Problems with a 2001 H.O. Cummins

[E7mack96]

Hello, I am new to this forum. I Need to know about the MAP sensor. My 2001 is registering 1. 05-1. 10 volts at no boost. TST says this is ok, However, My TST box is adding fuel at idle. This box worked fine on my 1999 ram. The box is a new style programmable version. Mark said it did not need re-programming. What is causing it to add boost at idle????

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2001 3500 QC 4X4 Cummins H. O. & 6 Speed

 

[Terry]

How do you know it's adding fuel at idle? Is it raising your idle speed?

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99' 2500 SLT, Quadcab, Long Bed, 4x4, White/Driftwood, Agate Leather, 4WAL, Auto, 241HD, 3. 54 Limited Slip, Rancho 9000's, Air Lift Super Duty's, Hallmark Cachara LTD 9. 5ft Popup Camper, Boston Whaler Outrage 17'

 

[Vaughn MacKenzie]

Mack, they changed the MAP sensor in 2000 (or 2001). Anyway, the old ones read 0 volts and zero BOOST, but after 2000 they are set up to be zero volts at 100% VACUUM. In other words, you will not get a zero voltage unless you take your sensor and stick it in a jar and suck all the air out. That is why your TST box is confused and I don't understand why they didn't have you send you box back in to be reprogrammed #ad


Vaughn

 

[CCollar-OLD]

I was under the impression that with 98. 5-99 models, zero boost = . 5 VDC +/- . 1 VDC.

With the key on but engine not started, you can measure VDC across pins 3 and 7 (batt ground) on the TST wiring harness. This is the reference voltage.

Oddly enough, when I first start my truck in the morning and let it idle, I see the green LED slightly illuminated. I would bet that this is NOT the PM3 adding fuel, but rather the LED indicating that the ECM is doing something for warm-up purposes. After the truck is warmed up, and I sit at idle, the green LED doesn't light at all.

Just for kicks, you can measure across:

pins 1 and 5 (chassis grd), which is the keyed 12 VDC power source.

pins 9 and 5, which is the injector pump voltage.

Best,

Craig

 

[E7mack96]

Gentlemen, The voltage across 3 & 7 is 1. 05-1. 10 volts. It is definately adding fuel. Idles between 800-1000 rpms with box on. Fine without box on. Mark states that box does not need to be re-programmed. Is he mistaken? The green light is on bright, Not dim as in a liitle boost. When engine is off, the green light does NOT light, thereby passing the wiring test.

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2001 3500 QC 4X4 Cummins H. O. & 6 Speed

 

[Little Bill]

Below are map outputs for 2001 and pre-2001 sensors.

2001 ETH & ETC
PSI -- Volts
0. 0 -- 1. 07
4. 8 -- 1. 41
9. 7 -- 1. 73
14. 5 - 2. 06
19. 4 - 2. 39
24. 2 - 2. 72
29. 0 - 3. 05
33. 9 - 3. 38
38. 7 - 3. 71
43. 5 - 4. 04

2000 & earlier
0 ---- 0. 52
20 --- 1. 98
25 --- 2. 4
30 --- 2. 79
35 --- 3. 18
40 --- 3. 62
45 --- 4. 09

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2001 QC SLT SWB ETH 6SP JRE Spa Fabritech Practical Solutions

 

[Hale on wheels]

So if you make a circuit to change the voltage output to the MAP sensor, you should be able to fool the truck into putting out more boost without cutting the fuel off. Is this how the other boost modules work?

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Cody Hale
01. 5 2500, QC, 4x4,Auto
Gig'em Aggies!