idling problems

[nis14]

So I just bought this S14 95' and the engine has been swapped out for another KA (40K ish miles). And the engine is really acting up. The idle bounces from 1200 to 2000 rpm.

I tried to clean my AIV and it worked for like 3 hours and it started going that again. I checked the ECU and there are NO codes that are popping up. I tested the AIV soldnoid by applying the power to the harness. Basically applied power every in an 1 second interval, the thing is sometimes there was 1 click and some times there were 2 clicks, I'm wondering is the soldnoid bad???

I don't think that it's the EGR because no codes are pointing up on the ECU. I'm thinking it has to do something like the AIV because after I cleaned it idled perfectly at 750 RPM.

Alright genius nissan techs what is wrong with my engine

[NISTECH]

you cleaned your AIV for you purge air system and the car ran better or you cleaned your IAV for idle control?

[nis14]

oh I'm sorry I meant the IAAV, I sprayed carb cleaner into that big hose that is connected to the intake piping near the bend. worked good for 20 mins and went back to normal.

[NISTECH]

sounds like you might have a vac leak near the valve which is causeing it to" hunt" for a stable idle. spray your carb clean around the outside of the valve with the car running. if the idle stablized you got a vac leak

[nis14]

where exactly am I suppose to spray?

and this is my plan of action:

1, check for vaccum leaks, if that doesn't work2, clean the plunger and spring solinoid (is there a easy way to do this?3, then clean the AAV unit.

[nis14]

oh yeah and how do you check grounds?

sorry for the newb question...

[NISTECH]

spray around the valve and to check grounds loosen and retighten them

[nis14]

so checked ground and checked for vaccum leak

so I tried to take out and clean the iaav thing behind the engine, but it's impossible to get to it. thinking about just taking it to the nissan or a shop. I have a ABS unit so it's in the way. has anyone done this before?

what's funny is that before I cleaned the IAAV by spraying in the the tube, if I took the tube out from the intake tubing the engine would still run, but now if I take the tube off the engine just dies, so I'm thinking that the plunger is gunked up and not operating properly.

any thoughts or suggestion?

[NISTECH]

try to follow the info in 240 technical section there is a couple of stickys on it

[s13sr20chris]

i have seen idle probs after cleaning the throttle body and not adjusting the tps. base idle could also be off. the basic inspection section of fsm is very helpful here.

edit: when adjusting the tps dont do it the oldschool way. get out a feeler gauge and adjust it to the new spec.

[U12 2NR]

I don't see why it's necessary to adjust the TPS after cleaning the throttle body. The TPS wouldn't send out different voltage signals to the ecu with a cleaned throttle body. If the TPS was imporperly adjusted to begin with then that's a different story. I have a techtom mdm-100n, it makes adjusting the TPS voltage extremely easy.

[s13sr20chris]

i know what you are thinking and your logic is right on, but there is a catch. when you clean the carbon from the tb the butterfly may close farther than it would before. the ecu has a hard value of minimum throttle angle(this is zero volts naturaly) and a soft value(learned minimum). the soft value is the highest tps voltage the ecu recieves at closed throttle. this is a learned function to negate the lost travel caused by carbon build up. if you clean it and the ecu sees less than the soft value, it freaks. generally this will cause and idle of like 1500 rpm's. often it includes hunting as well. i have heard of low idles and stalling as well but never seen it do that myself. you can leave it alone and drive the car like that if you want. after 20 drive cycles it should have completely corrected itself. i learned about all this at the local nissan training center a long time ago.

[U12 2NR]

wow, now that i think about what you're saying, i can actually see it happening. thanks for the tip!

[s13sr20chris]

i stole it from the guys at tech school.:peace