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GM Informational Bulletin on ENGINE FLARE

1708 Views 2 Replies 3 Participants Last post by  acarney
I posted a thread on a few days ago on what I perceived was the infamous Gen II CHUGGLE. Lots of back and fourth and good info.

But I decided to call the service manager at the dealer I have purchased 3 Volt's from and over 25 other vehicles over the decades.

He found an "Informational Bulletin" not a TSB on something GM calls "ENGINE FLARE" and he read it to me over the phone. It starts with the usual - The customer may complain..... by the end it states it's a NORMAL operational condition on the Gen II Volt and the 5ET50 operating between it's five modes. Of course in between the Customer and Normal Operations were many situations when the anomaly can occur i.e. DRIVING IN LOW, USING PADDLES, STEADY STATE SPEEDS, TEMPERTURE etc.......

So unless it get's worse it seems to be a normal operating condition and I'm willing to leave it at that. Maybe some can find a post a copy of this Informational Bulletin for our edification.
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That particular preliminary bulletin PIC6161 has been around for a while now
I've never really felt the need to post anything about here as its pretty much well established around here that while operating in extended range mode, occasionally the engine RPM of the ICE will "flare" (usually described as a sudden/brief RPM increase).
This occurs during certain transitional periods where the clutches and gear states (modes) within the Volt's transaxle are being reconfigured.
It does this in order to synchronize the speeds of rotational elements during the "shift" (clutch apply/release) whenever commanded, in order to maintain efficiency
and yes, (as often discussed) this is considered normal behavior
I'm wonder how noticeable that is with actual feel of the car, like G forces on it. I can understand the SOUND of the engine suddenly changing might make you feel like it's speeding forward or something, but is it actually producing a G change (either acceleration or deceleration) on the vehicle? Because I'm almost certain my surging/drag would show up as a change in momentum. Something is certainly adding drag to the drivetrain and then removing it... every half second or so. Why would it be designed like that???
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