1965 Posted December 22, 2015 Share Posted December 22, 2015 SA 0SPN 1127FMI 18Bought this truck & noticed it had hesitation in it in a hard pull; it has gotten worse; it will steady miss at certain RPM sometimes; had conversation on here & probably think injecters need replaced but been trying to get through this peak season to have checked out good & changed if needed; had to go by Mack on ATC issue & talked to mechanic about miss; we road tested & he asked had it had all updates; told him dealer where I bought it was suppose to check & do them; well he said they didn't so he did them; noticed truck did better; noticed it had bout 5 or so lbs more boost seemed to pull harder but still had the miss; he thought could have fuel pressure related; told me to take lines loose at ecm cooler & blow through & check for trash; did & all looked good; truck had just been serviced but I still r&r fuel filters again; ran good for almost whole day; then back to way it was; today it through these codes & I noticed boost pressure back down 5lbs or soAny information would be greatly appreciated Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/43207-2012-engine-code/ Share on other sites More sharing options...
Challenger Posted December 23, 2015 Share Posted December 23, 2015 SPN 1127 Intake Manifold PressureFMI 18 Data valid but below normal operating rangeBasically low boost, its telling you something you already noticed. I would want to know the fuel and boost pressure while road testing. These can be monitored with a laptop. If hesitation occurs and fuel pressure stays the same, but boost drops, it could be the injectors. If hesitation occurs while fuel pressure drops, its probably a fuel restriction. No fuel, no boost. Quote Link to comment https://www.bigmacktrucks.com/topic/43207-2012-engine-code/#findComment-317054 Share on other sites More sharing options...
1965 Posted December 23, 2015 Author Share Posted December 23, 2015 SPN 1127 Intake Manifold PressureFMI 18 Data valid but below normal operating rangeBasically low boost, its telling you something you already noticed. I would want to know the fuel and boost pressure while road testing. These can be monitored with a laptop. If hesitation occurs and fuel pressure stays the same, but boost drops, it could be the injectors. If hesitation occurs while fuel pressure drops, its probably a fuel restriction. No fuel, no boost.Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/43207-2012-engine-code/#findComment-317060 Share on other sites More sharing options...
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