Got a 99 n14 in a W9. Few months ago it started a dead miss every so often. Like you shut the key off and on real fast. At first it would do it once a day, then cpl times a day. Now it'll go 3-4 hours and not do it, then have episodes of doing it 3-4 times a mile. No check engine light, runs fine other than this. Seems like a electrical/wiring problem to me. Any suggestions on where I should start looking? Thanks
N14 dead miss
Discussion in 'Trucks [ Eighteen Wheelers ]' started by Stevekw, Oct 6, 2016.
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First thing I would do is put a restriction gauge in the compucheck fitting on the fuel filter. If it reads zero your sucking air. If it reads close to 9 or 10 you have way too much restriction. Check the fuel warmer behind the ECM they are bad to catch stuff and restrict flow. You can have low flow and maintain good pressure. I'm guessing it happens as you shift into high gear and hit the throttle. N14 is also bad for injector issues. If it's on the mechanical side it won't set a code. Also check all the connections for the two power fuses from the battery box to the ECM
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As always, Wore Out is right on the money. I'd also add that the injector harness can rub on the back corner of the engine (usually where the clamp is), and cause funky things like this.
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It happens off and on, usually does it more when driving into a wind where there's constant throttle. But it's also done it a few times within 15 seconds of starting it up of a morning.
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I have seen a broke injector spring cause similar issue, and it wont show up in the ecm or on injector cutout test
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Ecm cables then check others?
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Check the Pass Thru wires on the Injector Harness.
Check Battery, Starter, ECM Cables and Wiring for any Chafing that could cause a Short. -
Another thing you can try to isolate it down to one cylinder on an N14 is unplug 1 injector at a time on the drivers side of the head you'll see 6 matching plugs very easy to unplug one at a time with the engine running and look for the one that has no effect signalling a dead cylinder.
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Fuel shutoff solenoid and the hot wire to it can cause that too. When you turn the key on should hear it click,with your hand on it,you should feel a thunk at key on. If you leave key on for a few minutes and it gets real hot,it's on it's way out.
HopeOverMope Thanks this. -
Second everything already mentioned, but will add check your grounds. Pay careful attention to the grounds to the ECM. Most likely corrosion inside the shield and/or a broken terminal.
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