Hey guys I've got a weird issue. The map sensor randomly goes out or how ever you'd put it, like I can start my truck and quad adr boost says 47psi, I can kill the truck and start it again in 5 mins and sometimes it'll fix its self other times I'm just stuck driving with a rough diesel guzzling gold painted turd. Can ANYONE point me in the direction of where to start? 

How does it run with the Quad unplugged? 

Me. If I was face with that I would test from pin to pin between the MAP sensor plug and the ECM plug. @dripleyhas dealt with all kinds of mystery problems around the MAP sensor plug and wiring. There is a shared sensor ground for the MAP sensor which is where Dripley found his problem the ground was bad. 

It's got to be a grounding issue I would think if its making it do this, I just started her up and sure enough it's at 47psi on the quad, I tried turning it off a few time to see if it'd act right but it hasn't yet, hopefully I can get it figured out because WOW this thing can guzzle fuel like nobody's business

Hence why I suggested to do a pin to pin test to absolutely find which line is actually causing the error and fault. Add one more test being between ground and the pins this will verify none of the wires are shorted to ground which is rare but does happen. Both plugs have to be disconnected. 

 

  On 1/18/2021 at 12:50 PM, BrokeAssPainter said:

It's got to be a grounding issue I would think if its making it do this, I just started her up and sure enough it's at 47psi on the quad, I tried turning it off a few time to see if it'd act right but it hasn't yet, hopefully I can get it figured out because WOW this thing can guzzle fuel like nobody's business

May I ask what kinda mileage you're getting? Mine does almost the same thing, but in the sense of I can drive it to work and it'll run beautifully and have lots of power, but on my way home it's doggy and low on power. I'm getting 14.2 no matter what tube or fuel additives.

Imdid have a couple MAP sensors failures on mine that started very much like yours. Intermittantly cutting out and then coming back until it just quit. Sometime before the first quit I was getting a 237 code when it would act up then it just quit. Diagnosing electrical for me is about as much as hitting myself with a hammer so I bit the bullet and just replaced it. It worked for 13 months and then it blew at the same time my VP went out. Replaced both and they are both still fine. As expensive as they can be I hated just to throw the part at it. But I weighed that with hammer beating I was going and the rest is history.

 Thru all of this a member here posted up that he had found MAP sensors for 15 bucks at Fridayparts.com. At that price they sounded iffy at best but I bought of 3 of them. Put one those on about 5 months ago and it is still going strong. Maybe there is hope for them.

 One thing I did not experience was much of a change in mileage. Very low on power due to the computer not fueling the engine due to no boost. Do you have a mechanical boost in addition to the quad?

  On 1/18/2021 at 1:21 PM, TheGreatWhite said:

May I ask what kinda mileage you're getting? Mine does almost the same thing, but in the sense of I can drive it to work and it'll run beautifully and have lots of power, but on my way home it's doggy and low on power. I'm getting 14.2 no matter what tube or fuel additives.

Idk the lie-o-meter says like 15ish but I typically put $60 on Sunday evening, drive all around   Mclennan county and I'm good till Saturdayish depending if I have to go feed cows or not. When it's tripping, I'll easily use $100 in fuel which is absolutely freaking ridiculous lol

  On 1/18/2021 at 2:08 PM, BrokeAssPainter said:

Idk the lie-o-meter says like 15ish but I typically put $60 on Sunday evening, drive all around   Mclennan county and I'm good till Saturdayish depending if I have to go feed cows or not. When it's tripping, I'll easily use $100 in fuel which is absolutely freaking ridiculous lol

Yep sounds like me... I've been wondering if it was the MAP or not. At idle it does read like 15psi or something stupid. I've been noticing a weird thing while I'm driving, doesn't always happen, but it's like my truck will lose power for a split second and then it'll come back like either my quad lost power or maybe my map shoots up.....

  On 1/18/2021 at 2:04 PM, dripley said:

Do you have a mechanical boost in addition to the quad?

