rspatola88
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E7 400 Mack, Misfire, seems to Move, need help
in Engine and Transmission
Posted · Edited by rspatola88
Hi, new to Mack and need help
I have a E7 400 Mack with a jaccob Brake set up, here's the story the truck had a head gasket problem that was building coolant pressure that we were adding coolant hopping to get a few more weeks out if it till we had time to get the truck in the shop, then we noticed a lack of power and noticed a misfire it seemed to be cylinder 2 and 3 we checked this by cracking the fuel lines loose one at a time, when removing the valve cover we found cylinder 3 exhaust yoke broken, from there we,
Replaced both heads, gaskets , all 6 injectors , and injector lines , and the one broken yoke, piston's and cylinders seemed fine on visual inspection, adjusted valve timing according to the book and have rechecked since 16 on intake and 24 on exhaust, put all back together there is no more coolant pressure problem to still has a misfire , we checked compression and leak down all seem ok, we tried checking witch cylinder the misfire is from by disconnecting each individual fuel pump wire one at a time and it seems that the misfire jumps around, OHM checked all fuel pump wires seems to be ok , swapped the computer with another truck and other truck ran fine with computer not sure where to go next