Man, this isn't a typing skill problem.

 

Like I said before, I call things as I see them. If you could learn to type correctly and to speak proper english I *might* take you a bit more seriously. It is kinda like that "question mark guy" on TV. He could sell the best product in the world, but I just couldn't take a guy wearing a question mark suit seriously. Acting professional even in a non-professional environment goes a long way.

The pic in my gallery is a BD X-monitor. I now have an Attitude, The X-monitor is a very nice product. The guages were more accurate and refreshed faster than the Attitude, but the locations clashed.

 

Well mister, why don't you just go stand in the corner until you can change your "Attitude".

Sorry, couldn't resist.

 

I confess to nothing!

 

Doing some researching I found that one of the performance boxes uses the same 5v at the MAP and fuel rail pressure sensor to power the box. Using TTL logic the power consumption isn't that high, but I'm very concerned about the 35 ohms drawing 143mA off of the ECM. I would feel better if the value was 100 ohms so it keeps amperage draw down to 50mA. But I don't really know if 100 ohms will have any performance gains. Guess I will have to go out and measure for the baseline on voltage and resistance on the MAP sensor.

MikeyB

 

left it unhooked one day, doing a CAI on a buddy's ....threw a big fat code ASAP....and did not clear till drove hour or so, after reconnecting...

i did not think an IAT would do that.

so back to my FIPK, i wonder how it affects the equation, being out of the intake plenum, and flow of air?

seems like the air flowing over it would cool it more, and the ECM would have an algorithm to accomdate that, and since mine is hotter, the ECM is wrongly estimating true ambient air temp.

Maybe I could put in my AC vent? with a 35ohm resistor?

 

SuperDuty Is The Shiznit!!!!!!!! No im serious you have on killer set-up. like smokin05 said put an allison behind that cummins and your the man.

 

Ok I am really going to go slow here and explain...

1 the yellow/pink is the supply voltage not the blue!

2 how can you say 35 ohms is too much load? refer to ohms law....you would have to know the impendence of the cir on the blue wire going to the ecm...its not a ground...so you cant assume the 35 ohm resistor is going to put that amount of power through it? Who ever wrote this was not thinking all the way through how much load does the sensor put on the yellow/pink wire...if it can take 5v and put out 5v? And to finish on the yellow/pink wire thing who here remembers the a/c wire short problem? Where is rubs through to the frame? And shorts out to ground.....guess what wire that is? that’s right the yellow/pink .......not that shorting your 5v signal to ground is healthy for your ecm...but I never read anyone say oh yeah it burned out my ecm too? and that’s going to be much much more load that some silly 35 ohm load in a 3.75 differential hooked to an electrical cir that I already said its not a ground its a ecm so there is actually a capacitance to this cir....the load on the circuit is so small that the voltage will rise for about a min and a half from 1.5-1.65 from the moment the resistor is in place...cause there is such a small load on the other end...remember the resistor is changing the output from 1.25v to 1.65v so now the sensor itself can go as high as 5v output that’s going to be way more load on the yellow/pink wire that the resistor that made a 0.4v change

Next the sensor is on the drivers side of the engine...not at the air filter...don’t mess w/ that thing

Also don’t remove the sensor it’s GOT TO WORK! Or your truck will not run right!

last this mod is NOT changing the injector pressure AT ALL the ecm controls the fuel as it always would (concerning the pressure rail) it tricks the ecm into thinking the boost is up more than it is just slightly so it remaps the time of injection and the amount of fuel injected be the injector pulse with..(Time the injector is allowed to stay open) NOT THE FUEL PRESSURE!

With that said have fun guys ....this probably wont help if your "boxes" already have boost fooling built in

ps. i us spel cek this thim

 

smokin05 check your pm

 

Air flow over an object (think wind chilll) will only lower the object down to the temp of air moving across it...If the air is 30 degrees, air moving over it wont drop the objects surface to 20 degrees...

The only reason something would be warmer (or cooler) than ambient temp is conduction (contact with heat), or radiation (complicated but you know anyway).....Convection (air flow) will negate the other 2, bringin the objects surface back to ambient temp

The IAT sensor will register the temp of the air in the space its confined in....If it is in the stock airbox, it measures the temp of air coming through the filter, which is drawn in from the fender....If the IAT is laying out like with a BHAF or other intake, its measuring whatever air is around it....

Now, the IAT also measures barometric pressure....(14.7psi sea level) The turbo creates a difference across the system, say 25psi boost...That 25psi is actually 39psi, but we measure it as 25psi above atmospheric pressure....

So the IAT and MAP together work like a Mass Airflow Sensor on a gasser...Pre turbo pressure +/- post turbo pressure= mass air flow (Or something like that)


Anyway, with the IAT in its normal position, it *should* register a decrease in pressure within the stock intake=Venturi principle...With the IAT laying out unconfined, there is no Venturi effect...HOW DOES THIS AFFECT THE ECM???