Yes, it's hooked to my afe intake, and I have pretty good power, hell I think im making more bottom end when it's acting up but seriously tho. Also the dreaded dead pedal will happen once in a blue moon when I crank it up and go to leave but ill kinda feather it and it'll go away once it hooks up. I've noticed too that when the map sensor is tripping, my trans will grab 1st like normal but when it's not tripping, it dont want to shift unless I let off the throttle and get back on it.

  On 1/18/2021 at 2:17 PM, TheGreatWhite said:

Yep sounds like me... I've been wondering if it was the MAP or not. At idle it does read like 15psi or something stupid. I've been noticing a weird thing while I'm driving, doesn't always happen, but it's like my truck will lose power for a split second and then it'll come back like either my quad lost power or maybe my map shoots up.....

Yea im not losing power, but quad reads 47psi  at idle lol mech gauge says 0 of course.

  On 1/18/2021 at 2:04 PM, dripley said:

Imdid have a couple MAP sensors failures on mine that started very much like yours. Intermittantly cutting out and then coming back until it just quit. Sometime before the first quit I was getting a 237 code when it would act up then it just quit. Diagnosing electrical for me is about as much as hitting myself with a hammer so I bit the bullet and just replaced it. It worked for 13 months and then it blew at the same time my VP went out. Replaced both and they are both still fine. As expensive as they can be I hated just to throw the part at it. But I weighed that with hammer beating I was going and the rest is history.

 Thru all of this a member here posted up that he had found MAP sensors for 15 bucks at Fridayparts.com. At that price they sounded iffy at best but I bought of 3 of them. Put one those on about 5 months ago and it is still going strong. Maybe there is hope for them.

 One thing I did not experience was much of a change in mileage. Very low on power due to the computer not fueling the engine due to no boost. Do you have a mechanical boost in addition to the quad?

That ground you found to be bad, it's in the main wiring harness isnt it? I've got a spare 01 harness laying around, I might throw that and another map in and see what happens.

  On 1/18/2021 at 2:18 PM, BrokeAssPainter said:

Yes, it's hooked to my afe intake, and I have pretty good power, hell I think im making more bottom end when it's acting up but seriously tho. Also the dreaded dead pedal will happen once in a blue moon when I crank it up and go to leave but ill kinda feather it and it'll go away once it hooks up. I've noticed too that when the map sensor is tripping, my trans will grab 1st like normal but when it's not tripping, it dont want to shift unless I let off the throttle and get back on it.

Yea im not losing power, but quad reads 47psi  at idle lol mech gauge says 0 of course.

Must be a bad MAP on my end...

  On 1/18/2021 at 2:18 PM, BrokeAssPainter said:

Yes, it's hooked to my afe intake, and I have pretty good power, hell I think im making more bottom end when it's acting up but seriously tho. Also the dreaded dead pedal will happen once in a blue moon when I crank it up and go to leave but ill kinda feather it and it'll go away once it hooks up. I've noticed too that when the map sensor is tripping, my trans will grab 1st like normal but when it's not tripping, it dont want to shift unless I let off the throttle and get back on it.

Have you done Wt's ground mod, checked for AC ripple on the alternator, and your battery and other ground connections? I did all that a couple years and fixed a bad splice in the 5v signal waire to the sensors. I was having dead pedal with surging issues plus other electrical gremlins. Did all of the above with new battery cables and have been gremlin free ever since. Dirty power and and bad grounds will cause all kinds of issues including trans shifting.

Does your mechanical show boost when the quad does not?

  On 1/18/2021 at 2:22 PM, TheGreatWhite said:

That ground you found to be bad, it's in the main wiring harness isnt it? I've got a spare 01 harness laying around, I might throw that and another map in and see what happens.

Mine was not not a bad ground like @Mopar1973Manmentioned. Never did find what caused the first one to go. A new one fixed it however. Until it went when the VP failed. Worked fine up until then.

There is another glued together ground splice in the wiring harness 6" or so from the ecm that could be problematic. You can find it in your spare harness by removing the loom around it.

Watch out on the spare harness. Some 01's have a different oil pressure sensor like my 02. Mine is a one wire switch and a 3 wire sensor. Not sue they play well together if different.

