MAP sensor replacement

4x4dually

4x4dually

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Does anyone have any info and whether I should go back with the stock MAP sensor or is there a better one out there that works better under the higher pressures that we are putting through these engines?

I'm sure the stock sensor is only designed to see a max of 20 psi or so and I'm putting 43 to it. Could that be why it failed? Are you drag/sled puller guys and gals using stock sensors? Is there anywhere to get one cheaper than the freakin' $175 that Dodge wants for one? I couldn't beleive that. I'm on hold with Cummins right now....as usual. Cummins wants $71.41 plus $11 for a wiring harness.

The reason I'm replacing it is because I pulled it and screwed it into a test jig I made and the sensor never changes readings on my DMM. It appears to be a potentiometer that will change resistance with air pressure. Anyone have a better way to test them?

Thanks! JWB
 
Boost Voltage
0 -- 1.045
6 -- 1.48
10 -- 1.75
15 -- 2.05
18 -- 2.27
20.5 -- 2.44
 
Thanks TIM! I greatly appreciate you help! Mine's apparently stuck at the bottom.
 
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Timbeaux38 said:
Boost Voltage
0 -- 1.045
6 -- 1.48
10 -- 1.75
15 -- 2.05
18 -- 2.27
20.5 -- 2.44
Click to expand...


From this I am going to guess it is a variable resistor to alter the voltage, i.e., it has to have 5 or 12VDC applied to one side and the PCM reads the output??

I don't know, just wondering if you would see a change with no voltage applied other than what the DMM supplies??


Keep us updated, this is getting interesting :D
 
I had one go out on a 2000 Dodge 2500 4x4 Auto, and i replaced it through a Case dealership, it was alot cheaper then anywhere i could find them. But my dad worked at the napa store attached to the case dealership so i got a discount but it shouldnt be to bad of price, i believe the tractor it was off was a MX 135 but i cant remember for sure
 
You need to apply a 5VDC reference signal to truly test the sensor.
I'm one more for checking out Hoesli Diesel. Ask for Eric and tell him I sent ya.
 
Timbeaux38 said:
Boost Voltage
0 -- 1.045
6 -- 1.48
10 -- 1.75
15 -- 2.05
18 -- 2.27
20.5 -- 2.44
Click to expand...
You wouldn't happen to have the voltages for the 12valve IAT sensor?

brandon.
 
Billysgoat said:
From this I am going to guess it is a variable resistor to alter the voltage, i.e., it has to have 5 or 12VDC applied to one side and the PCM reads the output??

I don't know, just wondering if you would see a change with no voltage applied other than what the DMM supplies??


Keep us updated, this is getting interesting :D
Click to expand...

The diagram shows the sensor being feed by a +5VDC signal from the PCM. It changes the voltage due to pressure therefor the resistance has to change. Now, by the book, a DMM should read it fine using its own output, the current will just be a lot less. This being said, when my new one gets here today or tomorrow and after I pull my old one back out, I am going to hook a power supply to it at 5 volts and validate the old one is bad again as well as test the new one to the numbers posted above. There is a slight chance that the sensor needs to be powered to operate, but I doubt that it is that complicated, it is only expensive as hell but is relatively simple. Once I validate the numbers of the new one and get the truck running, I'll canabalize the old one and figure out exactly how it works. Once I do this, I'll post my findings so maybe it will help someone else someday.

Also, The numbers posted for voltage only go to 20.5 psi and at this voltage it should read 2.4 volts or so. I graphed all the output numbers and one can only assume the sensor is linear up to 40 psi with a final output of 5 volts. I'll also test the new one to 40 psi and try to prove it and post my findings.

Numbers in bold are assumed and I will try to prove them:

Map_Sensor_Data.JPG

Map_Sensor.JPG
 
I can see right now the advantages of having an EE "on staff" LOL LOL

Good info Jory, I for one am looking forward to the results :thankyou2:
 
would it b possible to jump the volts at idle , say 2 or more volts then by chance with the extra fuel dumping in could it start building boost via extra heat/fuel ????
 
I believe that's essentially what the Smarty on level 6+ does- It fuels and doesn't care about boost. It makes smoke, but not a whole lot of power.

bnraodn.
 
This REALLY sucks.

