gsimba

I need help, my 1990 LS400 with 212K miles just started idling up-down up-down when in park but runs fine in gear but the idle doesn't come down to around 600rpm like before, it stays at around 1K. Any thoughts on what that might be? My mechanic says it's idle control solenoid but I have my doubts

Thanks

GRAND_LS 4

iTrader: (2)

Sounds like your idler valve needs to be cleaned, or replaced. But lets see if anyone had this problem before.

gsimba

I got it fixed today, it was the Idle Air Control (IAC) value for sure. It's black about the size of a small fist..... Had to be replaced.

gsimba

Thanks Grand LS 4 for the advise, very much appreciated......

GRAND_LS 4

iTrader: (2)

Thanks for reporting back. Glad you got it resolved.

NewLSlover

How much did the valve cost? I'm sure it's an easy swap...

mbwtrpolo

Hey, i just had the same thing start happening (the up and down idle while in park or neutral) and I pulled the idle control valve off, cleaned it, reinstalled it, and it continued going up and down. I then pulled it off, removed the other three screws on the idle control valve itself and just pulled it apart to see what it consists of. After turning the magnet and making the valve piece go up and down, I moved it so it was pulled back as far as it would go and reinstalled everything. This time the idle returned to normal and the up-down rev of the engine is gone. I don't know exactly what it did to take it apart and move things around, but it fixed the problem. Anyways, thanks for posting the problem, it gave me a whereabouts of where to look to fix it. By the way, a new idle control valve looks to be around $600.