was not sure that it could be so pronounced unless some other process caused further amplification. I think I will bring a hose off of the TB and recheck it.

The scaling should be correct assuming my graphs above are correct.

 

[QUOTE=MugenRioS2k,Nov 14 2008, 11:57 AM] The

 

I borrowed a completely stock AP1 from one of the guys at the shop this weekend and did a lot of testing on the street and on the dyno.

The stock map sensor even at its stock location shoes the exact same erratic boost press/voltage that I am seeing with my MAP vac/boost source relocated to the FPR vac source.

So the stock MAP reading jumping around is normal...


So now the question is why is your Greddy pressure sensor all over the place???