Thanks for any input.
I have a 2000 F350 4x4 CC 7.3L with a switchable chip I normally run 80 or 100 HP tunes.

Why does my truck run better with the Mapp sensor unplugged? It does not blow smoke and it has better excelleration.
It does this with the old Mapp sensor and the new one I purchased the only thing is the SES light is on because it is unplugged.
Just wondering why it runs better with out it and will it do any harm.
Thanks

 

There's a good chance it runs better with it unplugged because you're overboosting what the PCM is programmed for. Once the PCM detects a certain level of boost from the MAP sensor, it defuels the engine.

You can build a boost fooler with a pressure regulator from an air compressor set to about 22 psi, or you can just buy a something like this. Boost Pressure Relief Valve

 

Most tuners have a built in OCR on their tunes from what I have heard. I ha e run 3 different reputable tuners and they all did. I never got a light and have built 30+ psi in stock Turbo with WW

 

OK even at slow speeds it runs better maybe only 3 to 5 lbs boost.
Mine does not seem to defuel until it hits 25 or 26 psi.
Thanks for the info
Al

 

Which tuner? It should nap without a MAP. This sounds like there's something else going on in there.

 

Agreed... it should be a total slug with it unplugged.
Something be wrong that digital psychology may fix...

 

Morning, It is a TS Performance switchable chip. Yes I thought unpluging it would make it blow smoke and not run as well.
But If I unplug it it runs better and blows less smoke even when I punch it than when it is hooked up I am just trying to find out if there is something else going on.
And that is with a new or old Mapp Sensor.
Thanks AL

 

Either you have a crazy hot tune in there with the wrong sticks, or something in the truck is lying to the PCM.

Is this an ebay chip or similar, or did you order it specifically for your vehicle from a reputable vendor?

 

Yes I did get it off ebay it is a TS Performance chip same as the ones on there now. I have had it quite awhile so I dont remember everything.
When I have the Mapp hooked up if I am just runniing around town with the same tune it will start blowing smoke and act like it is loading up until I step on it and it blows alot of smoke and then will run fine for a little while. That is why i thought I had a bad Mapp Sensor but the new one does the same. With it unplugged I watch my exhaust temps and they are not high.
Just had me confused it doing the opposite of what it should.
Thanks for the replies

 

Dude. You gave a 444 cubic inch diesel beast (that can hurtle 20,000 pounds of steel down the freeway) a brain transplant... off ebay. I would strongly urge you to remove it and call a tuner, to get it programmed for your truck before you burn something expensive down.

I remember a joke about Larry the Cable Guy getting a vasectomy at Sears... and having an unexpected reaction from the garage door remote.

 

Maybe
It has been on for years probably 60,000 miles at least

 

I can see these monsters taking a beating for a long time, and I'm not saying you'll burn up for sure... but I've seen photos of damaged pistons from improper tunes (as well as a number of other nasty events).

A balanced tune will give you almost no smoke, less heat, no reduction in 0-80 time, and actually increase your MPGs... or stay with what you have.

FWIW, my "balanced" system peaks at about 1250 degrees EGT (sensor on manifold), burns clean at WOT, gives me 16-19 MPG (depending on the itch on my foot), and delivers about 400 HP at WOT. I am in no way saying my truck's better than yours or that you can't achieve everything with your truck that I have (except the HP without major hardware upgrades). I am saying I know who programmed my truck.

 

Who's programming is on the chip? TS produces a chip that many different programmers use. TS also sells chips with their own tunes on them.

If your issue is happening at slow speeds and low boost levels too, the first thing I would do is remove the key from the ignition and pull the chip (leaving the key in while pulling the chip can fry the PCM). Test drive again without the chip with the MAP sensor plugged in and unplugged.

If that makes no difference at all, check for chaffed wires or a short in the MAP sensor wiring or a bad connection at the pigtail, etc. Also see if you can find someone with a 7.3 and install one or both of your MAP sensors on their vehicle to make sure they are working properly. Just because a sensor is new doesn't always mean it's good.

 

Ok I am not trying to argue, I just was not sure why things were happening
What would you say was something I should look at? I am not up on all the tuners. i did try the DP tuner but was not happy I am not sure if this is the type you are talking about. What brands?

 

F350 Thanks
I am not sure who's programming it is I thought It was from TS but not sure.
I will try doing as you say tomorrow after I get home from work.
Also I do have the Ford AIS and a 4" exhaust turbo back.
Thanks Al