w3grant Posted November 6, 2014 Share Posted November 6, 2014 I have a 2008 Mack with an MP8 in it. Trucks starts up and runs fine then while driving down the road goes into limp mode and wont go above 20mph. A previous mechanic scaned it and said it needed the oil sensor inside the pan they did that and we still have the same problem. That is why I am now looking at it unfortunately I do not have a scan tool so I cant read the data. Any help would be awesome Thanks again! Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/ Share on other sites More sharing options...
j_martell Posted November 7, 2014 Share Posted November 7, 2014 Any warning lights? Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-265866 Share on other sites More sharing options...
wheeler73 Posted November 7, 2014 Share Posted November 7, 2014 Could be a fuel issue also. If you have the stalk switch you can pull codes with it. Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-265873 Share on other sites More sharing options...
Graves Posted November 11, 2014 Share Posted November 11, 2014 (edited) Pop the connector (twist style) off the LHS of the oil pan, if oil made it through you'll be needing the updated oil sender/eop sensor and pigtails. Same goes for the eop, if it's letting oil pass through the sensor, it's fubar. I've done several of these and it requires a jumper harness to be installed between the sensors and engine harness. Edited November 11, 2014 by Graves 1 Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-266391 Share on other sites More sharing options...
Popular Post Superdog Posted November 11, 2014 Popular Post Share Posted November 11, 2014 Everytime I read a post like this I give thanks for my obsolete,outdated,E6 powered Superliner. 4 1 Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-266399 Share on other sites More sharing options...
james j neiweem Posted November 11, 2014 Share Posted November 11, 2014 Right on Superdog Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-266407 Share on other sites More sharing options...
Mackpro Posted November 12, 2014 Share Posted November 12, 2014 Could be air bag dump or power divider solinoid shorting out telling ECM that either is on and limiting road speed. Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-266509 Share on other sites More sharing options...
w3grant Posted November 13, 2014 Author Share Posted November 13, 2014 Ok I will check the sensor in the pan. Where aboust is the eop sensor located? Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-266543 Share on other sites More sharing options...
Graves Posted November 19, 2014 Share Posted November 19, 2014 Right behind the ecm on the right side of the block. There are two but the top sensor is what you're after. You'll know it's bad if oil is making its way out. Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-267242 Share on other sites More sharing options...
Graves Posted November 19, 2014 Share Posted November 19, 2014 Sorry, left side. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-267243 Share on other sites More sharing options...
w3grant Posted December 4, 2014 Author Share Posted December 4, 2014 Thanks to all that helped I found the sensor that was leaking oil.Truck is back up and running. Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-269049 Share on other sites More sharing options...
foxtrot1 Posted June 30, 2015 Share Posted June 30, 2015 Make sure the interlock is not switched on, newer models have this feature enabled to only allow truck to run 15- 20 mph in the event that the switch is on. Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-295084 Share on other sites More sharing options...
Bill P Posted April 23, 2019 Share Posted April 23, 2019 (edited) Have a 2011 Mack Granite with a mp8 engine. When I bought it the one wire on the small fuel filter was not connected but never a problem. Had it serviced today and the tech plugged the wire in and now I have a fault light. Will it go into limp mode? Edited April 23, 2019 by Bill P Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-421217 Share on other sites More sharing options...
c-mac Posted May 7, 2019 Share Posted May 7, 2019 If the regen switch is in the inhibit (down) position it will derate the engine also. Quote Link to comment https://www.bigmacktrucks.com/topic/37639-mp8-goes-into-limp-mode/#findComment-422105 Share on other sites More sharing options...
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