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Discussion Starter · #1 ·
Weird... I've had this happen several time: I come to a stop at a stoplight, and maybe 5-10 seconds later, I feel the car jerk forward as if somebody tapped me from behind. I always causes me to look in my mirror to see if somebody hit me. What gives?? I only have 2100 miles. I have an AT.
 

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Discussion Starter · #3 ·
Ah yeah well it's normal then lol. And yeah it does happen w/ my A/C on. Oh well!
 

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it is NOT normal.. it is a known problem without a fix identified. a fix has been ID'd for Lexus and Range Rovers. Waiting for Toyota to implement it on the Toyotas.
Your right, it's not 'normal' on any other vehicle I've driven. But I think what folks are trying to say is ...... that this is normal occurrence on the FJC (and apparently some Tacoma's with the same engine).

DEWFPO
 

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It's not a "transmission jerk" per se, though the transmission does play a role in the issue. The cause is an overzealous application of throttle by the engine to compensate for the accessory torque load introduced by the A/C Compressor and/or engine fan to maintain engine RPM. The application of throttle, whether induced by a change in engine timing or IAC (idle air control), is not quite proportional with the torque loading from the engine components, and because of this it causes the vehicle to surge from the extra power. The role of the transmission isn't really causal, although the stall speed of the torque converter does come into play.

It's a fairly normal occurrence but should be corrected, at least for the 5AT vehicles. I suppose we would have heard a lot more about rear-end accidents caused by this issue if it truly were a major problem.
 

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I have a 5AT that does it and have been told by dealers it's normal.
I like Blackcherryota's explanation though. It does appear to make sense.
It does feel strange when it happens, that's for sure.
 
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