Another low idle thread...

B18c2. Stock.

Symptoms:

* Low idle (300-400 RPM) after warm up. Warm up idle is normal and car idles normally for a short time before completely warming up.
* Never stalls. Seems happy to live life at 300 RPM.
* Not jumping/hunting. Just sits there steady.

Things I've tried:

* Cleaned the ICAV a couple of times. Was not blocked etc.
* Replaced coolant and (I think) bleed and air-purged it.
* Visually checked the vacuum tubing, seems fine.

I don't wanna go messing with the idle control screws as it was fine for a long time, haven't changed anything significant.

***Any ideas before I just replace all the vacuum tubing? Really need tiny friggin' hands to get to that little black box under the intake :P

So vacuum lines smoked out. Nada. Coolant topped up, burped all good. Swapping o2 out with another tomorrow and will see. Read every thread I could find. Sooo many posts like mine. Zero fvcking solutions. Like they either gave up or didn't bother to post answer..


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Is the throttle body clean? How about the mass air flow sensor?

Mass air sensor itself is clean. Throttle body next on the list, thanks for reply.


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Throttle body cleaned. Still not big difference. Adj idle screw also not helping. Next step checking Fast idle wax thingy..

Do you notice a slight increase in rpm when you turn on the air cond?

Air-con has been removed.

Reading through the service manual there's a few troubleshooting guides which mentions blocking the top or bottom port in the TB with your finger. When blocking the bottom port, there is significant suction, but no change in idle. When blocking the op port, the engine almost dies. Hmmmmm. Make's me think I need better trouble shooting skills.

I'm just trying to figure out if the stepper motor on the iacv is working. Does the rpm increase if the headlight (and other electrical accessories) is turned on?

How many turns did you adjust the idle screw? The screw acts as a mechanical valve.

One hole on the throttle body connects to the iacv and the other one connects to the fast idle controller (the waxy valve you spoke of before).

When you adjust the screw its a good idea to count the number of turns so that you can return it to the original setting.

Is your air filter OK?

I only turned it -90 degrees, so from 12 to 9 o'clock.

The light on make the revs drop like its adding load to the engine.

Air filter fine. Had same revs when filter was off today to clean tb.

Quote:

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Originally Posted by PJT

I only turned it -90 degrees, so from 12 to 9 o'clock.

The light on make the revs drop like its adding load to the engine.

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Technically the iacv motor should compensate for this and increase the rpm to the setpoint. Maybe this is faulty.
It is worth turning it the other way, maybe 180 degrees and see if it increase the idle.

..have you reset the ecu yet?

Quote:

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Originally Posted by Martin77

Technically the iacv motor should compensate for this and increase the rpm to the setpoint. Maybe this is faulty.
It is worth turning it the other way, maybe 180 degrees and see if it increase the idle.

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I did try that but turning clockwise actually reduced the idle :/

"..have you reset the ecu yet?"

Yeah, I dod every time I change something, help :(

Take it to genuine Honda dealer

Prepare visa for workout

user mocchi would know the answer but he not online anymore :(

Quote:

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Originally Posted by YeahByuddy

Take it to genuine Honda dealer

Prepare visa for workout

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Lol. My local Honda dealer is pretty disappointing. Every time I get parts from them they have no idea. Plus they rolls their eyes whenever I tell them I have engine swap :(

what state? if nsw go and see BYP racing,theyre honda gurus

Quote:

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Originally Posted by YeahByuddy

what state? if nsw go and see BYP racing,theyre honda gurus

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I'm in Victoria. But central/north.

Just reading more. According to the shop book. There should be no suction from lower port after warm up. So FITV is dodgy. But since a working valve restricts air after warm up, would a broken one give me a high idle, not low? http://uploads.tapatalk-cdn.com/2016...50c0635fbf.jpg

The more I read the more I think IACV is culprit. But apart from cleaning it, things I could try are changing gasket and checking electrical connections.

My gut feeling is also a faulty iacv.
If you turn it anti clockwise 180 degrees (you could try a full turn), it should manually let air through the engine and increase the idle rpm. This is not going to fix a broken iacv but will make the engine idle better.

Thanks, man. I will try. Have ordered the little 'figure 8' gasket and will get the multimeter onto the connection when I get time. These suckers seem to be quite expensive to replace. And I've been burnt before buying used replacement parts. Ah 90's car life!


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This will be a great learning curve for you. I went through the same thing.

Calibrating the tps sensor wouldn't hurt.

Definitely replace iacv.tappets,timing,it's not hard.learn it all,know your engine. Then you'll be the one giving advice.

With the electrical load lowering the idle,a mega raizin is awesome. Watch out for ebay copys..

good luck mate.

Thanks for all your help guys. I'm starting to get my head around the air flow pathways. Adjusting the idle screw fixed it but I can tell it's just a band aid and still feels rough. Been reading a lot of your how-to guides, Beeza. Wealth of knowledge thanks man. Is it really worth shelling out $200 for icav? Was hoping to try and "refurb" mine :P will keep you posted :)

Quote:

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Originally Posted by YeahByuddy

what state? if nsw go and see BYP racing,theyre honda gurus

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Hahahahahaha worst advice

Cheers man,a few guys on here remember me when I was a noob not too long ago,so ya gotta commit ya self to get anywhere with cars.
200 is way exxy for just an iacv,I would personally put up a wtb thread on here and hopefully somebody has.

Have u tried taking the iacv off and opening up the gap with say a screw driver?just a tad,not too much.

I have found they get a bit stuck.they can also become loose or stuck completely open.

I haven't read into it but there's a magnet in there plus the sensor which together regulate the air gap for idle (iacv).

With the gap opened a tad,u can then turn the idle screw back.

The idle/air screw is just air.not like the old carbys that has an air/fuel mixture screw.if ya touched that thinking it was the air screw,...good luck getting it right again.yeah,so don't be afraid to play with that whenever you want.

Keep us posted.

What's up with byp dave? I'm not down with the what's goin on but benny was only ever a champ with me.

Quote:

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Originally Posted by beeza

Cheers man,a few guys on here remember me when I was a noob not too long ago,so ya gotta commit ya self to get anywhere with cars.
200 is way exxy for just an iacv,I would personally put up a wtb thread on here and hopefully somebody has.

Have u tried taking the iacv off and opening up the gap with say a screw driver?just a tad,not too much.

I have found they get a bit stuck.they can also become loose or stuck completely open.

I haven't read into it but there's a magnet in there plus the sensor which together regulate the air gap for idle (iacv).

With the gap opened a tad,u can then turn the idle screw back.

The idle/air screw is just air.not like the old carbys that has an air/fuel mixture screw.if ya touched that thinking it was the air screw,...good luck getting it right again.yeah,so don't be afraid to play with that whenever you want.

Keep us posted.

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All good. I marked it with paint before I messed with it :P Will put up a WTB, thanks again.