i just have the tt engine swap done to my Z, but the rpm keep reving up and down during idle after the car warms up, i am not sure if thats the temperature sensor or something else, thanks for ur time!

 

Sticky idle control valve? Spray it with a bit of carb cleaner

 

i am back to my Z again, my 86 RX7 5 speed N/A had the same problem, idle reve up and down 1500 +/- 100 rpm, i had this problem solved by unpluging this plug: http://www.flickr.com/photos/23732694@N03/4561706961/
and i did the same thing to my Z, had all three plugs around the IACV unpluged, still didnt work.
i am goin to clean the IACV soon or later, already checked most of the vaccum hoses, no sight of vaccum leak while we were running a smoke machine.
what else should i look at? TPS?

 

the EGR can cause that problem. possibly temperature sensor as well. it's worth a test/cleaning of the plug.

 

i sort of thought of the temperature sensor, cuz it idles around 1100(sometimes) steady if i dont drive rough.
any way to check if the EGR or temperature sensor are bad?

 

i'm really not sure how to check the egr. i think you'd have to put constant vacuum to the line that runs to the top of the valve to test if that's your problem. maybe even just pinch it.

there is a test for the temp sensor somewhere. they're cheap though so you may as well just buy a new one.

 

i am goin to clean the EGR, both on my RX7 and 300zx, the problem is looks like EGR from 300zx is right against the fire wall, hard to get it out?

 

looks like the EGR and IACV are very hard to reach, are they inbetween the firewall and back of the engine? do i have to remove the throttle body inorder to reach them?

 

you can reach the IACV, but what are you doing to it?

the EGR is fairly untouchable with the plenum on, but you don't need to touch it. like i said, you'll need to look up the procedure for that one. i don't know how to test it.

to take care of the idle control valves, you need to take the hose off the back of the balance tube and blast wd-40 down it. that will clean them out well and might help out. there are a ton of threads about this problem. i've had it and fixed it and i've been thinking about it since you posted and i just can't remember how i did it.

 

alright, i think i should have teh IACV clean first, instead of wd-40, carb cleaner doesnt hurt the TT engine right?

 

i don't rightly know. the IACV has plastic in it. i would expect it will be ok with carb cleaner, but i'd at least read the can first.

 

i had my RX7 IACV disassemble from the throttle, and clean with carb cleaner, didnt solve the idle problem until i had one of the clip unpluged.
alright, i am goin to look upmore threads about IACV, hope thats teh cause of the idle problem.

 

that's probably not the problem. what that says is that the aicv is functioning just fine, it's the signal that it's getting that's bad. temp sensor, tps, o2 sensors, any sensor really is suspect here. try disconnecting the maf at idle and see if that stops the searching.

 

You can run the puter diagnostic, theres an EGR code, it may be able to tell you if thats the problem.

Its hard to get to with the motor in the car in general.