Repair-It

Uh oh. https://www.chevymalibuforum.com/thread ... ds.117321/

Circuit/System Description

The intake valve lift control system enables the engine control module (ECM) to change the camshaft lift and duration while the engine is operating. The camshaft has 3 lobes for each intake valve. The inner lobe is for low lift and the 2 outer lobes are for high lift. The rocker arm solenoid valve controls the 2-step lift by controlling the oil flow to the rocker arm. In default mode, a locking pin locks the inner and outer mechanisms of the rocker arm together to provide high lift. When low lift is commanded, oil pressure retracts a locking pin within the rocker arm.

The intake valve lift control system has rocker arm solenoid valves that are controlled by the engine control module (ECM). The rocker arm solenoid valves are supplied ignition voltage and a ground circuit to each solenoid. The ECM operates the rocker arm solenoid valves by controlling the ground circuit to each solenoid in order to control the amount of oil flow and pressure to the switching rocker arms.

I ordered this: https://www.ebay.com/itm/333683952200?_ ... R8jVmpzdZA

New GM OE update oil flow control valve GM#19419980 this replaced the old part 12633613

The Box was opened for pictures only the valve is still sealed in the plastic wrapping

Includes gasket that is required with updated designed valve GM#12634467

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***HAT IS NOT INCLUDED***

Valve and gasket. A little under $150 all in.

Tackled this just now. Pretty straight forward though pulling the intake resonator off is a little more fiddly than I expected. I've done it before, too.

Need to remove the engine cover as the first step. Oil fill cap and 3 torx bolts. The variable valve lift control solenoid is approx in the center of the frame. Just 3 bolts and an electrical connector.

Removed, and compared to the new one. By visual inspection it looks suspect. Labels and things like that. But the old one was only 8g heavier and that was probably just residual oil so that's a good sign. I did an electrical resistance check of the old one and new one. Results indicate a short between one of the coils so that's a smoking gun. Yay. New one installed. Put everything back, reset code and test drove.

Everything seems normal. Laid like 5 feet of rubber flooring it from a stop. The tires are lame but that's something. It runs fine. Long term fuel trims a bit high but it's probably that intake manifold gasket issue. Not going to chase that as I tightened the bolts some time ago (added loctite as well). I'll wait until it gets significantly worse. At idle LTFT peaked at 16% which seems high. When driving it's single digits generally so I'm good.

Also replaced the oil fill cap since the old one was leaking maybe?

A hair under 149k.