Domore Posted October 2, 2014 Share Posted October 2, 2014 Hi everyone, new to the forum. Was searhing the net for answers and found this place. Looks very interesting, lots of information here.Did a search but can't find where anyone else had this problem..Bought a Mack plow/dump truck with a E7 427 motor. 2003 model.Problem is when starting off in any low gear the truck will surge and buck. If you try a high gear it seems okay.A friend believes its the jake brake and it's not completly off. How could I disconnect the jake brake? I really don't have a need for it.Thanks in advance. Quote Link to comment https://www.bigmacktrucks.com/topic/37246-truck-surge/ Share on other sites More sharing options...
mackrmodel686st Posted October 16, 2014 Share Posted October 16, 2014 I doubt its the jake as it doesnt function under 800 rpm or when you are on the throttle. The computer takes care of that for you. What rpm does your tach read when it does this. You could be hitting the Rev limiter. Quote Link to comment https://www.bigmacktrucks.com/topic/37246-truck-surge/#findComment-263481 Share on other sites More sharing options...
gearhead204 Posted October 17, 2014 Share Posted October 17, 2014 as said the eng brake will not work at low rpm with hot oil, if your not use to a electronic eng. the $#@%& computer gives the eng throttle when you let the clutch out,as the clutch takes ahold and the eng rpm falls below spec. rpm, the damn computer revs the eng. for you and can cause the problem. to shut the jake off there should be a rocker switch on the dash that will shut it off completely. Quote Link to comment https://www.bigmacktrucks.com/topic/37246-truck-surge/#findComment-263517 Share on other sites More sharing options...
Domore Posted October 18, 2014 Author Share Posted October 18, 2014 Thanks for the replies.It could be the computer. When letting off the clutch if you are not right on the gas it seems to rev and slow causing the truck to lurch and surge. Give it higher rps and it will stop. But you have to be on your toes all through the lower gears, the higher gears seem to be okay.Its had to explan, but when you get used to it, you can over come it. Quote Link to comment https://www.bigmacktrucks.com/topic/37246-truck-surge/#findComment-263582 Share on other sites More sharing options...
mackrmodel686st Posted October 18, 2014 Share Posted October 18, 2014 Have you tried shifting without the clutch? Sometimes trucks get used to being driven a certain way. Don't ask me why this happens, but I've seen with new trucks they run just fine either way at first. But after a while of driving them one way or the other they won't run right if you try to drive it differently. Same goes for using starting fluid, if you use it to much, they won't start without it event when it's hot out. Quote Link to comment https://www.bigmacktrucks.com/topic/37246-truck-surge/#findComment-263652 Share on other sites More sharing options...
Domore Posted October 18, 2014 Author Share Posted October 18, 2014 Yes we only use the clutch to start off, after that we shift using rpms. If you are quick enough to get the rpms back up it's ok, too slow and it'll surge and buck. We are used to it not and it's not too bad. Quote Link to comment https://www.bigmacktrucks.com/topic/37246-truck-surge/#findComment-263653 Share on other sites More sharing options...
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