News Technical Service Bulletins

Cam Timing Issues With Buick

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Buick 1

When checking the exhaust cam, with cylinder #4 valves fully open, the reluctor should be flush/parallel to the valve cover gasket surface.

 

This bulletin applies to 2010-2016 Buick LaCrosse and 2013-2017 Verano vehicles equipped with a 2.0L, 2.2L or 2.4L engine. The MIL may be on, with DTC P0016 and/or P0017 set.

Some customers may comment of a Service Engine Soon light being illuminated or a crank-no-start concern. Upon inspection, the afore-mentioned DTCs may be stored. This may be the result of a camshaft reluctor that has moved on the camshaft. The reluctor is a press fit and is not indexed/keyed to the camshaft. An overheat condition may contribute to this concern, causing the reluctor to shift/spin on the camshaft when hot. If the reluctor moves far enough, it can create a crank-no-start condition. On rare occasions, the engine may crank and not run and not set any codes. This could be caused by a camshaft reluctor being spun/shifted or a faulty camshaft position sensor or solenoid. It could also be caused by a faulty mass air flow sensor. 

To check the exhaust cam reluctor position LE5 only, with the exhaust camshaft positioned so that the valves for #4 cylinder are at maximum lift (fully opened valves), the reluctor should be flush/parallel to the rocker cover gasket surface. If the reluctor does not line up correctly, the exhaust camshaft must be replaced.

To check the intake camshaft reluctor position (LE5 only), with the intake camshaft positioned so that the #1 cylinder intake valves are at maximum lift (open), the reluctor should be flush/parallel to the rocker cover gasket surface. If not, replace the intake camshaft.

If the engine crank and does not run and no codes are set, unplug one sensor or solenoid and crank the engine to see if it runs. Plug the sensor or solenoid back in and unplug a different one and crank the engine to see if it starts. Perform this procedure for the intake cam position solenoid, exhaust cam position solenoid, intake cam position sensor, exhaust cam position sensor and the mass air flow sensor.

If the engine cranks and runs with one of the camshaft position solenoids or mass air flow sensor unplugged, then typically that sensor is faulty. If the engine starts and runs with one of the camshaft sensors unplugged, then the camshaft sensor that is unplugged is faulty, or the reluctor has spun.

Buick 2

Checking reluctor position on the intake camshaft.

 

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