MAP Sensor CEL after change

[zkv476]

Hey all, I've been having this weird issue after changing my MAP sensor to an Omni 3 Bar and have spent hours digging for a solution and haven't been able to fix it so I was wondering if anyone else had some ideas for me.

I bought a used Vortech kit and I have plans to install it soon using the OFT tune since I have an OFT. I decided to install the MAP sensor first just to make sure it was good and take the install little steps at a time. I currently run the OFT stage 1, and after installing the sensor I flashed an updated ROM with the new sensor scalings and limits. Everything seems to work fine, no driving or starting issues, but after about 15-20 miles of driving it will throw CEL P0068.

From NASIOC and calculating myself using the Omni calibration data in kPa, I got 9.119 psia/V and +0.164 offset. I set my scaling limits to 0 - 4.75v (0.164 - 43.5 psia). To those of you running the Omni 3 bar, what sensor scalings do you use and did you have similar issues?

[steve99]

Originally Posted by zkv476

Hey all, I've been having this weird issue after changing my MAP sensor to an Omni 3 Bar and have spent hours digging for a solution and haven't been able to fix it so I was wondering if anyone else had some ideas for me.

I bought a used Vortech kit and I have plans to install it soon using the OFT tune since I have an OFT. I decided to install the MAP sensor first just to make sure it was good and take the install little steps at a time. I currently run the OFT stage 1, and after installing the sensor I flashed an updated ROM with the new sensor scalings and limits. Everything seems to work fine, no driving or starting issues, but after about 15-20 miles of driving it will throw CEL P0068.

From NASIOC and calculating myself using the Omni calibration data in kPa, I got 9.119 psia/V and +0.164 offset. I set my scaling limits to 0 - 4.75v (0.164 - 43.5 psia). To those of you running the Omni 3 bar, what sensor scalings do you use and did you have similar issues?

Is the 3 bar omni the sensor used by the OFT 300 kit ?? if so the scaling will be in the OFT tune for that kit.

[zkv476]

Originally Posted by steve99

Is the 3 bar omni the sensor used by the OFT 300 kit ?? if so the scaling will be in the OFT tune for that kit.

No I think the OFT 300 kit provides a 2.5 bar omni. I purchased my kit used and it wasn't originally an OFT 300 kit so it had a 3 bar but I will be adjusting the OFT 300 tune's sensor scaling and using it since it's essentially the same.

[DBW]

OMNI 3 Bar MAP sensor
0.617 - MULTIPLIER
0.03 - OFFSET

That is the Metric scaling for it in bar.

[zkv476]

So I tried it with the PSI conversions (8.948 psia/V and +0.435 psia offset) and still threw a P0068 . The strange thing is it corresponds with the stock sensor on stock scaling... I recorded the atmospheric reading with engine off and got 14.65 psia and then started it, let it idle for 2 minutes and got the idle reading of 4.93 psia.

I then flashed the same map with the stock mapping and got the same values. I did drive around and let the ECU do some learning before taking the new values down. Any ideas or is it just a characteristic of a sensor with less fine intervals causing the code?

[steve99]

Originally Posted by zkv476

So I tried it with the PSI conversions (8.948 psia/V and +0.435 psia offset) and still threw a P0068 . The strange thing is it corresponds with the stock sensor on stock scaling... I recorded the atmospheric reading with engine off and got 14.65 psia and then started it, let it idle for 2 minutes and got the idle reading of 4.93 psia.

I then flashed the same map with the stock mapping and got the same values. I did drive around and let the ECU do some learning before taking the new values down. Any ideas or is it just a characteristic of a sensor with less fine intervals causing the code?

wack this in your gogle search

"P0068 site:www.ft86club.com"

also see here

http://www.ft86club.com/forums/showp...31&postcount=6

few people had problems with these onmi sensors
and some with vacuum leaks due no clamps on evap lines under intake manifold

might also be crook maf sensor

put oem back in to see if no codes thrown that should rule out vacuum leak

code related to correlation between maf sensor and throttle position

[zkv476]

Yea I've tried searching that but not much useful information has come up, its mostly "oh my tuner sent me a new tune" and it went away. I've been running on the stock sensor since yesterday morning and no CEL in 100 mi

Sent from my SCH-I545 using Tapatalk

[Sportsguy83]

@jamesm

[steve99]

Originally Posted by zkv476

Yea I've tried searching that but not much useful information has come up, its mostly "oh my tuner sent me a new tune" and it went away. I've been running on the stock sensor since yesterday morning and no CEL in 100 mi

Sent from my SCH-I545 using Tapatalk

did you set the DTC limits as per the above post to 0 and 5 volts ?

[zkv476]

Yes, although I had them set 0-4.75 which based on scaling should be 40+ psi on the top end, since I wanted it to fault out if the sensor really failed. I also thought MAP limit DTCs were P0107 low and P0108 high.

[zkv476]

Not so much a solution, but I figured I'll post if it ever crops up in the future for someone else. Turns out that it is just a characteristic of these sensors working in a different range and reacting quicker than originally expected by the ECU I presume. The OFT300 map uses the 2.5 BAR Omni and simply has P0068 disabled in the map that was sent to me so it seems to be a non-issue, provided I rescale for the 3 BAR.