low idle/vacuum when cold, how do you deal with it?

[jt15833]

ever since i put on KA24DE alternator and electric fans, my engines been idling really low when cold (500) and vacuum ~14. If I drive around for an hour everything is fine 18-19in.hg. and 800rpm idle, but the cold is a big issue. i have to keep blipping throttle so itll idle right any solutions

[MegasquirtCA]

move down to florida.

[float_6969]

move down to florida.

LOL, Seriously though, it's probabally a bad AICV. Basically the cold start valve located under the TB. They get stuck frequently. I think one from an SE-R will work. You can try cleaning it out with some carb and choke cleaner, but I've had limited success with that.

[dattodude]

float's right on the money.

These things commonly fill up with crap so carby cleaner will help there.

Might also be the base idle is too low, or the base idle bypass is choked up too.

So....with A/C and headlights off, when engine is hot and idling properly as you expect, pull off the AAC Valve connector. The large of the two on the side of the plenum. I believe the idle will drop a couple of hundred revs.

There is a 10mm hex bolthead on the back-side of the AAC and FICD valve unit. This is the base idle mechanical adjuster.

Using the tachometer, and a 10mm spanner, adjust the base idle until it is 800-850rpm.

Once this is done, reconnect the AAC valve connector. The ECU will now have to do less work to manage your idle.

Chris

[c-rad]

Using the tachometer, and a 10mm spanner,

wtf is a "spanner"?

[float_6969]

LMAO!spanner = wrench in America Engrish

[rico05]

FYI a new Air Regulator can be used from a B13 Sentra SE-R. But be warned: They are ~$95 new from Nissan. I bought a supposedly working one from Dee and it did not fix my low cold idle. Just make sure that before you spend the $$$ that there are no other issues (vac leak, low compression, etc)
Modified by rico05 at 12:09 PM 4/1/2006

[XTCshri2222]

move down to florida.

I did, best mod ever =)

[dattodude]

wtf is a "spanner"?

Yep I was referring to a Ring/open ender :-)It's funny that you didn't know what a spanner is.

A chinese guy over the road from my house used to call them a 'spalla'..as kids, we used to think that was pretty funny.

Chris

[biosehnsucht]

actually the IACV is the idle control on the intake mani.

ya'll are talking about the Air Regulator.

I replaced mine and it fixed alot of my cold running problems (even non idle).

[mikesim]

would the non-idle problems be like a large delay between throttle input and response? when my car's cold, it doesn't respond at all.

so i need to replace both the IACV and the Air Reg, or just the Air Reg?

[jt15833]

what about if im going 40mph and approaching a redlight, i put car into neutral and revs come down fast to 500 then go back up to normal 800?

[MegasquirtCA]

would the non-idle problems be like a large delay between throttle input and response? when my car's cold, it doesn't respond at all.

so i need to replace both the IACV and the Air Reg, or just the Air Reg?

The Air Regulator is used for Cold Starts as the motor warms up it lets less air in until it gets to around 160* F then it closes and the IACV takes over, the IACV takes care of idle after the car is warmed up.

[float_6969]

He nailed it.

[Not_a_sr]

havent seen a Ca yet that liked cold conditions... mine never did no matter how many air regulators i went through.

[dattodude]

Please just go follow my instructions from earlier.

When the idle drops lots (then recovers) at a set of lights, or after revving the engine, this is the base idle not being set properly.

If the base idle is not set to 800-850rpm, then the ECU will compensate for the low lbase idle, by using the AAC Valve to bypass more air to raise the idle.

If the base idle is too low, the ECU has to 'save the day' everytime the engine gets down to these low RPMs.

This only occurs when:1. The base idle is not set properly2. the idle circuits are choked up with carbon rubbish from the turbo or crankcase ventilation oil particles.

Please go out to your garage and follow my suggestions. Otherwise you will spend heaps of money and not fix your problem.

Chris

[rico05]

A lot of times the AICV will get clogged. I know mine was when I pulled it apart and cleaned it. Also, many folks seem to have good luck bypassing it and simply setting thier idle by throttle cable tension.

Dattodude: You have to remember that we in the US that have CAs have swapped them in, and unlike all of the killer cars in Oz that have done the same, many of us are running the standard ECU, which compounds the problem. I have seen literally dozens of threads on this and many of us never get the problem fixed until we go stand alone ECU.

[fraz]

What he means is the base idle is what the engine will idle at with all the other idle control, and cold start valves disconnected.You adjust the nut until its at the right revs with the throttle closed. That way, when you some to a stop at the lights, the rpm wont drop below what you have it set to and there wont be the delay while the ecu reads the low idle and opens the valve to compensate.

By having the base idle set correctly, the ecu wont need to make any adjustments except when the engine is under cold start conditions.

Sorry for the long winded post, im half asleep

[dattodude]

Thanks Fraz..you know what I'm talking about.

I was running the standard ECU on a ca18de and ca18det for 8 years, and have read the CA18 manual several times. I know a thing or two about the factory setup too :-)

Is the KA24DE alternator higher output than the CA one?If it's not keeping up with the current requirements it will make the engine idle drop when current drain is high. It's just like when you put the high beams on. If the alternator/regulator is correctly sized, and the battery is correctly sized, the idle shouldn't drop.

Chris