Seems to me that a differential in pressure pre/post would affect fueling

Stock:

12psi IAT 25 PSI boost

IAT laying open:

14psi IAT 25 boost


2psi difference in the above assumption....Would the ECM add or decrease fuel, depending on engine load, given those variables??


If so, could there be a companion mod for the IAT, similar to the MAP mods smokin has done???


Does my ramble make any sense, or am I pulling stuff outta my **** here??

 

"how can you say 35 ohms is too much load? refer to ohms law....you would have to know the impendence of the cir on the blue wire going to the ecm..."

You said that the output voltage of the sensor is 1.6V. Lets assume the supply voltage doesn't pull down. It stays at 5 volts. So the current through that resistor (and INTO the output of the sensor) is (5V-1.6V)/35ohms = 97ma.

So... you've taken a device that was designed to supply a bit of current (5-10ma) to a high impedence input on the ECM (ADC input) and now you are running 97 ma through it. Not good.

Now, what happens if that sensor ever sees a vacuum, maybe during a rapid lift off when shifting. Say the output voltage of the sensor goes to 0.5V. (5V-0.5v)/35 ma = 128 ma. That current is going into the output of the sensor. There is no other place for it to go. The input impedence on a ADC input on a micro controller is typically 10-100K ohms.

"Who ever wrote this was not thinking all the way through how much load does the sensor put on the yellow/pink wire...if it can take 5v and put out 5v?"

The pink/yellow wire is an over current protected 5V supply line. Cummins has done a great job of making the ECM short circuit proof. *If* one tries to get too much current from the supply, it drops the voltage to protect itself. That 5V line also supplies the rail pressure sensor. If the 5V supply drops to it, so will its output and suddenly you are boosting the rail pressure. At this point you have to be concerned about your injectors standing up to that pressure.

Sensors on these engines typically draw 5-10ma each. That 5V supply isn't designed to supply an extra 100ma to anything.

"And to finish on the yellow/pink wire thing who here remembers the a/c wire short problem? Where is rubs through to the frame? And shorts out to ground.....guess what wire that is? that's right the yellow/pink .......not that shorting your 5v signal to ground is healthy for your ecm...but I never read anyone say oh yeah it burned out my ecm too?"

When a short like that occurs, the supply circuit goes into current limiting mode and that probably has some thermal limitations. The ECM will stay alive when it happens occasionally, but it isn't designed to run like that forever.

"and that's going to be much much more load that some silly 35 ohm load in a 3.75 differential hooked to an electrical cir that I already said its not a ground its a ecm so there is actually a capacitance to this cir....the load on the circuit is so small that the voltage will rise for about a min and a half from 1.5-1.65 from the moment the resistor is in place...cause there is such a small load on the other end...remember the resistor is changing the output from 1.25v to 1.65v so now the sensor itself can go as high as 5v output that's going to be way more load on the yellow/pink wire that the resistor that made a 0.4v change"

The current through the resistor is calculated as I demonstrated above and that current is going INTO the sensor output., a device that was designed as an output device.

 

So what your saying is that " IF " your engine manifold pressure went into a vacuum the voltage differential would be more significant? And possibly damage the sensor? I guess that is possible but I doubt that simply by reading how the sensor works its very unlikely.....more likely the sensor will just quit working like another sensor after it gets old....but maybe we need a diode.....? Maybe you’re on to my level two mod?

is the typin ne beetter?

 

Smokin,
I gotcha on that part, and the resistance at 0 psi is not 0 ohms. Your circuit is a voltage divider with a variable resistor as the sensor.
Did you also do a max boost reading? For both voltage and resistance?
This will go a long way in setting the baseline for the MAP range.
I would like to see the numbers.

MikeyB

 

alright then. so...can smokin's mod be improved upon superduty? do the "for sale" boxes i.e. edge, quadzilla, bd, etc...do the same thing? or are they operating on a different circuit?

 

"the voltage differential would be more significant?"

I thought you were an electrical expert ?

The current that goes through the resistor is

(Vsupply - VsensorOutput)/35ohms.

Vsupply is 5V, unless the current is pulling it down.

VSensorOutput is whatever the sensor is outputting. You say 1.6V at atmospheric, so I used that to get the 92ma. If the sensor output goes to 0.5V under vacuum, more current goes through the resistor because the voltage across it increases.

And that current does INTO the pressure sensor. A device that was designed to DRIVE a HIGH IMPEDENCE load.

I don't know how long the sensor will last.

Like I said, if you REALLY want to do this mod, the proper way would be to take the output of the pressure sensor and feed it into an OPAMP circuit so that you aren't loading the sensor like you are.