Function of the MAP sensor with these HOT programs? - Diesel Forum

DZLJIM · 05-18-2005, 11:42 AM

With all the wild programs for our trucks now, how important is the MAP sensor in relation to preformance gains?
In other words, we used to have several different MAP mods that have faded away now. Is the programming overriding the MAP sensor, or changing it's input in some way?
The reason I'm asking is with my twin turbos, I have the fuel regulator and the map sensor receiving boost from turbo #2, so the most it should see is around 25 psi or so.
Should I still have the MAP seeing engine boost numbers? I figure if it sees 60 psi, it won't matter much over 25 anyway. [img]/ubbthreads/images/graemlins/shrug.gif[/img]
Any thoughts?
Thanks.

Vengeance · 05-18-2005, 12:21 PM

NO! You do not want the map to see that much boost. It will affect the truck! The map sensor also has a diaphram in it you can shred with those kinds of numbers. You need to put a regulator on it that limits it to max of 22 psi, this will give you the best performance.

BIGBEAN · 05-18-2005, 01:58 PM

Jim, hook it up to your small turbo so that it sees boost off idle, teh pcm fuels off of that so if you are goin off teh big turbo it wont see any boost until it spools. Just put a regulator on it so that it wont see more then 20 and you will be fine.

GSXRTURBOQUAD · 05-18-2005, 04:23 PM

I agree! The reg solved my issues immediately. [img]/ubbthreads/images/graemlins/biggrin.gif[/img]

ThreeStarJR · 05-18-2005, 10:40 PM

For us guys that are still learning, how can you tell what shape the map sensor is in? I've never seen anyone post that a code is thrown for a faulty map sensor...If it has a mechanical diaphram then that means age could effect its signal to the pcm, correct? thanks for any info.....oh yea love the extreme burns....... [img]/ubbthreads/images/graemlins/eek.gif[/img]

95_stroker · 05-18-2005, 11:38 PM

In addition to what ThreeStarJim is talking about, I am assuming that my map sensor is what is pulling the plug on me right now. The truck pulls like the devil up to about 22 psi boost then she levels off. So I am guessing that I am defueling right about there? Fill us idiots in on this MAP regulator.

ryanPSD · 05-18-2005, 11:44 PM

It's basically a blow off valve on the line to the MAP sensor that will release air once it reaches 20-22psi. This is the highest your sensor will see and so it will keep fueling your engine [img]/ubbthreads/images/graemlins/biggrin.gif[/img] Put the boost gauge before the regulator and you will see what your actual boost is.

I got this one. Some I think make one for cheaper but I was already buying stuff there so I picked it up too. I haven't really passed 20psi yet since I have no chip or injectors. That will change soon enough [img]/ubbthreads/images/graemlins/smokin.gif[/img]

DZLJIM · 05-19-2005, 06:06 AM

Yeah, OK. That makes sense. I already have the reg, too.
Thanks Bean and V.
[img]/ubbthreads/images/graemlins/wink.gif[/img]

GSXRTURBOQUAD · 05-19-2005, 04:55 PM

[ QUOTE ]
It's basically a blow off valve on the line to the MAP sensor that will release air once it reaches 20-22psi. This is the highest your sensor will see and so it will keep fueling your engine [img]/ubbthreads/images/graemlins/biggrin.gif[/img] Put the boost gauge before the regulator and you will see what your actual boost is.

I got this one. Some I think make one for cheaper but I was already buying stuff there so I picked it up too. I haven't really passed 20psi yet since I have no chip or injectors. That will change soon enough [img]/ubbthreads/images/graemlins/smokin.gif[/img]

[/ QUOTE ]That's not a regulator, that's a blow off valve(kinda expensive too). Home Depot sells mini air regulators(Husky) with a gauge for $20 + a couple barb fittings, works very well and is adjustable [img]/ubbthreads/images/graemlins/wink.gif[/img]!

ryanPSD · 05-19-2005, 07:55 PM

Ahhh whatever, I just know I have that little black thing and it won't let the map see over 22psi! [img]/ubbthreads/images/graemlins/rolleyes.gif[/img]

Stymie · 05-19-2005, 08:20 PM

I have the BRV from dieselsite and it has helped on the topend quite a bit. They have a pretty good arguement on there site as to why not to use regulators(they should argue against them, they are the competitor) and i am to lazy to gather the parts, so i bought theirs.

Powerstroke2000 · 05-19-2005, 08:29 PM

[ QUOTE ]
That's not a regulator, that's a blow off valve(kinda expensive too). Home Depot sells mini air regulators(Husky) with a gauge for $20 + a couple barb fittings, works very well and is adjustable

[/ QUOTE ]

Joey, would you have any pics of this regulator you use? Also, perhaps a lesson on the differences on regulators and blow off valves? [img]/ubbthreads/images/graemlins/shrug.gif[/img]

Dale

gtspowerstroke · 05-19-2005, 08:54 PM

A regulator regulates the pressure to a predetermined amount. A blow off valve blows off the excess boost above the predetermined amount. I have run up to 35 psi of boost in my truck and have not had any CEL problems or defueling problems. It seems to be more of an issue with the SDs and the '97 cali trucks. On the SDs you can also get the same function by installing a resister or diode or something like that. I don't recall the details on it though.

ThreeStarJR · 05-19-2005, 09:24 PM

Rodney (Blue Mule) and I had a discussion about the cheap regulator not to long ago, Rodney asked a very good question; if the regulater is allowing 20-23 lbs to the map sensor is that pressure "locked" between the regulator and the map after the boost(preregulator) is below 20-23 lbs? If so, what effect does that have on the map signals?
During the proceedure of setting the pressure on the cheap reg. I used the air compressor reg. to check various pressures,(trying to simulate boost rise and fall),and the cheapie guage would mirror the compressor guage when both fell below the setting on the cheapie. In my mind I thought I had proven there was no "locking" of pressure, after Rodney asked now I'm not so sure. I promised Rodney that I would put my boost gauge post regulater to check pressure between regulator/map to see what the map was truly seeing, but I haven't gotton around to it yet...has anyone tried this? Think this procedure would work?

bullridin_fool · 05-19-2005, 09:35 PM

the reg. that i run on my map line does bleed the pressure off between the reg. and the map sensor. i believe there are some reg. out there that do not bleed the pressure off. mine stated right on the package that it was designed to this.