I've searched, looked in my Haynes manual, asked the advice of several .org members...still to no avail.

I have a weird idle issue. When I first start my car and the engine is still cold, the car will settle to an idle of about 400. Once it's warmed up, though, it will idle normally at about 650. It doesn't sputter or anything, it just idles at a low RPM (which then causes vibration in the steering wheel and what not). But again, this is only when it's cold...not when it's warmed up. What could cause this? It's driving me nuts...

 

We should make an erratic idle club...I have a vacuum leak from my intake mani gasket that allows my car to occasionally drop to like 200 rpms when the clutch is engaged and engine speed falls; it is not something I'm comfortable with, but have not stalled out yet. At least I finally have mine figured out I guess. Good luck with yours.

 

start with the basic and work up.

clean tb
clean iacv
test tps

 

If any of those were the culprit, why would the problems go away once the engine was warmed up?

 

Were giving you some advise, please try that first and let us know how you make out. You have an idle issue, those are the first steps in correcting it. If that doesn't cure your problem, then we'll look at sensors and such. The can of cleaner costs 4 bucks, sensors are costly. Usually a good cleaning of the idle control components cures simple idle problems. The next order would be testing or replacing the engine coolant temperature sensor. Then there is the cold idle boost plunger which is part of the TB and can't be replaced on it's own, so you'd be looking at putting a new TB on the car. That gets expensive.

Start at the begining and clean the idle control components.

EDIT: I don't think the TPS would cause any cold idle problems.

 

Oh, I will. I apologize if I came off as snobby or anything. I'm just curious, and like to know why people make reccomendations. It's just part of my "I need to know how everything works" attitude

So basically forget the TPS, just clean the IACV and the TB?

 

Been here quite a while ... and actually have never come to a complete understanding why the ECU screw affects the idle .. Try messing with that.. I turn my car on and it idles at 1300, then when warmed is at 900 in neutral, and ~ 750-800 .. but that's because I 'tune' it with the ECU screw.

 

You're kidding me

 

It definitely would. According to the FSM these symptoms of a bad TPS have a high probabillity of showing up:

Engine stall
Hesitation/surging/flat spot
Lack of power/poor acceleration
Rough idle/hunting
Idling vibration
Excessibe fuel consumption

These are the symptoms for an incorrectly adjusted TPS:

Engine stall
High idle/low idle
Slow/no return to idle

 

Nope.. try it and find out or search ...

 

I have a similar problem. There is an adjustment screw for cold starts on the actual TB. I am not talking about the idle adjustment screw on the IACV! People have mentioned you can adjust this to "tune" the cold start idle. The only problem is i have no idea which screw it is! haha. People have told me more than a few times, but every time i ask for a pic, or instructions on HOW to properly adjust it i get no response. Im sure this could be the culprit to your problems as well..

 

Sounds like I may need my TPS adjusted then...but how?
Hmmm...

 

If memory serves me correctly, you shouldn't mess with that screw, but rather follow the Haynes procedure.

adjust your ECU screw.

 

I can take a hint

Do you mean I should tighten it? Or is the potential there for it needing to be loosened up instead?

Also, I'm looking in the Haynes manual...are you referring to the screw that holds the electrical connector in place? (I'm assuming you are...the bracket screws wouldn't make any sense)

 

Just 'do it by feel'.. it's strange and has become a science to me ...

Pm me for details .. because I know there are a few on here that think I'm a wack job .. ...

Try and search some key words idle ECU adjust potentiometer...(I know it doesn't work by this principle but it was still brought up yrs ago)

 

Alright I'm rather sick, but I'll go out and try it here soon...

 

 

Method to adjust the idle in Haynes manual is not correct.
Nissan tech manual has the correct version.
go to http://members.dslextreme.com/users/maxima/esm/
in -ec.pdf

 

Thanks for that, but I don't think I should be messing with adjusting the idle. Setting it higher when it's cold (and low) would result in a higher-than-normal idle once the engine was warmed up, would it not? Not to mention I wouldn't be fixing the problem, merely going around it.

 

Why can't others ever see it this way ... ...

Bobo

 

I know how you feel

 

This is gonna sound crazy, but I think it worked

When I first put it in gear, it dropped to 400...but almost immediately it went back up to a normal idle (~650). I drove it up the street and stopped at a stop sign. The idle then dropped to about 300 I was thinking oh crap, I just made it worse. Well, it went back up again after I sat there for a couple seconds. Never had the problem after that at any point when I stopped. The true test will be the next cold start (I may run out to get a few things in a couple hours). If the problem is gone then, then it did truly work. If not, it was just my imagination.