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Fummins24v

Defueling at 1900 rpm fummins

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Hello all so I have been doing a lot of reading and trouble shooting, still no solutions. My truck is defueling itself at 1900 rpm then comes back to 1900rpm  sometimes even revs up at 1900 no idea why not throwing any codes . My sensors are buzzing all over the place reading high . Here is what I’ve done. Checked vss and neutral ground,New cam sensor , disconnected pcm to just run on Ecm  still problem is there . Then I tested my map sensor with ohms to ecm checks out fine  checked apps checks out fine .  I’m now thinking ground problem I checked them all and double checked. I was just messing around with ohms and tested my 5v on map to  my double connector , the one that splits to fuse box and pcm.  I got a weird resistance of .5 from map 5v pin to a solid orange wire in the white locking double connector. I then traced that back to the ecm pin #46 witch from your wiring diagram is the crank sensor sending wire. The only time I get this reading is with the ecm wiring plugged into the ecm, when unplugged I have no ohms at all ? I then thought I would check my oil sending unit beings it shares a 5v wire with map . I do not have a oil sending unit it would appear ... there is a sensor below the ecm but it only has one wire gry/Black I will try to attach pictures it goes to pin#26??? Witch makes no sense because that is the pto pin according to your schematics ?? And on top of it pin # 6 which is where the oil pressure sending wire should go is empty ? Why would this be? I am about to buy a new engine harness and ecm  I just don’t want to spend the money if it is not the problem?  I’m sure I am missing more but just can’t remember at this point . I am in great need of everyone’s expertise!  And I just wanted to say I am very grateful for all of the info everyone has contributed to this site wouldn’t have got this far without it. oh and fuel pressure is good never drops below 11

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4393B135-FBA2-42E1-8311-84E7E8B9FF65.jpeg

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I think you need to go thru more steps using process of elimination before jumping into any major expense or time for a new engine harness.

 

Fuel pressure should be no lower than 15 and that's running uphill hauling heavy. Also no higher than 19.

 

You may need to pull injectors and have them tested because I think its a fueling problem not electrical. But I'm just a minor educated diesel guy on this stuff.

 

How many miles on that engine?

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On 11/24/2017 at 11:56 AM, Fummins24v said:

My truck is defueling itself at 1900 rpm then comes back to 1900rpm  sometimes even revs up at 1900 no idea why not throwing any codes . My sensors are buzzing all over the place reading high .

3

 

With that being said I would first do an AC noise check of the alternator. If the AC noise is high you'll have to deal with that first. Part I'm confused on is  "My sensors are buzzing all over the place reading high" but "no idea why not throwing any codes". Are you using OBDII tool to get codes or the key trick?

 

Just from the video it acts like a failed ECM but that's guessing right now without more info...

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The video sounds like a major miss or fuel cut out at 1900 rpm.... I can only guess what it may be. Don't want to confuse the situation so I'm asking.... how could the ECM cause that sudden of a miss at 1900 rpm?

 

Thanks Mike

 

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If there is enough AC noise it could foul the tach signal to the ECM and do weird things from dropping fuel or adding fuel because the ECM can't clearly see the RPM's any longer. The ECM is trying to listen to all the data given to it but there is one punk kid with his bass box cranked all the way up to MAX and the ECM is fighting to do it job but having troubles listening to all the sensors. This is what AC noise could be doing. Unkonwn till the OP does some testing.

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Maybe I'm just leaning on my own personal experience a bit heavily but this sounds a lot like the way my truck was when I got my ecm reprogrammed for automatic trans and I was trying to get it hooked up correctly. My ecm didn't care at all about the pcm when it was manual, then I had it recalibrated and it stopped right below 1900 rpms. The second I had the pcm wired in correctly the problem stopped. If it acts the same with and without pcm maybe there's a bad connection between the two. 

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Hello all  thank you for your reply’s  first off I forgot to mention the injection pump was new from H&h diesel  when the motor went in . Tonight I will go through the wires that connect to the ford side again . I will probably just disconnect all that are not needed to run motor just to eliminate those . The truck is said to have 80000 miles that’s what the junk yard told me. I say the sensor readings are high because I took it to a local shop and had them plug in there high dollar ob2 and with motor running he said the map and a couple of other sensors were running high voltage. Can’t remember which sorry. I tried the ac noise test  and did not get a reading at all with my meter set to VAc 600  and vac 200 no reading on either ? It is a ford internally regulated alt . I unhooked the map sensor just to see if it would throw a code and make sure my obd2 was working and it is . Also note With map unplugged the truck runs the exact same.

I will give another update after tonight any other requests for readings of certain wires or  anything?  All input is greatly appreciated 

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1 minute ago, Fummins24v said:

I tried the ac noise test  and did not get a reading at all with my meter set to VAc 600  and vac 200 no reading on either ?

