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1UZ no spark?

Matthew Way

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I have just put a new Toyota 1UZ (V8) engine into my Supra (it had another 1uz before that). And finished wiring it all up with the LEM v4 that was previously on the old engine.

At the moment I am not getting much spark, there will be an intial spark when cranking but nothing after that.
Occasionally when turning off or on power, there will be a spark as well.

I have checked and fixed wiring to Cam and Crank sensors, but could it be a faulty sensor causing this?

Is there a way to test that the 2 channel igniter module is doing what it is supposed to?

Is there something else other than those two sensors that could be preventing the ECU to stop sending  ignition pulses?


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First check is to make sure the battery voltage isn't getting low enough to reset the ECU during cranking.  You will see this on the tuning module as it will go blnk for a while, or PCLink will bring up a warning.  The best check is to crank the motor and look for a stable RPM value (on the tuning module or PCLink).  If this value is not correct then it will either be a crank/cam sensor fault (or wiring fault) or an ECU ground fault.  Make sure the ground wires from the ECU are connected to the engine block.  Also make sure the ignitor ground wire is connected to the engine block.  The only way to test the ignitor is to send it back for testing.  Sometimes those engines (especially a second handd import one) can have water and corrosion problems.  Check the distributor caps are dry inside.  Check the plug tubes are dry and that the spark plugs are good.  Note that those motors have a habit of sticking the injectors shut when they have been dry for a while.

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