Bigger Battery?

[MisterT]

I replaced my stock battery with a dry cell one several months ago and had no problems up until now. My RPMs started dropping to below 500 when in neutral and after the car had been driven for at least 30 minutes, it would drop below 500, shake a little (as if it was trying to stall out), and then the RPMs would shoot back up a couple of hundred and be fine. The dealership thought initially it was the throttle body that was dirty, but after talking to them on the phone, they claim that the computer wasn't adjusted to the newer battery and that they had to reset the computer to correct the problem. Cost? $85 freakin' dollars for 2 seconds of work. Probably their diagnostic charge.

 

[MisterT]

Doesn't sound right. I probably got ***** at the dealership.

 

[Junior]

I'm assuming it's fixed now?

 

[peepsalot]

So resetting the ECU fixed the problem? Doesn't make sense to me. When you swapped out the battery, that should have automatically reset it anyways.

 

[Junior]

So resetting the ECU fixed the problem? Doesn't make sense to me. When you swapped out the battery, that should have automatically reset it anyways.

Interesting ...

 

[peepsalot]

Actually, I'll argue with myself here, it is possible that the removing the battery didn't reset the ECU since it stores settings in memory for some time after battery removal. That's why you are supposed to tap the brakes to properly reset the ECU, to drain out any stored energy.

So, yeah, it's hard to say if swapping the battery would reset the ECU, but I woudln't think a slightly different voltage would affect idling anyways. Battery voltages fluctuate all the time during normal driving conditions.

 

[MisterT]

I'm assuming it's fixed now?

I pick it up this afternoon. I just don't understand why the RPMs would do that now when I had the bigger battery in for months and didn't have any problems! The car is out of warranty as it is a 2001, so it is not like they are trying to get me for something not covered under warr. (mswerd)

 

[Junior]

i was curious since just last week, I swapped out the my stock battery for an Optima... thought it might have been a common problem, but I see now it was just you... lol

 

[peepsalot]

Hope it really fixes your problem for you, bu tI am skeptical.

90% of idling problems I have seen on this board(and some I experenced myself) were due to vacuum leaks.
Many sources exist for vacuum leaks, leaky vacuum hoses, bad seal on your intake manifold gasket, dirty EGR valve.

How many miles on your car?

 

[Junior]

i would have to say EGR valve... most likely

 

[MisterT]

The invoice just says "Re-set base idle. $75 for "lab-mechanical" which is problably diagnostics, and $8.25 for service material. Bastards probably ***** me on something simple.

 

[got wake?]

The invoice just says "Re-set base idle. $75 for "lab-mechanical" which is problably diagnostics, and $8.25 for service material. Bastards probably ***** me on something simple.

sure sounds like it did you try disconnecting the ground from the battery, then tapping the brakes or turning on your headlights to burn up any stored power in the car, then wait like half a minute and reconnect the ground to see if the rpm thing goes away? also, for like 50 starts after resetting the ECU the car will run kind of funny while it remaps everything.

 

[MisterT]

I didn't do that which sucks (something that simple too). This is the battery you got me way back when. I installed it a week after I got it from you and never had any idling problems until now. I wanted to post this so that other newbies would be aware of what to do so that they won't have to spend unnecessary money for the dealership to fix the problem when it is something this simple. Do you have any pics of the Nissan up yet?

 

[MisterT]

I dont think they DC'ed the battery and reconnected because my presets were saved on the head unit. If they did that, I would have to reset every thing. Perhaps this is a good thing as I had my EQ presets saved on my head unit.

 

[got wake?]

I dont think they DC'ed the battery and reconnected because my presets were saved on the head unit. If they did that, I would have to reset every thing. Perhaps this is a good thing as I had my EQ presets saved on my head unit.

they may have reset the ECU another way. i'm sure there is a more in depth way to reprogram it

i'm not done with my nissan yet i was really dragging my ass for a while there cause of all the crap going on in my life. between job, g/f (not anymore), and going back to school, i didn't have time for the truck. but now i waited too long and it won't be done for spring break nationals(chair) ah well, i'd rather not rush it and do it right the first time. i do have an iva-d300 from alpine now, so that rocks

 

[MisterT]

Good luck with all of that Brian. What are you going to school for? I will be qualified for the Radiology Tech program in June, but then have to wait until 2008 do to the waiting list! I talked to some people who are in it and was told that most likely, I will be bumped up to 2007. I also heard that there are a lot of physics courses that I need to take once in the program.

 

[got wake?]

i'm going back for a degree in organizational leadership. that should work out well, cause i go in for an interview this morning for a handgun manufacturer. the owner offered me a job as the facility manager if it goes well, it should be a good pay increase over my current job, plus it'll be a ton more fun, since i'll be in charge of QC and test firing.