:doh: Well, SH.....T! For one, the 'bench test' failed. I can't get the resistance to change or the voltage to change no matter how I test it. I hooked the stupid thing, the new one, to an airhose with a 0-30 psi gauge on it. Then I boosted the air pressure up to 5...10...15...20...25...30...NOTHING! I tried reading resistance changes and then put +5vdc across it and still no change when reading voltage. This is some piece of work I tell you. The connector is not really great at telling you which pin is which, but I went by the factory wiring harness. Vout comes from the middle pin. The new sensor acts just like the old one did. I hope they taket this freakin' $71 sensor back! :bang

Chapter 2.
After cussing a few times, a couple cigarettes, and more cussing I thought, wiss on this stupid thing...I'll test it in the truck. So, I put wire taps on the GND and the Vout wires and ran a wire into my cab. Then I drove down the road with my DMM on my console reading the stupid thing. As soon as I started the truck, I got a Service Engine Light. I got to the highway and it ran PERFECT!!!! No skips, no misses, just plain straight boost from 0-40 psi. I got 6 miles to the filling station, pumped her full of diesel, and pulled the extra wires out of the wire taps. It ran perfect all the way back home! :rockwoot: WTF?

Chapter 3
I start her up this morning and it jumps and bucks again.:doh: The Service Engine Light is gone but it runs like crap. I hooked the DMM back to the wire taps after a few miles and voltage from the MAP sensor is fine. It reads 1.045 at idle and maxes out at 2.33 vdc at about 18 PSI and holds at this voltage for any boost above 20.

Conclusion.
I don't know what the heck is going on, but I do know it is related to the MAP sensor or circuitry somehow. That was the ONLY thing I messed with last night and it fixed it...for the first test drive. The motor was hot then and it is hot right now. I drive 30 minutes to work and it failed the whole trip. I am beginning to think it is a termination problem in the connectors on the Edge wiring harness. I had to pull on the wires pretty hard to get the wire taps on them and maybe I got a wire to connect to the pins again. I'm thinking they crimped some insulation in the pin or something causing it to be discontinuous some of the time. I will inspect that later tonight when I get home.

Ya, maybe having an EE on the team is good an all, but it is 4th and 8 and I'm going to punt! How in the heck can a stupid thing with THREE wires be so complicated that I can't test it on the bench? The PCM must modulate the signal or some funky shiznit. I can't figure it out.

Basically, this sums up my whole evening and morning......
:doh: :rockwoot: :doh:
 
in all my testing on my hard start issue i am looking at my map sensor/comp hookup at the map sensor being a possible culprit. during my hard start episodes i would just unplug the map sensor, plug it back in and it would fire right up, so i replaced my map sensor. well i still have the problems and it happens with the comp plugged and unplugged, so im stumped... what did you end up finding 4x4?
 
Now that the temperatures here in sunny Oklahoma are into the 100's with lows of 80's at night, I can't produce the problem. I never ended up buying a new map sensor and probably will have to next winter. If the air intake temp on my readout is above 75F or so the truck runs great. I did figure out that you have to power the sensor if you are bench testing it but never hooked it back up to try it. It would be so simple if Edge or someone would just explain how they interpret the signal and use it...but NO...it is proprietery...horse ****. I never took any fancy test equipment home from work so maybe if I have the problem in the fall I'll dive back into it.

The only time I got it to run right was a few time when I unplugged the sensor and plugged it back in. Just like yours it ran fine...until I parked it and started it the next morning. I wonder just how intricate that sensor is. I wonder if it has a digital potentiometer in it that is getting hosed and just has to be reset by removing power. I don't know.
 
4x4dually said:
I wonder if it has a digital potentiometer in it that is getting hosed and just has to be reset by removing power. I don't know.
Click to expand...

i was thinkin along the same lines.. i think the truck is just F&^$*#G with me now that i pushed it to 13.5, at least thats what everyone else says :poke:
 
just for kicks and giggles,,,,,,tap the middle leg,5v supply leg,with your mm..run it down the road and see if its holding its 5 full volts supply..i imagined you just watched return voltage.though if your supply was varying,you would see a variation in the output.....hmhhmmmm..i chased this same thing on my old 02,never did get it straightened out,,got tired of it,and traded it....now,,3 trucks later,ive got another 02 model,,and ill be da**ed if it didnt start doing it too...........hohn posted that his started out with the bucking problem,then went to dead pedal,and ended up being his ecm was bad...............bama
 
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I would like to find someone with a smarty to load and then reprogram my ECM back to stock and see if it just doesn't have a glitch. I really don't want to pay Dodge to reprogram it, but that may prove safer.

Luis, I just got out of the can and read your article again. So, you got a SPS turbo, comp, stage III sticks, holley blue, and a stack and make 500+ hp and 1200+ tq? What are hidin' dude???? :poke:

And thanks for serving our contry in Iraq.
 
hmmmm that is a very good point i never thought of that!! im thinkin my hard start started around the time i tried out a smarty for a few days!! hmmmm

three of the injectors are DD3s and three are DD6s so it makes twice the power:shake:
 
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