KA24: KA24E Idle problem defined and solved - Nissan 240SX Forums
S13 240SX (89-94) Technical Questions Specifically for ALL S13's. (Including 180SX's, 200SX's & Silvia's)

 
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#1 Old 09-30-2011, 09:33 PM
 
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Exclamation KA24E Idle problem defined and solved

So, many of you probably comes across idle problems with the KA engines. I have bought both
89 AND 90 KA engines to show the difference in IDLE systems (also known as IACV, AAC etc..)

Since I did rebuilt the motor head to toe, everything gets kind of messed up, and i dont know
which one is for what motor, but thats not the issue.

IF you have the idle problem, you might tend to go to the IAC, but not sure which one is bad.
This is why I made up a report on what I find very interesting about the IAC system.

PS: IAC is VERY important if you have auto start, because winter in chicago doesn't help. lol.

EVERY PIC IS ON ITS RESPECTIVE SIDE.!!!!

Here is the picture of two VERY similar IACV from a KA24E (not sure which of what is what year)
As you can see, the IAC housing bolt pattern is exactly the same. Both of them will bolt up to
the intake manifold housing. BUT the IAC itself is a different design.



This is the picture of the IAC itself. One is obviously shorter than the other... Not only that, the "pintle" design is also different.



This is the difference in the IACV housing again in super close up picture. As you can see, the one on the right has a spring loaded extra pintle which is then actuated by the OTHER small pintle on the IAC itself (refer back to previous pic) As the one on the left is empty, because the IAC for it has its own "pintle housing" you can say, and the pintle moves in the housing.



This is the IAC housing difference again, as I said before the IAC housing on the left is hollow,
while the one on the right has its own spring loaded pintle built in.



Another side picture dfference.



Swapping IAC in its entirity is very easy, 4 10mm bolts and bottom rubber hose that goes to the breather. NO you cannot just swap the AAC by itself unless you have the same exact part,
If you end up in my position, just swap the whole IAC, and it will 100% work. tried...

This difference in design is between the KA24E 1989 motor and 1990.

Hope this helps some 240 die hard fans out there. My first writeup. Hope this really help other people.
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#2 Old 10-01-2011, 12:36 AM
 
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89/90 had ka24e 91 and up had ka24de.. also.... iacv is isnt the only thing... a stuck aiv (pair valve) will really mess with you..not trying to jack your post/be a jerk

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#3 Old 10-01-2011, 01:08 PM
 
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See, I have a 1990 KA24E with the IACV on the left with the long pintle on it. I've been having idle issues lately and it is probably due to the fact of my IACV. I have cleaned it and greased the springs/pintles in it and it seemed to not get better, it is the same or has gotten worse a little.

With my idle, if Im at idle the revs are stable at 1100 RPM. If I decide to open the throttle up to 2000 RPMs and let off, the idle will drop and fluctuate between 950-1000. After about 25 seconds in idling, the idle with jump back to the stable 1100 RPMs.

From a couple 240 owners claim you cannot clean and grease the parts in an IACV. The parts/springs tend to wear down and get old. You, personally, would have to replace the WHOLE unit.

By the way: no vacuum leaks. Only vacuum present are: FPR, SCV, Brake booster, Charcoal canister Purge and VC signal lines. I still have my EGR hooked up. Only problem is that I applied vacuum to the valve and it didnt not open. It must be stuck closed/carbon deposit buildup.
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#4 Old 10-02-2011, 02:43 AM
 
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89/90 had ka24e 91 and up had ka24de.. also.... iacv is isnt the only thing... a stuck aiv (pair valve) will really mess with you..not trying to jack your post/be a jerk
89/90 had kae, 91 and up kade. right, this is IAC from 89 AND 90. both ka24E. idk why nissan would REdesign it. but they did. and as far as the AIV, idk how it would effect the idle, its right after airfilter and hooks up to the housing... anyway, it might, might not, I never had that problem. took my AIV out and plugged the intake. I feel that AIV's useless... so is the charcoal canister.
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#5 Old 10-02-2011, 02:49 AM
 
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The AIV (when it fucks up) lets exhaust come back up through it and the intake sucks it up. Basically when the AIV goes bad it turns in to a mega EGR valve, lol.
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#6 Old 10-02-2011, 02:56 AM
 
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Quote:
Originally Posted by Riedell Last Post
See, I have a 1990 KA24E with the IACV on the left with the long pintle on it. I've been having idle issues lately and it is probably due to the fact of my IACV. I have cleaned it and greased the springs/pintles in it and it seemed to not get better, it is the same or has gotten worse a little.

