Rough Idle - Help Please

2001 ACR · Post by **2001 ACR** » Fri May 15, 2009 3:02 pm

I own an 01 ACR, nearly bone stock, with 130k miles. It's starting to idle rough. It normally idles around 900 rpm, but about once a week, starting last month, the rpm's drop to 550-600 and it acts like it is going to die. Does anyone know what's going on? It might not be a an issue, as it only happens about once a week, but I just want to make sure. It seems to generally happen when I'm on a hill and in neutral...

Post by **occasional demons** » Fri May 15, 2009 4:40 pm

IAC valve may be sticking. Try removing it and cleaning. It has a formed O-ring type gasket, so it should bolt right back w/out too much trouble. Two 10 mm head screws. Maybe spray some penetrating oil in it after the carb cleaner to help lube it/prevent corrosion.

2001 ACR · Post by **2001 ACR** » Fri May 15, 2009 5:14 pm

occasional demons wrote:IAC valve may be sticking. Try removing it and cleaning. It has a formed O-ring type gasket, so it should bolt right back w/out too much trouble. Two 10 mm head screws. Maybe spray some penetrating oil in it after the carb cleaner to help lube it/prevent corrosion.

What does "IAC" stand for, and where is it located exactly?

Post by **occasional demons** » Fri May 15, 2009 5:37 pm

Actually it is IAC, I mis-typed. Idle Air Control Valve. It makes a controlled vacuum leak to let more or less air into the engine intake manifold side of the throttle plate to regulate idle speed.

It is the aluminum piece on your TB.

Disregard the arrows.

2001 ACR · Post by **2001 ACR** » Fri May 15, 2009 6:17 pm

Would a vacuum leak cause what my car is doing by any chance? If so, who tests those?

Post by **occasional demons** » Fri May 15, 2009 9:02 pm

A vacuum leak would cause a higher idle.

2001 ACR · Post by **2001 ACR** » Sat May 16, 2009 2:30 pm

occasional demons wrote:A vacuum leak would cause a higher idle.

Oh, I guess that wouldn't be it then...