912 ULS miss

Check that the spark plug boot/connector has not been pulled partially loose from the wire or coil. This can can happen when pulling plug wire off the spark plug when removing plugs without knowing it. A quick check with an ohm meter to check the plug connector, wire and coil should read about 15K ohm in series is to measure in series the top front left to right side, the top back left to right and then do the bottom the same. If the plug connector has been pulled partially off cut the plug wire off about a 1/4" and resemble with dielectric grease.

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Hi Rod,

-- Are you confident that the ignition system is not to blame ?

------ Does the engine miss on single ignition A or B  ?

-- Did you inspect the induction system for any leaks ?

-- How about a borescope inspection to check the valves ? You could also pop off the valve cover and look for any obvious defects.

-- --While performing leak down test spray cylinders with soap and water to inspect for cracks and leaks.

-- Remember to also inspect cylinder 3. The issue may be there even if symptoms show up on cyl 1.

Cheers,

Denis

Hi guys, sorry late reply here.... Thanks for your replies so far. Everything is being considered at the moment and your guidance is much appreciated. Today I have been looking at the coil packs, ignition leads and boots. Resistance of the boots are all in spec between 4.4k and 6.0k ohms. Primary side all in spec between 0.1 and 0.4 ohms. However high voltage side is 5.83k to 5.95k ohms, outside the 6.1 to 6.7. Any thoughts on this?

Thanks heaps 

Rod 

It is unlikely to be ignition, but that is easily determined, as Denis mentioned, by running on one mag only and seeing if the miss continues or goes away.

Then switch to the other mag and repeat the test.

As you have two independent ignition systems, if the problem is truly with the ignition you will be able to isolate the trouble. if the trouble is the same on both the mags the ignition is not faulty.

It is normal for #1 cylinder to be richer at idle, and to a lesser extent #2 cylinder.

For an accurate test run the engine at 5000+ and then check the spark plugs.

Thanks Rob.... I did a cold compression test on Monday and all cylinders were 125 psi... I was going to do as you say but at 3000 rpm but 5k will be better yes, and also a leak down test. Damn virus is holding us up here in Oz at the moment so this might be a slow process.

Thanks heaps 

Rod