 

You DVM isn't sensitive enough. You need a DVM with a AC scale as low as 2V or 200mV to be able to see the ripple. Regulation of the alternator doesn't matter its the output that comes out of the diodes we are measuring.

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I had to go out an buy a good DVM since my lesser expensive always showed every vehicle to have 30 volts AC. :ahhh:I found a good older Fluke for 40 bucks on Craigs. I lucked out.

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Ok all so I had some time tonight to get back at the truck. With truck running I checked the A/C noise at alternator  and got a reading of .043 . With truck off battery's are at 11.9v  and test was done at 50* Fahrenheit .  Is this reading ok? Attached is a picture of my multimeter and the setting it was on when test was performed. A/C 2

 

i checked my pcm again I believe these pins are all that are needed to work?

pin# 31 32 grounded

pin#22 constant 12v

pin#2 12v key on power

pin#6 grounded 

 

 am I missing any?

 

here are all other wires that were needed to be connected per DCS instructions I went through them to check my connections and power they were all good I will ohms test them to Ecm and injection pump tomorrow . 

Green/ black- to ford violet/orange key on power

large red/white- computer power 12v

brown/white - vp44  to relay 86

red/green - vp44 power supply relay 87

lt green/black- ignition wire

orange/white- vss to ford vss

drk green- obd2 pin6

white/black- obd2 pin11

violet/brown- obd2 pin 3

pink/dark blue- obd2 pin 7

white/violet-obd2 pin 14

ground- pin 4 &5

key on pwr- pin 16

 

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Any other thoughts or advice greatly appreciated!

 

 

 

Edited by Fummins24v

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Mossyoak71 already answered your question in the post above. Pin 6 on pcm must be grounded or you'll never get over 1900rpms. Sometimes it's better to listen (or read) rather than talk (or type). You'll get more help that way.

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Sorry yes I edited my post above. I have read Mossyoak71 discussion multiple times hoping I had the same problem as him . I have checked and double checked it. I am grounded at pin 6

i also read that I need to make sure the grey/black wire at pin# 45 in Ecm goes to pin#8 at pcm  I will check this today also.

Edited by Fummins24v

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On 12/5/2017 at 5:49 PM, Fummins24v said:

I was unable to upload this earlier this is the multi meter I used to perform the a/c test

8DB517C7-0561-41C8-8867-BB9AB3A6418D.jpeg

 

I bet there is a few pups out there that have no idea what dwell angle is or what the measure even is... I like that meter! Who produces it and where can you buy it at?

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Alright an update and a question for everyone.  My question is about the oil pressure sensor below the ecm  I have a single gray black wire to that sensor and that wire goes to pin #26 at ecm is  this correct? Could this be my problem?

im very disappointed with cummins I took my ecm to them and told them my problem they took it back plugged it in  and charged me 120 for literally nothing  the only info they gave me was yes it turns on and yes it is off of a 2002 cummins truck . I then asked them to reflash it they then told me that is impossible and can’t be done. From what I have read on cummins forum I thought that it was possible? Anyway cummins was of no help so I went ahead and bought another ecm used out of Texas I feel I have checked and rechecked all of my sensors  and all of my wiring . I just can’t think what else the problem could be .

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17 minutes ago, Fummins24v said:

I then asked them to reflash it they then told me that is impossible and can’t be done.

At my local Cummins people that work there have gone full retarded and sad part is they don't know it, every time I go there it's something new with them. You literally have to tell them what to do and how or they are lost. I think Cummins head quarters have an agenda of some sort. 

I did change my oil sender once because if it leaks internally it will screw up 5 volt loop, and affect other sensors.

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@Fummins24v  have you tried unplugging the pcm? If you unplug the pcm and it still acts like this then I'd say it is bad. The Cummins dealers agree bound by the EPA. Problem is some people don't know it. Soon as you start talking about passenger vehicles ears go up and doors slam shut. It's why I'm currently deep in thought about an Insite setup. Pull a couple of these irons outta the fire first.

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Like I said before I'm not knowledgable on the electrical troubleshooting but at this point Fummins 24V, I would install a new Timbo apps getting rid of the factory Apps. you will need it for reliability anyway since its much better/ smoother Apps it kind of goes hand in hand with a new VP.

 

My factory Apps had a dead spot, did not throw any codes, but the 7-8 thousand dollar Snap On showed slight dead spot on the screen when testing. Had a Timbo under the seat and now runs perfect.

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I'm not saying Jag1 is wrong but 1850 rpms is a special number for us swap guys. Have you contacted Bob Wagner? That dude is the man when it comes to ecm's.

 

I had to relocate my apps because I needed the space where it lived for my ac compressor. I bought a Williams pedal with tps (and then another tps off eBay because the Williams one didn't have the idle validation circuitry) for under $60 and now my tps lives in the cab with me where it belongs. Every piece of heavy equipment, bus, tow truck I've ever seen has the tps inside and I gotta believe there's a reason.

Edited by Scottfunk

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