TimberJack Posted May 17, 2019 Share Posted May 17, 2019 2003 427 has a rough idle until engine reaches normal running temp. It’s like it has a slight skip and while idling the truck shakes. Once you run it up to normal temp is smooths out. I’ve just recently installed new injectors and turbo, witch it had the problem before changing. Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/ Share on other sites More sharing options...
Mack Technician Posted May 17, 2019 Share Posted May 17, 2019 I’d check specs on fuel pressure, make sure it’s tuned and run it. There are still engines, like John Deere’s 13.5 liter that still run terrible cold.....in 2019. Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/#findComment-422960 Share on other sites More sharing options...
TimberJack Posted May 17, 2019 Author Share Posted May 17, 2019 I will put a gauge on it this evening an check it. What should the pressure be? Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/#findComment-422970 Share on other sites More sharing options...
Mack Technician Posted May 17, 2019 Share Posted May 17, 2019 50-80 PSI. Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/#findComment-423003 Share on other sites More sharing options...
Mack Technician Posted May 17, 2019 Share Posted May 17, 2019 Google “Mack Service Bulletin SB-224-004” for instruction on testing. Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/#findComment-423004 Share on other sites More sharing options...
TimberJack Posted May 17, 2019 Author Share Posted May 17, 2019 Will do and thanks Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/#findComment-423009 Share on other sites More sharing options...
steeler Posted May 17, 2019 Share Posted May 17, 2019 Could be a crappy eup as well. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/#findComment-423010 Share on other sites More sharing options...
Mack Technician Posted May 18, 2019 Share Posted May 18, 2019 It’ll show itself somewhere down the line. Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/#findComment-423050 Share on other sites More sharing options...
TimberJack Posted May 20, 2019 Author Share Posted May 20, 2019 Is there anyway to test an eup? Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/#findComment-423194 Share on other sites More sharing options...
fjh Posted May 20, 2019 Share Posted May 20, 2019 Bro In my opinion, you can chase this for ever! If the truck is pulling well and not throwing codes just ignore the idle situation ! It could be any number of things ! It may even be the ECM tring to compensate for a minor compression issue! Just be happy your driving a RELIABLE somewhat old school truck and not a new one! Again Just my opinion ! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/#findComment-423198 Share on other sites More sharing options...
steeler Posted May 20, 2019 Share Posted May 20, 2019 52 minutes ago, fjh said: Bro In my opinion, you can chase this for ever! If the truck is pulling well and not throwing codes just ignore the idle situation ! It could be any number of things ! It may even be the ECM tring to compensate for a minor compression issue! Just be happy your driving a RELIABLE somewhat old school truck and not a new one! Again Just my opinion ! I agree. Run it. As far as testing the eup, sometimes you can lay a couple fingers in the injection line and feel the pulse, some may feel stronger/weaker. If you have one that feels noticeably weaker, that could be your problem, but if you're not sure then I would live with it myself. Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/#findComment-423204 Share on other sites More sharing options...
TimberJack Posted May 20, 2019 Author Share Posted May 20, 2019 Ten4, thanks for the info. Truck pulls fine believe I will leave it alone lol. Quote Link to comment https://www.bigmacktrucks.com/topic/57257-rough-idle-while-cold/#findComment-423211 Share on other sites More sharing options...
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