I have a 2013 Columbia glider with 12.7 Detroit ddec4 with 310000 miles and it will quite often start idling rough and feel rough at low rpms in the lower gears. Once the rpms come up it seems to smooth out and I really don't notice it. I had my mechanic ride with me and do a injector cut out test. It passed the first time then failed then passed then failed again but each time it failed it showed different results so he could not isolate the problem. He said it needs to get worse so he can tell what injector to replace if that's in fact what it is. So far it's not getting worse but is just enough to be very aggravating. Has anyone had this problem before? Would it be a good idea to pull the ecm off when I go on vacation and send it to Pittsburg Power and have them test it out?
low rpm miss
Discussion in 'Freightliner Forum' started by jim3029, May 3, 2015.
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If I were going to send it, I would send it anywhere other than PP due to the recent blowup of that KR truck.
I don't know anything about this shop but it may be worth a phone call... http://oldtunerguy.com/home.php -
You need a new mechanic, the injector cutout would have told you which cylinder. I would find cylinder move injector and see if it follows to new cylinder before doing anything else. If it follows it is injector if not then it will be wiring or doubtful but possible ecm problem.
magoo68 Thanks this. -
X2 on possible ECM issue a lot of 12.7's developed that miss which really didn't affect power or fuel economy much .. Something to do with low voltage or ECM battery getting weak is what they suspected... Best bet is to hang a known good ECM on it and test drive then you narrow down possibilities PS I drove one with that miss for 3 yrs till I switched trucks wasn't affecting much just annoying was all
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Yes most trucks have electronic and electrical problem but you still have to back to basics.
If it is hesitation is at the start I would look at a pressure problem on the pump and maybe a line or exhaust or air intake system may be restricted in some way.
Check all filters and fuel pressure.
If you muffler has not been replaced in a while I would suspect it could starting to plug up.Last edited: May 4, 2015
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Thanks guys. These are all great answers and gives me several things to try. I just ran 700 miles, 16000# up and empty on the way back and got 7.7 mpg so I really can't say it's running terrible but it just never used to do this and it is annoying. Thanks again for taking the time to help.
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Just drove truck back from the shop and it ran great. Apparently oil seeped down the wiring harness for the injectors and into the connector. They replaced the wiring the harness and that seemed to solve the problem.
magoo68 Thanks this. -
i'd try swapping in a new injector harness and see if problem persist
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