LR4 Starting Anomaly

Red Top Engine · Feb 11, 2020

I replaced a flywheel on a non-supercharged LR4 with a supercharged LR4 (original was defective). I assume the flywheels are the same. Now truck won’t start.. did so once but couldn’t replicate. I have fuel in rail, spark, and compression. Timing was triple checked. Engine coolant temp is at the half way mark- even on cold. It’s reading 150c (replacement on way). Has anyone had problems with the coolant sensors that would prohibit the ECU from starting the truck?

TrinidadLR4 · Feb 11, 2020

I am guessing a v6 flywheel has different number of teeth than a v8 one and the sensor that's counting the teeth is now getting an implausible signal and won't let the ECU fire.

Red Top Engine · Feb 12, 2020

I must say that had me worried.. it's not my first stupid mistake and thus I just checked the flexplate part number (LR010766) and verified fitment works from 2010 through 2013. The replacement flexplate came off a 2011 supercharged V8, of which it should work.

TrinidadLR4 · Feb 12, 2020

Oh I see, I thought you were using a v8 flywheel on an AJ126 V6 SC model. Sorry about that. V8 to v8 should work though I'd think, supercharged or not.

Red Top Engine · Feb 18, 2020

OK, found the problem. I had the coolant temperature sensor (in rear) connected to the air manifold connector and vs. versa. Surprised the two connectors are identical to allow for such an error; regardless, lesson learned take your time reconnecting wires.

LR4 Starting Anomaly

Red Top Engine

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TrinidadLR4

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Red Top Engine

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TrinidadLR4

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Red Top Engine

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