racepar1

I have read in SCC magazine's 240 buyers guide and on some forums that adding a ground to the aac harness will help with idle issues. I have searched here, google, and a failed attempt at nico to find more information to no avail. I looked at a wiring diagram on mitchell but I saw no ground for the aac or ficd valves, just a power wire and a control wire that goes to the computer. Can anyone shed more light on this? I'm going to the autocross event at the performance nissan meet this weekend and would like to have a normal idle.

grachman

Some people might not know what they are talking about. Im guessing it is grounded by its physical interface with engine block. Some people might add a gasket which would destroy the ground. a wire from the iacv to engine block would be how i would do it. just test if it helps. very unlikely.

racepar1

There is NO ground wire according to the diagram that I have.

Def

There are two grounds on the 4 pin harness for an S13 SR from what I remember.

There is a gasket between the AAC valve and the manifold stock.


I seriously doubt a bad idle is a result of an improper ground to your AAC valve, but you never know.

sean350z

S14/S15 AAC valve (non-a/c activated idle) has two wires on the harness one that goes to ignition and the other to the ECU. I'd assume that the ECU could act as a ground or switch to complete the circuit when it's needs to be.

The FICD valve (a/c activated) has a constant ground and power goes to it from the A/C relay when the A/C is switched on.

You may not want to have the AAC valve constantly grounded because it will not function the way it needs to, judging by the diagram.

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grachman

I looked at an old tutorial I did along time ago and it looks like the only ground comes from the the ecu.ie ecu sends ground signal when it wants aac open. People might mean to improve the general ground to the ecu or to improve ground for the engine and other metal parts of car. Im beginning to think that most of the stuff said in the forums is very unreliable or the info is lost in translation.

http://forums.nicoclub.com/zerothread?id=251133

racepar1

I found the problem! I am going to do a write up on how to premanently fix your f-ed up idle issues on KADE's.

Xandy Boosts

I look forward to this. Don't forget to update us

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undesiredshoe

The four bolts that touch the valve already ground it.

darkslide

oo00o i cant wait!

grachman

the aac solenoid receives the ground from the computer. so anyone saying it needs a second ground is incorrect.

thatdrifterguy

can someone explain what idle issues he's talking about??? maybe thats whats wrong with my car too.

DaPCWiz

I too am looking forward to this....

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racepar1

Basically a high idle that seems to do whatever it wants to do. And I must correct myself, I THOUGHT I found the problem! I was initially wrong though. I have now found the actual problem though.

Def

Either vac leak or no coolant flowing to the valve.

racepar1

Wrong and wrong! No vacuum leaks and no coolant flow problems. Coolant doesn't flow through any of the valves that control idle anyways, unless you wanna count the throttlebody that is.

nastjuid

it's been 30 minutes, where's that write-up?! j/k :P

Put me on the list of people who want to see how to solve every idle issues with a KADE :P

grachman

there 50 zillion potential reason for bad idle.

racepar1

There are only 3 valves that affect the idle (not including the throttlebody that is). Where do you get 50 zillion reasons from 3 measley valves and like 12 wires?

johngriff

Timing
TB Chalk
TPS broken or not setup
AIR in Cooalnt
AAC Valve either not working, stuck, or the screw is misadjusted
Bad AFM
Bad Injectors
Bad Coolant temp sensor
Worn/broken/high resistance wiring on ANY of these sensors
Vacuum Leak
Exhaust Leak
God hates you

USE THE F'ING Engineering Flow Sheet to diagnose idle issues.

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Def

On S13s coolant does flow through the aac valve, block off the coolant line and you'll get a high idle until it heats up, then high idle when you move again and it cools down.

What did you think the two barbs on the aac valve are for?

racepar1

There ar NO hoses coming off of my aac valve and I am SURE that it is an s-13 motor. Are you sure you're not thinking of an s-14 KA?

racepar1

LOfuckingL!

Fuck the diagnostic flowcharts! I hate those god damn things! Waaaayyyyyy too complicated and they usually lead to you chasing your tail. Every single time I have ever tried to diagnose a car the way the flowchart says I end up confused, if I just look at the wiring diagrams and figure out how everything works I usually find the problem pretty quickly. Pretty much all of the causes you listed would have other symptoms as well and would only happen if you or someone else screws with the car and messes something up. The only reason to check most of the things on your list would be if you just bought the car or if it just had a repair done to that system.

Def

My KA memories are a little hazy, but I swear I helped a friend change out his intake mani coolant hoses and the AAC valve had some, maybe I'm mistaken.

The S13 SR20DETs *DEFINITELY* have coolant going to the AAC valve.. maybe that's why they're faster than KAs.

johngriff

Well what was your answer / solution to this idle problem. There really isn't much any thing else in the eccs system.

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racepar1

I'm going to post a new thread on that as soon as I get a chance to get some pictures as this thread is pretty dead and has turned into a guess fest and mild argument. Unfortuanetly I was in too much of a hurry to get the car running to take good pics while it was apart because I forgot my camera. So i'm going to have to find a few good exploded diagrams from mitchell to help illustrate what I'm talking about.

grachman

the aac supplies air. the coolant is much hotter than the air.

Def

???

The coolant melts a wax element in the AAC valve and causes the airflow supplied by the valve to drop and go down to a hot/warm idle level. No coolant = rarely melting the wax = high(cold) idle almost all the time.

grachman

none of the 240sx's have coolant going close to aac valve. we have an air regulator that supplies extra air when coolant temp sensor says it is cold.

Def

S13 SRs most definitely have coolant going to the AAC valve. Look at a FSM.

Please stop talking out of your ass.