Anybody every installed...

[Country Mav]

Anybody ever installed the jumper harness in between the PCM and the MAP Sensor? A Ford Mechanic told me that it would allow more boost. Anything to this that y'all know of? I originally thought that he had said it would improve econ...

Originally, this thread said "improve fuel economy" because I'm pretty sure that's what he said... now he says that it just allows more boost... I'm trying to find out more about it.

[NYC F-350]

New one on me. Never heard that before. Subscribing to hopefully learn something here....

[justinmix]

Never heard of it either. I would think it would be easier to install a boost liar or a tuner then to go thru all that.

I think he was just blowing smoke up your butt......

[Country Mav]

He's saying that it can be done in conjunction with my tuner. He knows my mods and the tune... That's why I'm asking y'all, lol. I've never heard of it either.

[Hemicbx]

I think that mechanic needs to stick to working on the ford tractors.

Running a jumper from the MAP can really only do one of 3 things:
1) make the PCM believe that the MAP sensor is maxed out and seeing 51psi boost (page 63 of the bible)
2) make the PCM believe that the MAP sensor is putting out 0v and therefore seeing no voltage (page 63 of the bible)
3) make your wallet see low by shorting out something expensive

I have to think that if the PCM were to see a 51psi signal it would take protective measures; likely not even run nor start. Remember, with a fixed jumper it would see the signal ALL THE TIME and I doubt that it would pass sensor validation at startup.

I suspect that if it saw 0 psi it would either permit a dangerous overboost situation and never know it or it would fault upon start up because it sees no atmoshperic pressure (it's unclear whether that sensor is an absolute pressure sensor or a gage pressure sensor and therefore just measuring pressure above atmospheric)

Either way, with the complexity of our trucks, I just can't see a jumper wire in a circuit designed for a variable voltage as beeing an OK thing to do.

I do agree that with some older EFI systems that there was the ability to make some sensors read max or min and acheive some benefit, but that was waaaay long ago.

-Hemi


PS: no comments in this post were intended as disparaging against tractor mechanics

[Country Mav]

Haha, you sound pretty official. I believe I'll take your statements. I was wondering how this would affect the truck. Originally, he told me it would really help my economy, because there is something on the truck that the computer ignores and just receives a constant signal resulting in a constant somewhat rich state. Now he's saying that it only allows more boost and won't affect economy. I don't know if he's forgotten our original conversation or if he's forgotten something else... Whatever the sensor was that he said the computer ignores and uses a fixed signal to determine the fuel mix, he originally told me that the reason the computer was programmed to ignore it is because on the early 6.0s this sensor would clog and not read correctly. So Ford programmed the PCM to ignore the sensor and recieve a "dummy" reading that as I said, results in a constant rich fuel mix. Has anyone ever heard of this?

[NYC F-350]

Sounds more like the EP (exhaust pressure) sensor.
I know that the programming was changed for this sensor, but it is still used by the PCM but in a different manner. One way it is used is to ensure the appropriate boost pressure of the turbo (by comparing MAP and EP), and another is the part of the programming that compares the MAP sensor, EP sensor, IAT2 sensor to determine proper egr valve flow (which is what triggers the egr delete 'insufficient flow detected' code). I don't see what advantage there would be to a jumper wire on that.
Still sounds a little on the side.

[Rmorgan711]

sounds like a front row ticket to a trainwreck