10/5/2023 0 Comments Dodge variable valve timing![]() Three, during the tuning process we adjust things such as our fueling, ignition, throttle controls, and more. Now, we can phase that camshaft both ways, giving us the option to decide and find out what is best for the application during the tuning process. In higher RPM’s, it might be beneficial to retard the mechanical timing to get better HP.Ī time not too long ago, we could get one or the other, retarding the camshaft, or advancing it, so we only got one benefit: better TQ or better HP. At certain times the vehicle could benefit from advancing the camshaft to create higher TQ numbers. Thus, giving us the option to 'phase' the cam for our own power benefits. So, now the camshaft has the option to advance or retard the mechanical timing. The VVT Phaser replaces a simple camshaft sprocket. Two, VVT controls the camshaft(s) in internal combustion engines. A series of mechanical and hydraulic pieces tailored with solenoids controlled by the PCM takes care of this action. There are all kinds of versions and ways to do this, dating back into the ’80s on Asian vehicles. One, what is Variable Valve Timing? VVT is a process many manufacturers use in their internal combustion engines to improve emissions, fuel economy, and power output. Of course, the number one being more power! All is great, but what about that cam phaser thing? What is it? What does it do? How can you use it to your advantage? When Dodge started utilizing Variable Valve Timing (VVT), it was for various good reasons, and during our tuning process, we can use that for our own good reasons, too. Note, the engine may stall during this test.You're ready to tune your Hemi, or you already have your Hemi tuned. Thus movement equates to approximately 30 degrees of crankshaft rotation. The waveform below, image 5, shows the change in camshaft position when the variable valve timing solenoid is supplied with a constant live. It must be noted that the solenoid valve has a constant ground and is controlled on the positive side. The table below shows the signal being displayed on each channel:įrom the waveform above we can see the variable valve timing solenoid valve has a low duty cycle, approximately 10% actuation. Image 4 shows the expecting waveform with the engine idling. This test can be used to inspect the valve timing as well as detecting issues with cylinder sealing. Which is key to testing the dynamic valve timing of the engine.Ī pressure transducer can be used to analyze the in-cylinder conditions with the engine running. The waveform can be used to validate the operation of the entire variable valve timing circuit, not only electrically but also mechanically and hydraulically. The waveform, Image 3 below, shows the same trace during the actuator test. The phonic wheel for detecting the crankshaft speed and position has 34 teeth with two missing teeth to indicate crankshaft position with respect to Top Dead Center (TDC). With the engine at operating temperature and the engine idling, the ignition advance angle will be approximately 6 to 8° of crank angle rotation before Top Dead Center. The ignition coil trace is used as a trigger to capture the waveform and to reference cylinder position. ![]() The table below shows the signal being displayed on each channel:ġ-Yellow-Ignition coil cylinder 1 control Image 2 presents a waveform that shows a trace at idle with 0 percent actuation of the exhaust solenoid. Using an oscilloscope the technician can view the actual change in camshaft position with respect to the crankshaft and the camshaft which hasn’t been actuated. ![]() See image 1 below:ĭuring actuation of the solenoid valve it can be seen that the engine speed dropped to 587 revolutions per minute (RPM), the electronic throttle control system increased the engine speed to prevent a stall so the engine speed increased to 812 RPM before stabilizing at 737 RPM when the actuator test finished. During the functional test, the technician is presented with data. For the purpose of this article the exhaust camshaft timing control solenoid has been actuated. This particular Toyota Auris (Corolla) with a 1NR-FE engine has variable valve timing on both intake and exhaust camshafts. To demonstrate let’s take a look at an example. Using an actuator test, a technician can actuate a variable valve timing solenoid and observe a change in the audible note of the engine and/or a change in engine speed. By altering when the valves open and close you can optimize the performance of the engine. The purpose of variable valve timing (VVT) is to help increase the engine’s volumetric efficiency and limit the exhaust gasses produced by the vehicle. Such conditions can be difficult to diagnose without the correct equipment. Sometimes a vehicle will suffer from driveability issues and fault codes relating to valve timing.
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