When i first start my car after sitting the idle seems to be rough. Like its misfiring every other second or so. After the car warms up or gets warmer the idle gets better. When it was warmer out the idle seemed to be good just about always too. So i was thinking something metal is the problem. When its cold the metal part is contracted and making less contact, and once it gets warm it expands creating a better connection? just a theory. Maybe its my wires or something simple?

 

Somewhere it is said for older cars should not be "quick started". Which means that the vehicle should not be in motion (Our for some people, in high revs or acceleration) without the Maxima reaching operating temperature. For me, that means just as long as the temp gauge needle is not in the lowest position. One time I stalled my car by quickstarting. I could put it in D without warming it up.

Anyone else have any ideas?

 

I'm not saying this is the problem. When I had that same problem I replaced my air idle control valve.

 

Don't want to derail, but I have the reverse problem. My 93 GXE idles like a dream when it's cold started. When the engine warms up, however, it idles horrible and I think it runs rich because I can smell gas in the exhaust. I swapped out spark plugs, distributer cap and rotor, PCV valve and CTS. Does anybody know what could be up ?

 

In both cases try ECT sensor and IACV

92gxe/cg2 - all your vacuum hoses in good condition and properly connected?

Darkwing48 - I too don't like to use anything near full power (even half is too much imo) on a cold engine and especially old and cold auto box, but there is no real reason not to start moving the vehicle soon as its started - it was made to be able to handle that situation

 

Yes my vacuum hoses are fine, and all that. Ive heard about the ECT (engine coolant temp??) sensor before and would liek to replace mine to see what happens. Where is this sensor at, what does it do that could interfere with the idle and how do i chagne it out? I believe i heard it was a simple sensor u just pull out but dont know for sure. i also highly doubt theres aynthing wrong with my IACV just to put that out there..

 

Its buy the t stat you can't miss it it has a plug going to it I think the plug is yellow.

 

I hope the pics help you out.

 

How hard is the IACV to clean?* Pics would be great

 

Could it also be the EGR temp sensor or is that not likely ?

 

Not hard at all I used brake clean on mine. Just make sure you get the IACV gasket. And as far as the EGR temp sensor I would not think it would be that but I could be wrong.

 

alright, thanks for the pics and info guys, concerting the ECT sensor, what should i do, replace it or clean the connector? or try the latter first...

 

which one is the IACV?

 

 

I had a feeling that was it. I was afraid to pull it off incase there is something that is springloaded or has to go in the exact way it came out.

 

Naw,nothing is going to go flying across the garage when you remove it.

Just be sure to buy new gaskets before you take it apart to clean/replace..

 

So I guess you pull it off and then spray the insides with brake cleaner... Do you have to order the gasket from the factory or can you get it from Autozone or something ?

 

No...Not brake cleaner..Throttle body cleaner..

 

there is more than 1 gasket?

 

no just the one between the intake mainfold and the last third of the IACV assembly. that being the 'air cut valve' portion, middle is 'valve seat and idle screw' portion and the outer part is the 'stepper motor and valve piston'

 

All of the times you have HIGHLY doubted something [I've said] you were wrong. How do you really know your IACV isnt faulty? What makes you think it is functioning properly?

 

john lets get some examples? Like when my plugs rotor and cap were bad, even tho i said they werent, and were they now? no..... lol but back to the IACV

ive read some symptoms of a bad iacv and mine doesnt have said symptoms. Also my idle is always a constant RPM, never fluctuates, slowly lowers itself when going from cold to hot after driven etc....

Im sure its possible to have a faulty IACV even if the idle speed is perfect and never fluctuates but im just doubting that. How would an IACV lead to a misfire too? i probably should clean it because even when theres no misfire and its idling fine u can feel a vibration thru the cabin more like a pulsing.

 

ECT determines mixture quality presented to the cylinder based on temp - the colder the richer in general. If the ECT tells the ECU lies, a lean mixture can be caused, and non-reliable ignition is the result.

If all else seems to be in good nik and working I guess the most basic of causes of this may simply be engine condition.................

Remove and block the crankcase breather hose from the rear valve cover (leave the nipple on the valve cover open) - is there an improvement/change in the symptoms described in your first post?

What are the actual individual WOT cylinder pressures when doing a hot compression test?