95 camry idleing up and down repeatedly every second, any thoughts?

[dsmith222]

Hi , my 4cyl. 95 camry was running perfect and all of the sudden it does not idle right. It normally idles around 1000 rpm, but it now drops down to 600 and back to 1000 rpm every second, at one second intervals and it does this over and over again. I cant for the life of me figure out what is causing this problem. I thought it might be an air leak in the air intake hose, so I removed it and it still does it with it taken off the throttle body. There doesnt seem to be any hesitation at all when I step on the gas or floor it. The only other thing I noticed is my fuel economy seems to be suffering badly, I havent tracked it yet for MPG but I find the needle falling fast. Any ideas would be greatly appreciated. Thanks alot.

[Hobo]

I had a somewhat similar problem

Sputtering at Idle

[dsmith222]

Finally found out what the problem was, I couldnt take the bad fuel economy,and I was running out of time. I exhaused every option trying to diagnose it myself but turns out it was a broken vaccum line rubber tube that ran to the manifold absolute pressure sensor. I thought I had checked every vaccum line but I overlooked this hose because I thought it was an electrical wire because there is some plastic coiling around it, never thought it was a vaccum line. I was hearing a hissing sound coming from the area but couldnt pinpoint it, it sounded like it was coming from the throttle body which makes sense because that little black box that is the map sensor is located only within a few inches of the throttle body. Boy am I glad to have this fixed, i was getting 8 mpg and with the price of gas it was taking a toll on me financially. The map sensor was running too lean and it was dumping too much fuel into the engine to compensate for the lean condition.