micktq

Hi all, I have a 88 3.2 that I've had years of driving pleasure with no issues what so ever. Recently it startng hunting for idle when sitting at at stop light. I've check for vacuum leaks, the idle control valve, idle switch, etc.. and everything checked out. The interesting thing is if I remove the oil filler cap, the idle smooths out completely. Has anyone experienced the same problem? And what was the solution?

nj1052

As you are probably aware, removing the oil filler cap normally makes the idle run rough. There is a restrictor in the hose between the oil tank and the filter housing which may be blocked with gunge. I suggest the you remove the hose completely and clean it out together with the restrictor. Good luck!

BER

Two potential issues come to mind. 1) You probably have another air leak since you idle actually gets better when oil cap removed. Also, check for the hose restrictor as noted by nj1052. 2) You could have a problem with you idle stabilizer valve (ISV). At the very least, I would pull it off the car and clean the interior with Throttle Body Spray Cleaner. Also clean the electrical connector with DeoxiT. There are other posts that tell you how to test it's proper operation.

Good luck.

micktq

I did check ISV and I seems to operate correctly. I'll check for blockage in the hose. Thanks for your help.

n8kruger

I had a cracked hose give a vacuum leak and cause similar behavior. I don't remember exactly what the hose was but the location was near the oil filter. Flexing the hose displaye the cracks and replacement was simple.