rough idle when motor is warm along with hot weather?

[88rxn/a]

i have a 1995 legacy that seems to idle rough only when it is hot outside? cold mornings it idles great?
i have changed the water temp sensor and ran sea foam into the vac lines and made sure the IAC valve got dosed good also. no codes are being thrown.
any ideas?
also, the timing belt has not been touched for MANY miles and is not due for another 25K miles. it was changed at 100K but im just now hitting 185K. it ran fine up until late this summer. :smt021

**EDIT**
almost forgot,
i changed the fuel filter, plugs and wires a few months back hoping to solve this problem with no luck.

[chuckthefuk]

Which engine? EJ22E or Ej25D

Have you inspected your o2 (oxygen) sensors? You have two (before the cat and after the cat)


If it only runs rough at hot idle, I'd say a bad plug wire or vacuum leak.


Also in the past have you had oil burning or issues with your catalytic converter?

In some cases (since you changed your plugs / wires) the wires come loose at the spark plug and this could cause a miss fire.
Even though you have no check engine lights (CEL) it takes a few passes for the ECU to throw a miss fire code.


If it idles rough, see if you can identify which cylinder or cylinders are misfiring. With the engine running, pull each of the spark plug wires away from the spark plug briefly (don't pull it at the coil unless you want to get shocked). You can also do this by unplugging each fuel injector individually, whichever you would rather do. If you disable the cylinder and the engine speed barely drops or doesn't drop at all, you have identified the misfiring cyl. If none of the cyl is misfiring, you probably have a bad sensor somewhere that is affecting the air/fuel mixture.


-Chuck

[88rxn/a]

Thank so much for the help. i have had the O2 sensor throw a code once in a while. using my scanner i just erase the code and it stays off for a while, then comes on when it feels like it.
Ill try the plug wire thing first though and report back.

Again, thanks!

Btw, it is the ej22 motor

[Dead91silvia]

You can also check you're EGR system. They are known to get plugged up.... but Chuck has got you going in the right direction...

[88rxn/a]

http://www.youtube.com/watch?v=8wEvJNi8 ... ature=plcp (http://www.youtube.com/watch?v=8wEvJNi8a8Y&list=UUsoYcplGV_A6tzGmJP1qeHg&index=1&feature=plcp)

got it to idle like it has been, all plugs did the same (no effect at all) except this one, this one seemed to make it a little worse. when i plugged it back in, the idle seemed fine.

[88rxn/a]

So i exchanged the plug wires and made sure plugs were good. made no difference.
Now im going to order a 02 sensor.

[chuckthefuk]

let us know what happens

[joaks]

My car would idle too fast with warm engine + warm weather. I replaced the TPS with a used one from ebay and has been good as new. Not sure if it is the same problem however.

Maybe clean the MAF also?