96 CX Hatchback. Stock 1.6 L engine. Car sat for awhile, maybe 6mths with only the occasional start/drive. Now engine surges at idle. Surging starts about 3 min after start up. I've replaced the fuel filter thinking maybe water had condensated in the empty fuel tank while sitting so long. No luck, then replaced the MAP sensor today. Still no good. Any advice anyone?[]

 

ignition timing and vacuum leaks.

 

does it have a fpr on it? if so that could have gone bad, i saw a car this weekend and that was his problem

 

What's a FPR and what does it do? Where is it located on the vehicle?
G

 

What's the best way to find a vacuum leak?

 

an fpr is a fuel pressure regulator, i think he means an aftermarket one, so you'd know it if that was the problem. the stock ones on the end of the fuel rail, it doesnt connect to the fuel filter on the firewall, but a small black hose comes out of the bottom of it and runs back under the car to the fuel tank. vacuum leaks are pretty hard to find, look for leaking hoses, ones with cracks or something in them.

 

Okay here's the deal. If I unplug the MAP sensor while the engine is surging, the surging stops. That's why I changed the MAP sensor to begin with. Plug the MAP sensor back in, runs fine. Shut the car off, start again (with the MAP sensor plugged in) the surging starts again. Start with the MAP unplugged, no surging. Once again, its a new sensor and I have power (4-5 V) on two of the three wires for the sensor harness and the third is a good ground according to my mulitmeter. [:@]

 

No FPR that I can see, but thanks for the tip!

 

With the vehicle running, take a can of carb cleaner and spray it around your vacuum hoses. If the idle changes (usually goes up) thats a good place to look. DO NOT spray it around the air intake as it will send you on a wild goose hunt looking for leaks that do not exist. Again the idle will usually go up but it can cause it to drop. Either way, there is an issue at that spot. Cracked, loose end, hard and not sealing, you get the point.

 

Problem solved! Hopefully.[&:] Removed the sensor plugs for the MAP, TPS and everything else I could find and cleaned the connections with an elecrostatic cleaner. Guess maybe a little piece of corrosion formed on one of the connectors while it sat for so long.
Thanks to everybody for the help