jweilert Posted December 8, 2009 Share Posted December 8, 2009 new to us 2004 mack vision with the 427 engine, issue is when you let off the throttle seems that the jake brake always come on a little, then when you get back into the throttle, it makes two belching kind of noises and then take back off, almost like it is missing out. Also does not have the power of or 98 427. Any help would be appricated Quote Link to comment https://www.bigmacktrucks.com/topic/11736-2004-ai-427-motor/ Share on other sites More sharing options...
Mackpro Posted December 8, 2009 Share Posted December 8, 2009 new to us 2004 mack vision with the 427 engine, issue is when you let off the throttle seems that the jake brake always come on a little, then when you get back into the throttle, it makes two belching kind of noises and then take back off, almost like it is missing out. Also does not have the power of or 98 427. Any help would be appricated If the engine has the "powerleash" engine brake, the o-rings on the engine brake solinoids could be bad/cut and causing oil leaking into piston area and slightly applying brake. We have seen this before quite often. As far as the low power, read some of the posts on the 460 HP CV's and about going to the dealer to get both ECU's reflashed with the new software for poor throttle responce. Need last 6 of the vin and I can tell you if it need the new software. Quote Link to comment https://www.bigmacktrucks.com/topic/11736-2004-ai-427-motor/#findComment-44827 Share on other sites More sharing options...
Mackpro Posted December 8, 2009 Share Posted December 8, 2009 new to us 2004 mack vision with the 427 engine, issue is when you let off the throttle seems that the jake brake always come on a little, then when you get back into the throttle, it makes two belching kind of noises and then take back off, almost like it is missing out. Also does not have the power of or 98 427. Any help would be appricatedAlso does it have a auto shift or ultrashift trans? If so the engine brake will engage to help the trans shift even if you got the brake turned off. Quote Link to comment https://www.bigmacktrucks.com/topic/11736-2004-ai-427-motor/#findComment-44828 Share on other sites More sharing options...
jweilert Posted December 9, 2009 Author Share Posted December 9, 2009 Also does it have a auto shift or ultrashift trans? If so the engine brake will engage to help the trans shift even if you got the brake turned off.no has a 10 speed, any ideal about what would cause the beleaching and missing when you get back in the throtle Quote Link to comment https://www.bigmacktrucks.com/topic/11736-2004-ai-427-motor/#findComment-44852 Share on other sites More sharing options...
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