School me on a Baro sensor/Tech specs

[Rideracelivemx7]

Moved from sea level to 3500 feet. Truck was a slug, smoked and didnt make any power. Fast forward to a cold day in the 20s and under it rips. i get it, cold dense air is going to effect these trucks or any boosted engine especially with some thin air. A day in the 40s its a slug again, wont even squeak tires if you smash the skinny. on a colder day its hard to keep them from spinning if you get on it a little too much.

Now i talked to my tuner and he said the baro sensor should be pretty much maxed out to help with timing and burning fuel a little better, however a 15 degree temp changes and its a whole different truck. So i unplugged my baro sensor and no immediate differences as far as daily driving goes. From what i can see the truck seems to run much harder on a warmer day when you smash it but doesn't seem like its fueling as much.

On a warmer day i usually need to keep it in a small tune because it just wont make any power on a hotter tune so i said hell with it ill unplug the baro and tried a hotter tune. I tried my GH street tune which is usually pretty mild up here and it surprised me by getting a little sideways.

Assuming a BAD sensor, what does it do to the computer and what does the computer fault to when the sensor unplugged? I just want to make consistent power as long as i can while understanding if im on the right path or not.

 

[Dan V]

As I understand it, and could easily be wrong, is that the baro sensor is inside the PCM. The MAP on the other hand is mounted just above the heater box (on SD's).

One of the tuners that posts here will give you the real true info though.

 

[gnxtc2]

On the pre 99.5 PCM, the BARO sensor is under the steering column. The later PCM, the sensor is inside the PCM.

The BARO sensor control fuel timing and glow plug on time.

I was playing around with the BARO sensor on my truck yesterday. When I unplugged it, it set a soft code (no CEL) and the trans shifting was off. If the sensor goes bad while driving, the PCM uses the MAP sensor.

http://www.thedieselstop.com/faq/9497faq/tsb/tsb/sia/sia00039.htm

Billy T.
[email protected]

 

[Rideracelivemx7]

very interesting thank you. I honestly would never have known my baro was unplugged if i didn't do it myself. Maybe ill switch mine with my girls truck and see if i notice a difference or power at all.

I do have an air pressure regulator as my boost fooler which is real touchy on whether it lets the PCM see just a couple pounds of boost or full boost then trips out so that could also be why i felt it wasnt fueling as hard. Ill play with it today and get back to you!

 

[Rideracelivemx7]

So I haven't had the chance to steel my girls baro sensor yet but I just made a quick beat run with it plugged and unplugged. My hot tune barely clears 34psi being 55 degrees out. I watched it smack almost 50 when it was cold out last week. What the effff

 

[old man dave]

Maybe its one of the temperature sensors?

 

[Arisley]

Moved to the OBS section.

 

[Rideracelivemx7]

Dave, i had found out my baro was not reading at all, jumped a wire and got it reading like it should. We also installed an air temp sensor as the trucks never had one and it all made zero difference how the truck runs lol pretty sure im stuck with the truck being a slug at higher elevation on warm days

 

[Tom S]

One of my initial checks when I scan a truck is to compare baro to exhaust back pressure with the engine off. At my altitude, I am looking for around 12psi.

I do not think you should be feeling that extreme of a difference in the narrow window you described.

 

[m j]

air temp sender is at the air filter on my OBS

 

[Rideracelivemx7]

yeah there is certainly something up, it was warmer earlier in the day and the truck went good but not 100%. It had cooled down quite a bit towards the end of the day where it had rained as well and the truck pulled like a freight train. Glad to feel that power again but its like an on off switch of a 100hp difference.

I have been looking into 4"downpipes as i still have a 3" and my BP is much higher than boost. To my understanding, 4" will make all the difference with a large frame turbo