Ive been looking into the intake manifold system which often needs repair/replacement on the M112 engines. I performed the usual 100K mile maintenance a with new set of 12 plugs and wires, there are no error codes or check engine lights. But on start-up when cold the engine definitely shakes just as if it were missing on one cylinder. It only lasts until the idle drops and once its warmed up it idles totally smooth as it should around 6 to 700 rpm but on initial start ONLY when cold, its always rough and shakes. Maybe this is just normal for this engine but I dont like it.
I ran a can of techron through with fuel level nearly empty and then added a tank of good costco premium and no help here. Considering the Seafoam treatment as well.
Checked all the air seals carefully around the MAF sensor tube and throttle body and it all looks good. Happy to hear any likely connections to what may need addressed, and the MPG is disappointing, 22 highway and under 20 in town.
10-05-2019, 07:14 PM
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