With my idle, if Im at idle the revs are stable at 1100 RPM. If I decide to open the throttle up to 2000 RPMs and let off, the idle will drop and fluctuate between 950-1000. After about 25 seconds in idling, the idle with jump back to the stable 1100 RPMs.

From a couple 240 owners claim you cannot clean and grease the parts in an IACV. The parts/springs tend to wear down and get old. You, personally, would have to replace the WHOLE unit.

By the way: no vacuum leaks. Only vacuum present are: FPR, SCV, Brake booster, Charcoal canister Purge and VC signal lines. I still have my EGR hooked up. Only problem is that I applied vacuum to the valve and it didnt not open. It must be stuck closed/carbon deposit buildup.
If you have a power probe (about $160...eBay sells it i got it from a snap-on truck for a slight discount) you can check if ecm gives ground, one pin from the harness should give constant power KOER, and the other should be GRN about 3-6 times per sec on cold engine. Other than that, try check continuity on the IAC itself... give power and grnd while holding the pintle to see if it retracts (clicks, you will see it move in and out) . if you see good ecm command (GRN) than ecm is good, if you DONT have continuity on the IAC, you have a bad iac. It doesnt matter which IAC you use, just use the respective housing. both IAC housing fits stock KA24E intake manifold. give it a shot. New IAC would cost you about $144 from rockauto.com

As far as the EGR, stuck closed would be okay. stuck open would most probably stall the car on idle INSTANTLY. you might want to check outher system, as in Ignition (distributor cap and rotor for oxidizing) wires, plugs.

I would NEVER grease anything on the iac. air goes thru it, grease would just block air. other than that, iac doesnt move with a lot of friction, grease would be unnecessary (actually bad). just simple brakes cleaner should do. take idle adj screw out, spray brakes cleaner, in and out. then adjust.

May be give this a shot, remove the AIV. see if it runs better. its the one black plastic box hooked up to the air filter housing. I removed mine, Id ont see a point in emissions anymore, hybrids and nissan leaf balances the eco system.
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#7 Old 10-02-2011, 03:03 AM
 
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Quote:
Originally Posted by *ka24e* Last Post
The AIV (when it fucks up) lets exhaust come back up through it and the intake sucks it up. Basically when the AIV goes bad it turns in to a mega EGR valve, lol.
mega EGR valve... lol!! *picturing a MEGA egr.* hahaha. that was a good description...
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#8 Old 10-02-2011, 04:26 PM
 
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it really does though..the engine will die when you punch in the clutch cause the rpms drop then get hit with exhaust and it cant handle it...try being in the middle of a tight turn and then all the sudden you lose powersteering...lol

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#9 Old 10-02-2011, 04:31 PM
 
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Quote:
Originally Posted by byonata Last Post
If you have a power probe (about $160...eBay sells it i got it from a snap-on truck for a slight discount) you can check if ecm gives ground, one pin from the harness should give constant power KOER, and the other should be GRN about 3-6 times per sec on cold engine. Other than that, try check continuity on the IAC itself... give power and grnd while holding the pintle to see if it retracts (clicks, you will see it move in and out) . if you see good ecm command (GRN) than ecm is good, if you DONT have continuity on the IAC, you have a bad iac. It doesnt matter which IAC you use, just use the respective housing. both IAC housing fits stock KA24E intake manifold. give it a shot. New IAC would cost you about $144 from rockauto.com

As far as the EGR, stuck closed would be okay. stuck open would most probably stall the car on idle INSTANTLY. you might want to check outher system, as in Ignition (distributor cap and rotor for oxidizing) wires, plugs.

