Idling Problems

Just a few more details?

Year, make, model, engine, ,mileage, modifications?

What did you do to get it running again?

Oh, sorry I forgot the most important details! Its an 01 chevy cavalier with low mileage but I'm not exactly sure the number off hand. I changed the oil and filter, transmission filter, air filter and put a new starter in it.

What size is the engine? Are these the things you did to get it running again? Is the check engine light staying on after the engine starts?

This isn't the same "buddy" that drove it into the huge puddle of water that prompted your first request for help, I hope.

No no no he isn't the one that told me it was the coolant temp sensor... although it doesn't sound like that's what could be causing the problems at all so it wouldn't surprise meif he did agree with it lol it seems to be more like the air intake sensor or something along those lines maybe

I would pull any connectors and check for water/moisture. Also, go to friendly big-box auto parts store and borrow OBD code reader and see if I get any clues from that. Coolant temp sensor is a possibility, I suppose, but why would it surge? Also, more likely a bad/shorted/wet connection/ground than sensor, so don't start replacing things wholesale. Also, check for air leak between air flow sensor (assuming it has one) and engine.

I believe your car has a distributor cap.

My first thought would be that the water caused it to crack. This is a common issue with distributor caps when they get wet after being hot.

The next likely fault is the distributor spark plug wires. When they get old they also crack and let moisture in. The same goes for the coil wire.

Next are any electrical connectors that have anything to do with the ignition/spark system.

Also, there is a secondary fuse box under the hood, on the left side in front of the battery. If water got to that it could also drown out the electrical system.

Another possibility is the mass airflow sensor.

Unless you are savvy with auto repair you are heading into deeper and deeper water at this point. You may want to just take it to a garage for repair.

in my opinion it need to be taken to the garage so that all parts which are effected by water or moisture may be located.

It could be one of several sensors. First I would spray the all wires and connectors down with some penetrating oil like WD40. It will displace the moisture. Then let it dry for awhile.

The MAF, Oxygen or Throttle Position sensors any one of these could cause these symptoms.

Take a good look at the Oxygen Sensor. It gets hot, cold water splashed on it could have cracked the ceramics.

could be throttle position sensor. I had my dodge caravan thought the brakes were catching, changed everything and was driving down the road it would drop down to low gear then up again then down. took to autozone they scanned it was a 21 dollar throttle position sensor. perhaps wires got wet and caused it to malfunction. take it to an auto store, most will scan it for you free.

A galloping idle (especially when cold) is a classic symptom of a bad O2 sensor or connection to it.

Easy to tell. Just pull the connector to the O2 sensor and if it runs normally you have a bad sensor.

Just a query here since my familiarity with O2 sensors is less than authoritative.... Do O2 sensors never fail to an open (or predominantly open but intermittent contact) circuit state?

The reason I'm asking is because it seems like if it failed to an open or mostly open circuit state, simply disconnecting the sensor might not result in normal operation, creating a false assumption that the sensor was still good...

?

But that is all conjecture. Care to fill me in on what I am missing?

My understanding is when the ECU sees an open circuit it goes into a limp along mode where the engine runs rich, but will drive normally. You may only notice the difference at the pump, :)

OK. so you don't know the O2 sensor is good, but you would know that it wasn't causing this problem... That makes sense, Thank you.

An O² sensor sends out a specific voltage signal based on the oxygen content it sees in the exhaust system at that point. It would normally vary up or down a few tenths of a volt during normal operation ,once it is heated sufficiently to start the sensor working. If the sensor on the car is the problem, disconnecting it would not be sending the same signal to the ECM. So disconnecting is still a viable diagnostic tool.

Seems like there is a lack of congruence between comment #13 and and your comment (#20)

I think we are all agreeing on the ability to use the O² sensor to determine if that is the cause of the OP's problem. I just seem to have a hard time with my communication skills.

Before getting into replacement parts, look for the water in the high voltage parts of the ignition system. The 1.5 to 2 engine speed is way too high for the car. If the car backfired while trying to start, it may have blown off a vacuum hose. The additional air from this would cause a higher engine speed. I would listen for a whistling sound from under the hood, in the area of the intake manifold. Good luck.

"I would listen for a whistling sound from under the hood..."

That could be me!

If it is, please get your foot out of the throttle linkage.