2005 surging idle only when rolling

[GGranahan]

my 2005 3500 surges from 550 rpm to 900 rpm when i push in the clutch and kick it into neutral only while rolling. it seems to get worse when i brake. as soon as i stop the idle goes to 750rpm and if you rev the motor it will perfectly return to 750rpm. the dealer says they cant do anything til the check engine light comes on. my truck only has 900 miles on it and it is 10 months old , i hate driving it like this , sometimes it almost stalls out.

3500 is a manual trans. diesel xcab



also have 2 other trucks which do NOT do this!

1996 3500 Dual Wheel Cummins Diesel 4X4 Manual Trans Xcab

1999 2500 Cummins Diesel 4X4 Manual Trans



My old 1991 W350 4X4 Diesel Auto Trans never did this either.



How do we make Chrysler aware of this problem and get some action? Just based on these replies in just 12 hours, seems like this is an issue that needs correction asap... . according to the dealer not enough people have complained yet.



I can't believe that I purchased a $40,000 truck that is supposed to be superior to my '96 and '99 models and it fluctuates rpms like a yo-yo. Oo.

I am suspicious that the computer is programmed for a automatic trans that has a constant load on the system rather than a manual trans. Of course, this probably happened on the factory line--maybe not enough manual trans being mfg. or a Friday afternoon breaktime scheduled.



Is there just one ECM program for all trucks or is there a different one for a manual trans and an automatic trans?

 

[nickleinonen]

i doubt it will ever stall out, and 550 sounds a little low for the engine surging, but it is a somewhat normal quirk with the ecm programing. it should stop surging below 15mph i believe, but above that, it will go up and down quite a bit. it has to do with the ecm trying to find out if the transmission is in gear. mine does it too if i throw it into neutral while coming to a stop, but i downshift 99% of the time down to 3rd and at around 900-1000 rpm i go to neutral from 3rd. . at that point, the vehicle speed is below where the ecm won't think it is odd to have the engine idling at

 

[JCleary]

Mine will surge a bit when rolling at speed in neutral as well. I found that applying the brake helps a bit. I really notice it if I run hard through 2 and third, and go to neutral instead of 4th. It's like the computer is expecting a shift and doesn't get it, and the motor surges a bit.

 

[67guzzler]

my 2005 3500 surges from 550 rpm to 900 rpm when i push in the clutch and kick it into neutral only while rolling. it seems to get worse when i brake. as soon as i stop the idle goes to 750rpm and if you rev the motor it will perfectly return to 750rpm. the dealer says they cant do anything til the check engine light comes on. my truck only has 900 miles on it and it is 10 months old , i hate driving it like this , sometimes it almost stalls out.

If it's what I'm thinking of, mine does it. But if I go the exact same speed and coast, the rpm's will stabilize.



Try this. Go 40 mph. Then go into neutral and take your foot off the accelerator all at once. The rpm's will bounce down to around 550 and then should settle around 750 if you keep coasting the same speed. Then brake fairly quickly in neutral. You'll see the RPM's bounce between 550 and 900.



My guess is that the computer is programmed to bounce the rpm's lower than 750 in a not-so-subtle fasion on deceleration. Maybe this serves some purpose for automatic transmission models? I don't know.



If what you're describing is the same as this, I'm not worrying about it. If it's something more, I'd investigate further -- maybe talk to another dealer.

 

[OT-OF-HERE!!]

Surging on idle roll

my 2005 3500 surges from 550 rpm to 900 rpm when i push in the clutch and kick it into neutral only while rolling. it seems to get worse when i brake. as soon as i stop the idle goes to 750rpm and if you rev the motor it will perfectly return to 750rpm. the dealer says they cant do anything til the check engine light comes on. my truck only has 900 miles on it and it is 10 months old , i hate driving it like this , sometimes it almost stalls out.

When mine did that it was the beginning of my injector problems. Leave your truck outside overnight so you can see the exhaust clearly in the morning light and when you start it up see if you've got any white smoke on startup. If you leave it sit a couple days and start it up if you have more white smoke you can bet you have injector problems.

 

[CoastyAV8R]

Mine has done the surging thing since it was new, 28,000 miles ago. I talked with the dealer about it and he even reflashed the ECM and it still does it. I'm use to it now and consider it a normal function of the truck's ECM. My 01 ETH with the 6 speed didn't do this so it was weird when I first saw this one do it.

 

[macdaddy]

completely normal

This has been brought up before. You can do a search if you like.



In short the ECM gets confused trying to find an idle while still receiving a signal from the speed sensor.



Completely normal.



Mac

 

[GGranahan]

Thanks for your reply. Please review my post again... . I have updated it this morning. Seems like your situation is identical to mine. I'd like to get your "take" on the updated post questions too! Many thanks. Greg

 

[robert4570]

Thats the first peculiar thing I noticed about the truck . I was used to the 2 gen which would idle perfect no matter what .

Not concerned , all th 05's I've driven w 6spd do it.

 

[67guzzler]

Thanks for your reply. Please review my post again... . I have updated it this morning. Seems like your situation is identical to mine. I'd like to get your "take" on the updated post questions too! Many thanks. Greg

Greg,



Some things bother some people more than others. This particular characteristic doesn't bother me in the least. I see it bounce down to 550 rpm's, feel the momentary vibration, then feel the computer correct and see it bounce back up. I can almost promise you that it's not going to stall.



This reminds me of the temperature gauge bounce on the 96 model I had. People were up in arms. I loved it. The temp gauge would go up to 1/2 way, the thermostat would open and then it would bounce down to 1/4. Then it would go back up to 1/2 way and then back down to a 1/3 and then continue between 1/3 and 1/2 back and forth. On hot days or under heavy loads, the thermostat would just stay open and it would settle in at about 2/5. Then I bought a 1997 model and it didn't do it. I kinda missed it. Apparently too many people complained about this behavior.



I don't think I'll be going in to complain about this characteristic as it doesn't bother me but I can 100% understand how you feel. I still miss my bouncing thermostat tho.