Engine wont idle
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Amateur
Joined: Mar 2011
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Engine wont idle
I posted this 4 days ago on another forum and it got 0 reples. So I hope that you guys can help me out.
I got my truck a few months ago and this problem is just driving me NUTS!!
Truck: 2004 2500 RAM, 6-spd stick, Cummings TD with about 160k mi.
Mods: Edge Aptitude set to "0" Stock mode.
In general the truck runs great. Passed emissions 2 months ago with no problems. I have put about 4000 miles on it without issue. Drives and pulls like a freight train.
The problem is during idling. When the problem began, I thought it was some sort of idle economy mode that was not working properly. After a few seconds or minutes of idling (like when sitting at a light), the engine would just sutumble, the computer would try to save it by surging it, but most of the time it would just die. I have had it before when I leave the truck idling and it will idle just fine for 5+ minutes, then the problem starts for no reason - the engine starts to surge and sometimes dies. Other times it gets so bad that the motor dies between gear shifts! Let me tell ya, having your power steering and brakes fade by 90% when coasting around a downhill corner in a 8500lbs truck, is not fun!
When outside the truck I can hear what sounds like a relay clicking coming from under the hood when this is happening, but this may be normal.
This is where it gets a bit strange. After months of this, I began to notice that the problem gets MUCH worse when it rains. I live in Seattle, so it almost always rains, but on a recent trip to Boise the problem went away completely for 4 days, until one day in Boise it rained and the truck started doing the same thing. The following 6 days were sunny and the problem went away again. A day after I got to Seattle, it started again.
I suspected that something - maybe the air filter, a sensor, or some relay was getting wet and causing a problem.
Here is where it gets REALLY strange. Upon further obervation, I noticed that the problem really starts just before the rain begins, or just as it starts to fall - the truck not even having time to get wet. We had a few days with wild sun-pour-sun-shower swings and its like clockwork - just as it is about to pour, my motor cant hardly idle. Shortly after the sun comes out, the condition gets a lot better, although in Seattle it never seems to completely go away.
I assumed that this being an American turbo car, that fuel metering would be done via a MAP sensor principle, which does not care about barometric pressure. However, barometric pressure is the only thing that I can tie to my motor having this problem - I know it sounds crazy! My woman has the same problem - any time its about to rain, she gets headaches and becomes crabby!!! Then my truck starts to **** me off and I become crabby!!!
That said, temperature does not seem the affect the issue - I have had the truck in 21F as well as 70F with same observations. When the motor is warming up (ie, under 170F) the problem is far less prevelent, but still happens. I have checked my air filter and other under-hood components for abnormal moisture and found none. I have also tried to switch modes on the Aptitude box, to no effect.
What the heck is going on with my rig???
Does this truck have a barometric pressure sensor and if so, where is it?
I got my truck a few months ago and this problem is just driving me NUTS!!
Truck: 2004 2500 RAM, 6-spd stick, Cummings TD with about 160k mi.
Mods: Edge Aptitude set to "0" Stock mode.
In general the truck runs great. Passed emissions 2 months ago with no problems. I have put about 4000 miles on it without issue. Drives and pulls like a freight train.
The problem is during idling. When the problem began, I thought it was some sort of idle economy mode that was not working properly. After a few seconds or minutes of idling (like when sitting at a light), the engine would just sutumble, the computer would try to save it by surging it, but most of the time it would just die. I have had it before when I leave the truck idling and it will idle just fine for 5+ minutes, then the problem starts for no reason - the engine starts to surge and sometimes dies. Other times it gets so bad that the motor dies between gear shifts! Let me tell ya, having your power steering and brakes fade by 90% when coasting around a downhill corner in a 8500lbs truck, is not fun!
When outside the truck I can hear what sounds like a relay clicking coming from under the hood when this is happening, but this may be normal.
