So I'm driving my 2002 TL-S (105K) and notice that it jolts a bit when I let off the accelerator, as if I'm driving stick and not disengaging the clutch. When I decelerate, there's more jolting as the car seems to go through the gears - especially noticable at slow speeds. The idle is rather fast, so I pop it in neutral, at which point the car starts revving up and down on its own. Somewhere back there, both the CEL and VSA(!) lights came on.

The dealer tells me they pulled 3 codes: P0505 (idle system problem), P0122 (throttle positioning low input), and VSA-related 83-1 (which they say indicates a bad power control module). They're recommending that the throttle body (TPS+IAC), PCM, and tranny be changed.

After searching on this forum, my symptoms sound like classic IAC issues. So I'm wondering a few things:
1) Are my problems caused by all three things simultaneously going bad (which sounds like a huge coincidence to me)? Or is it just the IAC?
2) If it is the IAC, does it need to be replaced or just cleaned?

Thanks in advance...

 

It does sound like it has an IACV problem, but jolting could be caused by broken motor mounts - or did you mean it suddenly started doing it? If that's the case, it definitely could be the transmission. At 105k miles, I'd demand they replace both PCM and Transmission free of charge. 105k is not acceptable for a $30k Honda-built luxury sedan.

As far as the IACV, perhaps you should let them repair it? From why I understand it is not a serviceable part, and has to be replaced.

 

^^ i second a check on the engine mounts. i had the same symptops and then it got worse to feeling a harsh shift on reverse.

you can either inspect them youself if you know how to or take it to a mech and have him take 2mins to check your mounts ~ tranny mount too!

IACV...idk what that is...

 

Idle Air Control Valve.

 

its not jolting when the car isnt warm is it? 15 min after the initial start up?

 

Thanks for the advice - I'll inquire about the engine mounts.

The "jolting" did start happening all of a sudden, and occurs regardless of the engine temp. It feels like the car is downshifting with a thud as soon as I let off the gas, and the tach does move in a corresponding manner (as its dropping, it bumps up with each thud). So I think the tranny is involved. But I was thinking this might be a result of the throttle control problems causing the tranny to receive mixed/changing signals.