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Truck Revs and then Dies in Traffic

KRob
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KRob

KRob

Posted
Posted

I originally posted this on Cummins Forum, any thoughts or ideas would be very helpful.   

 

Truck very intermittently (probably twice in the last month), typically in traffic, at low RPM and low throttle input will start rev ing up to about 2200 RPM and then die. If I immediately try to restart it it will not catch. If i turn the key off and let it sit for a 10 seconds or so it will start back up no issue. 

So low RPM, low throttle pressure it will start pulling, it will gradually pull until about 2200 RPM and then die. Manual truck so once i notice the issue i push the clutch in, once i push the clutch in it will rev to up to about 2200 RPM over about two seconds time period.

Several months ago i had numerous electronic issues which this was one of them. Replacing the PCU/PCM (cant remember which one it is on this one) and the alternate, seemed to fix a no bus issue, and voltmeter periodically flat-lining. 

Topic was covered in this thread: No Bus & Voltage Gauge Dropping Off & Periodic Revving and then Die-ing

No Bus & Voltage......

All of those issues have gone away except the rev ing issue. 
XZT+ is still hooked up, but will probably un plug it in the coming days. 

Truck has had a Timbo app on it for 100,000 miles probably. Gut tells me it has something to do with that but i ask for your advice. 
 

2001 Dodge Cummins HO (Six Speed)  So Pump, XZT+, timbo apps.  

 

KRob

KRob

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  • Author
Posted

no cel, cheap code reader doesn't pull anything last time i check.  I dont have a scan tool.

trreed

trreed

Posted
Posted

@Me78569 @TFaoro look another truck just like mine....

So my truck is doing the exact same thing.  I've been pulling data logs with the Quadzilla, and it seems the ECM is getting 'stuck' on certain values.  I've had this issue with three VP's, two APPS sensors, and a new cam sensor.  I've narrowed it down to the Quadzilla or the ECM, but since you have the same issue with a different tuner, I'm assuming it's ECM time..

What I can suggest for you to check is ALL of the grounds, specifically the one that is tied directly to the ECM.  It's located by the starter, and the ones that run under the battery trays.

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Mopar1973Man

Mopar1973Man

Posted
  • Owner
Posted

This is not a APPS problem too many look at the APPS first.

 

I would start with AC noise testing from the alternator. Check for any error codes present on either computer. Is there any modification to the electrical system added grounds or noise filters? I highly suggest that all electrical is returned back to stock and any noise filters and extra grounds removed that are not factory.

 

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KRob

KRob

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Posted

Truck got a new PCU/PCM and an Alternator not long ago.  Besides the XZT+ and an extra set of lights there are no other electronic add-ons.

 

I will have to get a good voltmeter from a friend.  Mine doesn't read low enough to do AC noise. 

 

Kent

 

 

  • 3 months later...
KRob

KRob

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Posted

Anyone have any more thoughts on this?

 

My ABS and Brake lights went on a day ago.  I parked in a parking lot and turned the truck off...the ABS Module was humming away under the hood when i got out.  Its a loud not good hum.  I disconnected it and plugged it back in 10 minutes later with the key off and started humming again.  This will be the second ABS Module in call it 50,000 miles.  

 

Truck still periodically revs up and then dies.  

 

I also got some codes a few days ago.  

p0237 MAP Sensor

P1691

 

Like i said in an earlier post i have a brand new PCM and Alternator.  The old Alternator was the original and probably had really bad AC noise however it was replaced due to it not always charging the truck.  

 

I have to locate a voltmeter good enough to read the AC voltage noise....i also am going to have to educate myself at the same time on how to set the voltmeter up correctly, electricity is one thing i am a little dull on.   

dripley

dripley

Posted
Posted (edited)

FWIW I have been dealing with an engine surging problem for quite a while. Had repeating apps codes and occasionally 237 and 236 codes. I did replace the APPS with no help at all. I then started noticing the the MAP codes seems to come before the apps codes. I did find that messing with the MAP wiring harness Has made difference. Enough so that the surging went away. I did also replace the MAP sensor but I believe messing with the wiring made a bigger difference. The MAP, APPS, ECT, OIL, and I believe the CAM sensor all share a common ground with a splice in the engine wiring harness near the break out for the ECM. I am as dull on electrical as you but I am convinced a lot of the issues you, me and many others are seeing are tied to common problem. I dont know enough to advise you where to look, but I am going to find mine. That ground I speak of is common to to many things but a bad sensor can wreak havoc with the others. Kind of  a crap shoot on the root of the problem.