This is where it gets a bit strange. After months of this, I began to notice that the problem gets MUCH worse when it rains. I live in Seattle, so it almost always rains, but on a recent trip to Boise the problem went away completely for 4 days, until one day in Boise it rained and the truck started doing the same thing. The following 6 days were sunny and the problem went away again. A day after I got to Seattle, it started again.
I suspected that something - maybe the air filter, a sensor, or some relay was getting wet and causing a problem.
Here is where it gets REALLY strange. Upon further obervation, I noticed that the problem really starts just before the rain begins, or just as it starts to fall - the truck not even having time to get wet. We had a few days with wild sun-pour-sun-shower swings and its like clockwork - just as it is about to pour, my motor cant hardly idle. Shortly after the sun comes out, the condition gets a lot better, although in Seattle it never seems to completely go away.
I assumed that this being an American turbo car, that fuel metering would be done via a MAP sensor principle, which does not care about barometric pressure. However, barometric pressure is the only thing that I can tie to my motor having this problem - I know it sounds crazy! My woman has the same problem - any time its about to rain, she gets headaches and becomes crabby!!! Then my truck starts to **** me off and I become crabby!!!
That said, temperature does not seem the affect the issue - I have had the truck in 21F as well as 70F with same observations. When the motor is warming up (ie, under 170F) the problem is far less prevelent, but still happens. I have checked my air filter and other under-hood components for abnormal moisture and found none. I have also tried to switch modes on the Aptitude box, to no effect.
What the heck is going on with my rig???
Does this truck have a barometric pressure sensor and if so, where is it?
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Joined: May 2008
Posts: 9,657
Likes: 24
From: Louisville, Ky
Welcome to the forum. I have not had any personal dealing with the Cummins, so I do not know if it uses a MAF and BAP sensor or just a map for tuning.
You can download the 2004 service manual for free here and it might guide you in the right direction.
https://dodgeforum.com/forum/3rd-gen...-download.html
You can download the 2004 service manual for free here and it might guide you in the right direction.
https://dodgeforum.com/forum/3rd-gen...-download.html
Thread Starter
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Amateur
Joined: Mar 2011
Posts: 30
Likes: 1
I dont have an OBD2 reader at my disposal to read codes. I dont have any abnormal dash lights.
Per the MAP sensor, found this today, took it out and looked at it. Seemed dirty, so I gave it a good cleaning with Simple Green and conditioned the O-ring there too.
Thing I found interesting is that my Edge Aptitude has a display for barometric air pressure. If the truck uses a MAP sensor, what on earth does it need to know the pressure of the atmospehere - this is completely irrelevant!
Nontheless, I compared the output to my barometer and found that the two did not agree, but were not too far apart. I will monitor this to see if maybe it goes out of whack only some times and not others. I really hope that the MAP sensor cleaning will do the trick... Next step I guess would be to throw an analog pressure gauge into the mix and compare it to the MAP sensor readings. Any other ideas? Could my injectors be a bit a clogged and not spraying well at low RPMs? But how would that explain the problem being so intermitent...
Truck died again today going around a corner out of gear. Really un-nerving when that happens!
Per the MAP sensor, found this today, took it out and looked at it. Seemed dirty, so I gave it a good cleaning with Simple Green and conditioned the O-ring there too.
Thing I found interesting is that my Edge Aptitude has a display for barometric air pressure. If the truck uses a MAP sensor, what on earth does it need to know the pressure of the atmospehere - this is completely irrelevant!
Nontheless, I compared the output to my barometer and found that the two did not agree, but were not too far apart. I will monitor this to see if maybe it goes out of whack only some times and not others. I really hope that the MAP sensor cleaning will do the trick... Next step I guess would be to throw an analog pressure gauge into the mix and compare it to the MAP sensor readings. Any other ideas? Could my injectors be a bit a clogged and not spraying well at low RPMs? But how would that explain the problem being so intermitent...
Truck died again today going around a corner out of gear. Really un-nerving when that happens!
Last edited by Tyson0317; May 5, 2011 at 03:59 AM.