Hey guys, I just finished my build, took the car to my tuner and we encountered a problem while doing a little base street tune. We're using Neptune and when I go WOT or even part throttle, Neptune is reading 9 inches of vacuum and doesnt go into the last 2 columns of of the fuel/ignition maps. From what I understand, Vacuum suppose to be around 0 at WOT.

My tuner says it could be my map sensor so Im going to change that and try again. I was just wondering if anyone has ever come across a similar situation and any possible solutions?

The build is:
1.8L B18C, approx 11.8 C/R
Wiesco pistons/eagle rods
jun 3 cams
ported head, with Jun valvetrain
Skunk2 IM and Throttle Body
RC 440 Injectors
Walbro 255 HP
Toda header
Full Skunk2 2.5" exhaust

As always, all opinions welcomed

 

Neptune reads what the sensor sends it. Change map sensor and/or change vacumn port to make sure you dont have a blockage issue.

 

what sensor, stock, 3bar, 2.5bar??? If anything other than stock, did the tuner setup the sensor info correctly? If not, then there is your problem, otherwise do the above suggestion.

 

And another thing to mention, atmospheric pressure is only 0 AT SEA LEVEL. If you're at a location that is anything other than sea level you will not see 0 at WOT. Where are you located and who was your tuner?

 

We were using the stock MAP sensor and are located in Toronto, Ontario.

 

You could always try another, but more than likely that's just the amount of atmospheric pressure at your location.

 

So just wondering, is there anything we can do to get the car to read the values in the last column because from what I understand, those values are what makes power. Unless Im wrong. I guess we will try another map sensor and get the car on the dyno to tell for sure whats going on.

 

I always see like 950-980mbar (and go into the 8-9-10 columns) at WOT on n/a cars while tuning. This car was seeing a max of 750mbar and staying in the 6-7 columns at WOT

 

As stated the software sees what the map sensor tells it, so it sounds like the map sensor has a problem... you're still bringing in the right amount of air regardless, so it shouldn't effect power. It's still a better idea to get it fixed and properly tuned that way.

 

Ok sounds good, Thanks alot for the help.