Edited by dripley
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Mopar1973Man

Mopar1973Man

Posted
  • Owner
Posted
6 hours ago, KRob said:

Like i said in an earlier post i have a brand new PCM and Alternator.  The old Alternator was the original and probably had really bad AC noise however it was replaced due to it not always charging the truck.  

 

I have to locate a voltmeter good enough to read the AC voltage noise....i also am going to have to educate myself at the same time on how to set the voltmeter up correctly, electricity is one thing i am a little dull on.   

 

Need to find about $100 DVM that has a 2V AC scale. 

 

Then measure from the BATT post on the alternator and the case ground. It should measure less than 0.05 or 50 mV AC. Anything over 0.1 AC Volt is an instant fail. 

 

Just because you replaced the alternator does not mean its good. I've seen several brand new alternators come out of the box failing the AC noise test. Matter of fact I was chasing a lopey idle issue and took my alternator to be tested on the bench it was 1.1 AC volts at full load. Comparing the new alternator in the box was 1.7 AC volts at full load. I told the tech never mind I'll keep my alternator.

 

Keep in mind my test is a zero load test vs test stand is a full load this way the fail voltage is way different. Being most people can't get the alternator at full load safely on the vehicle without causing damage. 

KRob

KRob

Posted
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Posted

I know this sounds stupid but can someone guide me to a couple of good options for a DVM?  Probably will be going the amazon route.

 

Also does anyone have experience with any of the ECU and or ABS rebuilders?

 

 

 

015point9

015point9

Posted
Posted
44 minutes ago, KRob said:

 

 

I know this sounds stupid but can someone guide me to a couple of good options for a DVM?  Probably will be going the amazon route.

 

Also does anyone have experience with any of the ECU and or ABS rebuilders?

 

DVM...I bought one of these.. https://www.amazon.com/Fluke-117-Electricians-True-Multimeter/dp/B000O3LUEI      From Plat Elec (on 6th South in Seattle)  had it the same price as Amazon, so didn't pass up. .  Don't remember if was on sale or not.  Amazon has it as 4 1/2 stars.  And a bonus with Fluke is you can sign up for their on-line course.  On-line course covers about everything under the sun.  Never knew there was so much to measure in elec. What is a "good option" I couldn't tell you one from another...reason why I like star system on Amazon.  

 

 

KRob

KRob

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Alright stopped on my way home tonight and ask my mechanic to help me for a second.   He is an older guy and when I said AC noise he groaned and said I haven't heard of that in years.  

 

We did did the test and it measured .049.  

 

Now that is a new alternator.  I tried to do the test with the awhile ago.  I have no idea if the alternator in this clip is the old or the new on.

 

 

Any opinions on any of this.  

 

Going to pull the ABS unit and send it to Moscow ID for a rebuild this weekend.  Any opinions on the ECU or the rec issue? 

 

Thx 

 

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Mopar1973Man

Mopar1973Man

Posted
  • Owner
Posted (edited)

First off you never test at the battery... Only at the alternator. So the RED probe goes to the BATT stud on the alternator and the black probe goes to the case of the alternator or the negative battery terminal. 

 

 

Edited by Mopar1973Man
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KRob

KRob

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I saw that after I posted the message so we know the first time I did it in the video I was flat wrong. 

 

This time at the shop, the mechanic did it somewhere from the alternator to the alternators case.  I read him the instruction above and he immediately understood and did it. So I am fairly confident the test was done right. 

 

 

  • 4 weeks later...
  • 3 weeks later...
KRob

KRob

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Moparman, when we tested the truck we got .049.  

 

I installed the remain ABS and that fixed the ABS issues. 

 

The truck started loosing power then having it come back on hard.  Which I have experienced before with my first box (edge ez). So I unplugged the quad xzt+.  Have been traveling so haven't been able to drive the truck.  

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Mopar1973Man

Mopar1973Man

Posted
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Posted
2 minutes ago, KRob said:

Moparman, when we tested the truck we got .049.

 

Marginally high. It will work yet but randomly cause issues. My last alternator was right there floating the 0.04 to 0.05 realm and create a random surge in the cruise control. Remember I'm a manual with fly by wire cruise so instead of the torque converter issues like a automatic has I get the cruise control issues.

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