my_s2k

Ok. I asked about having this rough idle problem after replacing the dead battery before. At the time I received responses saying it's a known S2K characteristic where after "resetting" ECU, I'd have a rough idle a few times or so and it'd go away. And it did at the time. However, that was easily 6 months ago (it was beginning of the year), and since then I have not touched the battery. It's been replaced with the OEM honda battery.
Now I get rough idle time to time and it just seems to be getting worse. I now experience that on highway where I feel like there's a significant power loss (I keep the throttle the same but the car starts slowing down). Just normal cruising, it was again acting up and my car was jerking as if I was tapping the gas pedal. And for this, this moron in SRT4 thought I was trying to race him and he tried racing me (revving his engine and doing that jerk motion himself!!)
Does anyone know what the hell is wrong??? This can't be normal. I just fire up my car and sometimes I see the RPM just bounce around anywhere from what seems to be 200 (like 1 bar on RPM meter) to 1200rpm.
This just happens randomly and I can't reproduce it. Since my car is 03 with 44k miles, obviously it's out of warranty period and if someone ever had this issue before and could guide me in the right direction, I'd REALLY appreciate it.
I wrote more than I planned but I just really want this issue resolved.
Thanks so much in advance for your help / input.

Chazmo

I'd pull and replace the spark plugs to start. Look at each plug and see if anything looks wrong.

Another thought might be dirty injectors... Try some cleaner added to the fuel.

xviper

Also consider MAP sensor and the way the harness is secured.

Bo_Vien

2months ago, my car had the same hesitation problems at 40K miles on the odometer. I followed the MAP thump protocol and reset my ECU, and the car runs fine now.

my_s2k

Thanks, everyone.

xviper, I looked around the engine bay and I noticed a wire that's not connected to anywhere. I also looked everywhere and I can't find the other end plug!!
Umm.. please tell me that's normal?!?!?
Again, thanks a lot!

The wire is out of where I marked red in the picture.
It's a 3 pin male plug and I can't find the other end (female) plug.

xviper

Did you buy the car used? That appears to be an aftermarket oil pressure sender. It's coming out of where the stock oil pressure sender should be. When you key your ignition to ON, does the oil light on your dash come on till you fire up the engine? Is the stock sender still there? It'll have a rubber boot around the end of it and one wire under it.

my_s2k

Yea I bought the car used. So do you think this is the cause of it?
When I key the ignition to ON, I get "Brake" <- since handbrake's on, "Battery", "oil light", and "EPS". They all stay on.
And I am not sure if the stock sensor is still there. I can't find anything else. I am assuming this stock sensor sould be somewhere near this loose wire?
Also is this plug and play kinda thing? Meaning to replace this with stock sensor, I just plug this out and just put in the stock one?

xviper

No. This likely has nothing to do with your idle situation (if it's an oil pressure sender).

So what happens to the oil light once you've started the engine? If the oil light goes out, then the stock sender has to be there.

Not knowing what you've got going on there, I can't comment on whether or not it's a "plug and play" thing. Since you can't tell me if you have the stock sender there or not, noone can even tell you what to replace or what not to replace.

Chazmo

David,

I think you're saying that a whole bunch of your idiot lights are on. You probably should've mentioned that first. You should tackle this one problem at a time (or bring it to a competent mechanic).

my_s2k

Sorry about the late response, xviper. Been busy with work.
Yes all the lights go off once the engine's turned on.

I will try cleaning out MAF to see if it works. I just put in the fuel system cleaner thing today. Hope this does the magic.