(2004, Base 350Z) Ok, here's the deal. I was washing my car the other day and got the engine wet. Well a couple days later my battery started dying. It was a 4 year old battery so that was no surprise to me. Well, after I changed the battery the car ran just fine. I drove to the store and when I came back out the engine would start just fine but then the RPM's would just slowly drop until the engine shuts off. It wasn't a violent shut off; it was like the engine just fell asleep. If I gave it a little gas and kept the RPM's up it would stay on and run just fine (but idle very low). The next day I come out and it starts up and runs just like normal. Later that day it was back to dying again. Now it's about 50/50 between running normal and dying. I know when you replace the battery the mapping has to relearn itself, but it shouldn't run fine one time and die the next. Can anyone help me! There are no check engine lights that come on. Thanks for the help

 

Are the battery leads corroded? Have you checked the alternator?

 

Maybe you have a couple of cracked spark plugs.

 

The leads are in perfect condition. I haven't checked the alternator but the battery seems the charge just fine so my guess wouldn't be the alternator. I think it all came from getting wet. I think whatever accelerated the battery's sudden death also is causing this other problem. It starts up just fine so it's not like it's struggling to start. Once I get a "good start" she runs like a champ. How would a spark plug get cracked? Could the water on the hot engine cause that? But like I said, 50% of the time it starts and runs like normal so I would guess it's not a spark plug because it would do it every time if so. My guess is some electrical part is wet or has a bad connection. I just don't know.... Fuses?

 

How 'wet' did you get the engine? Did you start it after it got wet? Almost sounds (to me) like the idle speed sensor is going out. Let's have someone with a more expertise w/ these cars than me give a second opinion, though.

 

An idol speed sensor sounds about like what the problem would be! I don't know anything about that, but it sure sounds about like it. Anyone know about these?

 

I don't recall seeing an "idle speed sensor" on the Z anywhere...

 

I've been looking in the service manual and the things it list are:

PCV (Positive crankcase ventilation)

Electric throttle control actuator <-- My Guess

Intake air leak

I went out and disconnected the ELECTRIC THROTTLE CONTROL ACTUATOR and it started up properly 4 times in a row.... Makes it wonder if water got inside there and is causing problems.... or it is dying... I'm going to drive it home tonight and see what I get...

 

The problem didn't go away with unplugging the electronic throttle control so I'm back to square one...

 

it seems like you got the throttle a little too wet!

 

Damn electronics on cars these days... I guess the Z has newer tech than the old POS DD cars I've gone through. Haven't wrenched on the Z personally (warranty FTW), so I didn't know that it doesn't have something as basic as a idle speed sensor. How does the computer keep the idle speed constant, then?

BTW, although I may have had the exact part wrong, I'm patting myself on the back for narrowing down the problem.

 

Do you feel pretty confident that is the problem? I really want to start narrowing it down....

 

I had an alternator go bad on a car once and it did the slow dying thing while the battery got the life sucked out of it, but when it was done, it was done, no amount of throttle pushing would bring it back to life.

 

Yeah, I had an alternator go out on my 240Z. This isn't similar to that at all.

 

Sounds more like you got the air filter wet to me. If you have an oiled filter you might also have gotten some oil and/or moisture on the MAF. I'd suggest cleaning it with some MAF cleaner from an auto store. Also make sure your air filter is completely dry. Take it out of the car and let it air dry on the driveway or something out of direct sunlight.

The key here is that you were washing the car. This has happened to be before but it cleared up within a few days. Good luck.

As far as the battery that's a little weird to me but whatever, it was old. I don't think it's a related problem.

 

the electronic throttle acts as the iac,but if the etc is wet or shorted it will go stupid and not know whats happening ,it's also going to default to closed as a factory safety

 

I just want to thank everyone for their suggestions. I'm still having the probelm but I've noticed a few other clues. It seems to start better when the car has been sitting for a while. When I come out in the morning I usually will have a better chance of it starting correctly. I've asked around and some think it could be the computer that controls the idle because they said it sells like it's running rich when it gets a "bad start". Either that or the throttle body is not functioning properly and not telling any air in. Does that help anyone out?

 

MAF sensor damage? make sure when your spraying the engine down next time to stay away from the the side with the battery on it, and avoid your intake system. Sounds to me you have water damage on one of your sensors, or a sopping wet air filter which is doubtful.

 

i have the same exact problem on my 03 base. i talked to tim when he was at west covina nissan and he said that most likely it was the throttle body. like the one guy said "the actuator". the bigger issue is that you have to replace the whole throttle body. take it in before 60k

 

see if one of your buddys will loan you their throttle to swap out for a test, if the problem goes away your question is answered.about fifteen minutes is all it takes to swap.