  On 1/18/2021 at 2:25 PM, dripley said:

Have you done Wt's ground mod, checked for AC ripple on the alternator, and your battery and other ground connections? I did all that a couple years and fixed a bad splice in the 5v signal waire to the sensors. I was having dead pedal with surging issues plus other electrical gremlins. Did all of the above with new battery cables and have been gremlin free ever since. Dirty power and and bad grounds will cause all kinds of issues including trans shifting.

Does your mechanical show boost when the quad does not?

Mine was not not a bad ground like @Mopar1973Manmentioned. Never did find what caused the first one to go. A new one fixed it however. Until it went when the VP failed. Worked fine up until then.

There is another glued together ground splice in the wiring harness 6" or so from the ecm that could be problematic. You can find it in your spare harness by removing the loom around it.

Watch out on the spare harness. Some 01's have a different oil pressure sensor like my 02. Mine is a one wire switch and a 3 wire sensor. Not sue they play well together if different.

Well my spare is the original harness out of the truck. The harness on the motor thats in my truck came with the new motor, which is also an 01 to match my truck. I've wondered if the harnesses/ ecms could be different somehow, they're the same number and everything, just didn't know if it was one of those sub-year differences....

I haven't yet done the wt mod, but I'm not having any unlocking issues in 4th. Probably something I'm going to do in the spring when it's not so clod and windy.

  On 1/18/2021 at 3:41 PM, BrokeAssPainter said:

I haven't yet done the wt mod, but I'm not having any unlocking issues in 4th. Probably something I'm going to do in the spring when it's not so clod and windy.

I have manual trans and needless to say no weird things with it. But I had other issues that the ground nod helped put to bed. If you are having electrical gremlins of any sort it is time to address the electrical system. It might not fix everything but it is worth the effort. Good clean DC voltage is what you are after.

  On 1/18/2021 at 3:33 PM, TheGreatWhite said:

Well my spare is the original harness out of the truck. The harness on the motor thats in my truck came with the new motor, which is also an 01 to match my truck. I've wondered if the harnesses/ ecms could be different somehow, they're the same number and everything, just didn't know if it was one of those sub-year differences....

I would think the new one is ok if all is working well. The oil pressure sender or switch is the big one I know of. Maybe more than I know about. But I would think the ECM would look at things differently if the wiring harness is not right. Has to be some programing differences to accommodate the sensor differences or anything else that Dodge might have changed.

  On 1/19/2021 at 12:37 AM, dripley said:

I have manual trans and needless to say no weird things with it. But I had other issues that the ground nod helped put to bed. If you are having electrical gremlins of any sort it is time to address the electrical system. It might not fix everything but it is worth the effort. Good clean DC voltage is what you are after.

I would think the new one is ok if all is working well. The oil pressure sender or switch is the big one I know of. Maybe more than I know about. But I would think the ECM would look at things differently if the wiring harness is not right. Has to be some programing differences to accommodate the sensor differences or anything else that Dodge might have changed.

I think I'm just gonna buy another map sensor and see if that does anything. Been meaning to do that, but I couldn't justify $153 sensor while rebuilding my 6.7...

  On 1/19/2021 at 1:26 AM, TheGreatWhite said:

I think I'm just gonna buy another map sensor and see if that does anything. Been meaning to do that, but I couldn't justify $153 sensor while rebuilding my 6.7...

 

If you have the time and dont mind something less than Cummins, there are alternatives. The price stopped me from just throwing the part at it originally. I now have 4 spares after buying the 3 Chinese ones. 

  On 1/19/2021 at 1:46 AM, dripley said:

 

If you have the time and dont mind something less than Cummins, there are alternatives. The price stopped me from just throwing the part at it originally. I now have 4 spares after buying the 3 Chinese ones. 

And it's still going fine correct? How long did it take to get to you?

  On 1/19/2021 at 1:53 AM, TheGreatWhite said:

And it's still going fine correct? How long did it take to get to you?

The chinese ones about one or 2 weeks. AA AZ or Orielly's stock them. Used to be 100 buck apiece but here the orielly's one that was 100 went to 200 not long ago. 

I still haven't had a chance to test any plugs or wires since its been cold as rainy and no garage lol but I'm definitely doing the wt mod first chance I get