1999 TL 3.2L has had for a long time a quite rough idle. It is NOT the idle that characterized the car for most of its life. When it is very hot (and the engine is hot from several stop and gos), the car will initially start (roughly) but as soon as you put it in reverse to back out of a parking place, the engine dies. It will restart after a few minutes.

The engine mounts are new, the air control valve is new. We have not been successful finding a mechanic that will take the time to duplicate the conditions, so we usually hear, "couldn't duplicate, idle isn't terrible, its an old car."

Anyone have any ideas? Thanks.

 

Yeah, check your EVAP valve for leaking. EVAP valve (under the hood by the firewall on driver's side) opens when the car starts to use engine vacuum to draw vapors from the charcoal canister in the back by the tank. When hot, the valve may not be sealing properly, allowing additional vapor to get drawn in to the intake valve. The car runs rough like it's 'flooded' from the old carburetor days, The valves are cheap, can be replaced with a pair of small pliers (hose clamps) and done w/o getting dirty. Of course, take the old valve off. If you can blow through it, then you have your problem part. Like ny internet advice, YMMV, but this has happened on my 2003 as well as 06 Miata and other cars.

 

Is this the part? https://www.napaonline.com/en/p/NOE911141

 

OEM is cheaper

https://www.oemacuraparts.com/oem-pa...ly-36160p8ea02

find the valve under the hood and test it first.

 

EVAP purge solenoid (on this guy's 2000, and my 03) is right up against the firewall. Yours I likely there too. Remove and try to blow thru it. Ideally, a vacuum hand pump should be used to see if it holds a vacuum. If it's leaking it failed. A hot motor on a hot day will want to draw fuel vapor in to the engine, giving a stumbling, rough, poor idle, until the condition clears. Often if you fill the tank waaaay up, you can experience this as well if the valve is not stopping the vapors from migrating forward to the engine. Now, to get a real hefty draw of fuel vapor in to the engine. both the valve under the hood has to leak when unpowered, AND the solenoid by the charcoal canister in the rear has to leak too.

The under hood is fast and easy to assess. Pull off the hoses, remove valve from its rubber mount and test. It is a good first - possible final - step given the info you provided.

Cheers

 

could you please update when possible. Thanks