I would NEVER grease anything on the iac. air goes thru it, grease would just block air. other than that, iac doesnt move with a lot of friction, grease would be unnecessary (actually bad). just simple brakes cleaner should do. take idle adj screw out, spray brakes cleaner, in and out. then adjust.

May be give this a shot, remove the AIV. see if it runs better. its the one black plastic box hooked up to the air filter housing. I removed mine, Id ont see a point in emissions anymore, hybrids and nissan leaf balances the eco system.
I checked ohms on both systems and operate at 10 ohms. I did remove my AIV, SCV Solenoid Control valve, FPR Solenoid, EGR Solenoid, BPT and probably a couple other things i forgot to add. Like I said, the only things getting VACUUM are: FPR, SCV, and Charcoal Canister (Purge line right after the throttle body on the plenum [to the left of the TPS] and the Vacuum Line to operate the Canister valve is right on top of the throttle body [does not operate at idle, only sucks vacuum when the car is cruising])

The only Ignition I did not change were the wires. My ignition coil is at 1 ohm, should be .7 ohms. New NGK Copper tip plugs and the cap and rotor are in good shape.

Edit: One day coming very soon, I will pull off the plenum & intake manifold to give it a good cleaning in a parts cleaner tub (dad owns one in shop where EPA comes in and take it every so often to clean it out). I'll pull my EGR valve off, block it with this plate I have with gasket, and also probably replace the PCV Valve because I dont know the history of my car! Whoever had it before me did not take care of the car very well! :/

1990 240SX; KA24E; Auto, A/C. NicoForums, 240sxforums, KA-T.org

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#10 Old 10-02-2011, 07:50 PM
 
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Quote:
Originally Posted by byonata Last Post
89/90 had kae, 91 and up kade. right, this is IAC from 89 AND 90. both ka24E. idk why nissan would REdesign it. but they did. and as far as the AIV, idk how it would effect the idle, its right after airfilter and hooks up to the housing... anyway, it might, might not, I never had that problem. took my AIV out and plugged the intake. I feel that AIV's useless... so is the charcoal canister.
I took the AIV out because of what problems it can cause when the AIV decides to stop working. It can even mess up that MAF sensor of yours.

The charcoal canister though, in my point of view, is a necessary item. Ask yourself this question: what will happen when the fumes are exposed to the atmosphere without being saved? Two things: one is that the hydrocarbons in gasoline will pollute the atmosphere and "could" cause emission testing to not come back okay. second is that when the gasoline fumes leave without being caught/filtered, this in fact will lower your gasoline level in your gas tank. Yeah, people on here will say that it won't lower it that fast that quickly.

Now ask yourself: i need my car to commute around to get jobs done, what are ways to save money so im not dumping so much for gasoline? A small step is keeping that charcoal canister

But hey, everyone has their own respective ways to keep the engine bay cleaner for less weight or/and more power. Just thought i would share some thoughts on the charcoal canister if you do decide to hook that baby doll back up. Did you know: Toyota Prius's have their own charcoal canister in the air filter box combined with the air filtration?

1990 240SX; KA24E; Auto, A/C. NicoForums, 240sxforums, KA-T.org

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#11 Old 10-02-2011, 11:20 PM
 
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plus the engine bay will smell like gas. had mine off for 5 mins to relocate it and it was very noticeable, and when i interned at toyota, yes the prius' priuses? either way, they do have a charcoal canister.

Quote:
Originally Posted by boxfresh Last Post
Wasnt directed at Midnight, I like him (all homo).
Quote:
Originally Posted by collegekid Last Post
I mean shit, a prelude in need of pepto bismol farted past me today and it ruined the rest of my day.
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#12 Old 10-03-2011, 12:45 AM
 
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plus the engine bay will smell like gas. had mine off for 5 mins to relocate it and it was very noticeable, and when i interned at toyota, yes the prius' priuses? either way, they do have a charcoal canister.
That's totally right: the engine bay will smell like gas, maybe the inside of your car too!

Don't be lighting a cigarette or any soldering around that hose. You can cause a serious explosion!

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#13 Old 10-03-2011, 01:08 AM
 
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haha, i know where "laughing" about it, but it really will cause a serious fire/explosion. id keep it on for safety reasons man

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