Lavernm Posted October 1, 2015 Share Posted October 1, 2015 We have a '13 CHU613 MP8 that has developed an intermittent miss. Just over 166000 mi. on the truck. The driver doesn't think it has been doing an increased number of regens. He said that it doesn't seem to miss quite as bad if he is running on cruise vs running with the accel. pedal. He was watching the % throttle application screen and the miss started in the upper 60 %'s. Said it seemed to get some better if he accelerated more. I changed both fuel filters again just to be sure there wasn't something going on there. The truck has one of those fuel conditioner filters on it and I did find that the last time that filter was changed the gasket from the old filter was still under the new filter. So far no codes have come up. We had the overhead run just to eliminate that as a possibility as well. They didn't find anything off much there. It runs well and pulls strong otherwise. Thoughts anyone? Injectors and cups or faulty acc. pedal? Thanks for any help. Quote Link to comment https://www.bigmacktrucks.com/topic/42018-13-mp8-intermittent-miss/ Share on other sites More sharing options...
Mackpro Posted October 1, 2015 Share Posted October 1, 2015 Probably needs an injector kit. We were doing 1 or 2 a week here but have seems to slowed down now. Usually driver will complain at first of a vibration then as times goes by it gets worse and becomes a miss. No fault codes and usually from 60 to 95% engine load. Some cleared up at 100% engine load. If the EGR system all checks out we replaced the injectors and cups and add the fuel tank air filter kits( very importaint). There are a few different kits out there depending on the actual build date. We always call the Mack Fuel Injector Hotline ( yes that have one) to make sure we get the right kit.injector miss.pdf 1 Quote Link to comment https://www.bigmacktrucks.com/topic/42018-13-mp8-intermittent-miss/#findComment-305772 Share on other sites More sharing options...
Lavernm Posted October 1, 2015 Author Share Posted October 1, 2015 Mackpro68, thanks for the info! Do the new style injectors seem to take care of the problem long term? That is interesting about the tank vent filters. Is dirt going through that the regular filters aren't catching?Thanks again! Quote Link to comment https://www.bigmacktrucks.com/topic/42018-13-mp8-intermittent-miss/#findComment-305798 Share on other sites More sharing options...
Mackpro Posted October 1, 2015 Share Posted October 1, 2015 Yes on the new injectors, they seem to have solved that problem. And yes on dust in the air being drawn in through the fuel tank vents and passing through the filters and eating up the injector needle. The old ETECH style injectors worked on about 3000-4000 PSI of pressure where the MP engine is in the 33,000 PSI range. Only takes a speck of dust to mess one up. Its really bad on a local fleet here that pumps off powered cement. The large amount of dust in the air and the big engine fans on the new trucks stirring it up kept us busy with injector kit installs. There is now air filter kits for the DEF tank vents too. Quote Link to comment https://www.bigmacktrucks.com/topic/42018-13-mp8-intermittent-miss/#findComment-305803 Share on other sites More sharing options...
1965 Posted October 2, 2015 Share Posted October 2, 2015 Are the fuel tank air filter kits a update? Or do I need to put some on my 12 model truck Quote Link to comment https://www.bigmacktrucks.com/topic/42018-13-mp8-intermittent-miss/#findComment-305915 Share on other sites More sharing options...
Mackpro Posted October 2, 2015 Share Posted October 2, 2015 If the trucks under warranty and the injectors fail, the dealer will install the filter kit under warranty. Otherwise if you want it , you gotta pay for it. They are easy to install. Here is the bulletin. On trucks that are in any type of dusty condition at all , we install the one big filter and its works with one or two fuel tanks. For all other trucks we install the small filters that bolt behind the fuel tank. One kit per fuel tank is required.Fuel tankfilter.pdf Quote Link to comment https://www.bigmacktrucks.com/topic/42018-13-mp8-intermittent-miss/#findComment-305918 Share on other sites More sharing options...
Lavernm Posted October 2, 2015 Author Share Posted October 2, 2015 So our truck with the miss would probably not be covered under warranty as the standard engine warranty ran out in April of this year? It would probably be wise to install the tank filter kits on our other identical truck? It is one build unit ahead of the truck with the miss but has a lot less engine hrs. They both pulled dumps with fracing sand before we got them so they had a fair amount of pto time. Quote Link to comment https://www.bigmacktrucks.com/topic/42018-13-mp8-intermittent-miss/#findComment-305926 Share on other sites More sharing options...
Mackpro Posted October 2, 2015 Share Posted October 2, 2015 It wouldn't hurt to put them on. Also when changing your fuel filters. When u fill up your filters before you install them, make sure the fuel your pouring into them is very clean. We have a old MP filter stand mounted on our fuel dolly and small electric pump. The pump pulls the fuel through the filters on the filter stand then out the hose into the new filters to be installed on the truck that we would be servicing. Quote Link to comment https://www.bigmacktrucks.com/topic/42018-13-mp8-intermittent-miss/#findComment-305929 Share on other sites More sharing options...
Lavernm Posted October 2, 2015 Author Share Posted October 2, 2015 Ok, I don't pre-fill the filters, I just use the primer pump. It is kinda slow though.Thanks again. Quote Link to comment https://www.bigmacktrucks.com/topic/42018-13-mp8-intermittent-miss/#findComment-305940 Share on other sites More sharing options...
1965 Posted October 3, 2015 Share Posted October 3, 2015 That's the way I change my filters also; all other new engines want you to put on dry Quote Link to comment https://www.bigmacktrucks.com/topic/42018-13-mp8-intermittent-miss/#findComment-305998 Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.