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TRIFECTA: 1.4L Turbo Throttle body comparison LE2 to LUJ/LUV

During our tear-down, we decided to take a few moments and compare the throttle body on the LE2 engine to the throttle body on the LUJ/LUV. While they are very similar in size, there are some interesting and noteable differences. The first of which, is how the cold side charge pipe connects with the throttle body. On the LUJ/LUV, it's a barbed inlet with a worm-style clamp. On the LE2, it uses a "quick disconnect" style connector that's similar to the large PCV supply to the intake manifold on the LUJ/LUV.


Charge pipe connection to intake manifold


LE2 and LUJ/LUV Throttle Body

The harness connectors are also different between the two units. Both sport 6 pins, but the LE2 throttle body utilizes a flat connector, whereas the LUJ/LUV throttle body utilizes a rectangular connector.


Harness Connectors (LE2 Left, LUJ/LUV Right)

Aside from the obvious physical differences, we can't actually see the most stunning difference of all. One of the changes GM has incorporated in recent years is the use of a more-reliable one-way serial data protocol (SAE-J2716 Single Edge Nibble Transmission "SENT" protocol) to digitally transmit the position of the redundant throttle position sensors (TPS) 1 and 2 back to the engine control module (ECM). In contrast, the LUJ/LUV uses 5 volt referenced analog/resistive throttle position sensors 1 and 2 to report the position of the throttle blade back to the ECM.

Why switch to SENT? There are many reasons, not the least of which is the SENT protocol defines a checksum scheme that allows the ECM to verify the accuracy of the information being sent from the throttle body. Failures in "drive by wire" throttle control schemes (such as are used on both the LE2 and the LUJ/LUV) are a constant worry and concern of auto manufacturers as they could lead to uncontrolled wide-open-throttle conditions. The predecessor to SENT has redundancy built in by providing two sensors that report opposite voltages, allowing the ECM to perform some level of plausibility checks, but in the event that both sensors are incorrectly reporting the throttle position (but correctly reporting their opposing voltages), the ECM may not be able to detect a throttle control error. SENT helps to alleviate some of these scenarios.

It's an exciting time for automotive technology! Stay tuned as TRIFECTA continues to shed light on emerging automotive technologies!

TRIFECTA SGE Performance Team
 

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Working with the SENT technology on our product. Not sure what micro GM uses, but we are using a Tricore 237LP micro and it supports the SENT protocol. It doesn't have 3 cores as the name suggests, it is just a single core. Since our product isn't as nearly complex as an engine controller, we got a lower end Infineon micro. We also wanted to migrate away from the 16 bit micros, because technology is out growing them and 32 bits micros are becoming less expensive.
We shouldn't even be using a Tricore, we should be using a Power PC core, but our customer DRE misinterpreted a requirement and stated that we needed to support CAN FD. During one of our first post development Q&A meetings with our customer, the CAN experts in the room ask why we had questions about CAN FD when we are designated to be compliant to the CAN 2.0 HS bus. Our team had spend two years developing the global platform base software for the Power PC only to start over and then realize that we didn't need to. The positive is I finally get to work different architecture micro, worked with Power PC and s12x my entire career. Learning something new.
 
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