B16A2 Idle problem (intermittent)

Hey guys

My car has a weird little intermittent idle problem that comes and goes. After the car is warmed up, the idle will go funny and bounce up and down from 200rpm - 1200rpm. This happens for a few minutes before it stabilises itself at around 700rpm. This will also happen every so often when coming to a halt at traffic lights but at other times will be just fine.

The car drives perfectly fine without any hiccups and has not been modified in any way either. Motor is a stock B16A.

I've taken off the IACV and gave it a clean but made no difference.

Any ideas guys?

I should also note the Malfunction Indicator Lamp (MIL) is NOT on.

Checked for vacuum leaks? If you have an early model b16 you may need to adjust the fitv.

it's a 2nd gen B16A2..

fitv.

OBD2 motor - no FITV

Quote:

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Originally Posted by dorikin

OBD2 motor - no FITV

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Have you checked for vacuum leaks? is your throttle cable or throttle body plate getting stuck slightly open?

Throttle cable is fine.. I'll check the TB plate, but if it was slightly open wouldn't that generally cause a higher idle thats steady?

I've had a look around vacuum hoses for leaks but couldn't find any.

I would describe it more as a drop in idle that bounces back up then drops again, etc. Imagine someone putting their hand over your TB which cuts off air and drops the idle to 200rpm, and then takes their hand off which shoots the idle back up and so on.. mine feels something like that.

I'll try and upload a video

It can cause that annoying surging if it's not sealing properly.

The spring on the tb can wear and cause the tb plate not to seal sometimes aswell.

Just make sure the tb cable is adjust properly too..

My friend has had the same sounding problem,I'll ask him

Quote:

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Originally Posted by dorikin

Throttle cable is fine.. I'll check the TB plate, but if it was slightly open wouldn't that generally cause a higher idle thats steady?

I've had a look around vacuum hoses for leaks but couldn't find any.

I would describe it more as a drop in idle that bounces back up then drops again, etc. Imagine someone putting their hand over your TB which cuts off air and drops the idle to 200rpm, and then takes their hand off which shoots the idle back up and so on.. mine feels something like that.

I'll try and upload a video

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Its my understanding that if your rpm is too high when your idleing your ecu will cut the fuel untill the rpm drops, then when it reaches a lower rpm it will turn the fuel back on which will repeat the cycle. This can be caused by too much air getting into the engine weather it be from a vacuum leak, improperly adjusted idle screw, TB plate not sealed etc

If you have ruled out vacuum leaks and you have checked your throttle body is sealing properly i would probably test the IACV next and make sure its still functioning properly.

I adjusted the idle speed today following the FSM instructions.

With IACV disconnected it was idling at 200rpm, so increased it to 450-500rpm by adjusting the idle screw which equates to roughly 750rpm with IACV connected

But still hasn't fixed the erratic idle. What is the best way to test the IACV?

Also got some readings from the TPS. 0.5V closed and 4.6V WOT.

Quick video


http://i18.photobucket.com/albums/b1...h_SNC02710.jpg

Your iavc could be a bit slow reacting, and it overshoots. I was told to spray some light lubricant like wd40 in there after cleaning it to give a bit of lubrication and prevent it sticking etc.

Easy way to test it is swap it out for a working one ie if you know someone with the same sort of car just see if you can borrow theirs to see if it fixes the problem if you cant do that just follow the procedure for testing in the service manual. Ive heard a faulty o2 sensor can cause idle issues as well so might be an idea if you have ruled out everything else to check that out.

Your TPS should be 0.48 volts when your throttle plate is fully closed, id adjust it slightly.

Does the idle problem only happen while applying the brake by any chance?

Are U sure there's no FITV,There isn't a spot to insert an allen key on the end of the IACV is there?

Is the timing correct?

I love these problems :) Not easy...

My friend (ekcoupe) swapped his timing belt and 70-80% of his problem went but I think his was a number of things.

I agree to swap the 02 sensor anyways.They are important to be working at 100%

Subscribed same problems here

^^^ Have you tried using an ek4 ecu yet? swing me a pm with an update if you want and ill see if i got any ideas.

Quote:

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Originally Posted by beeza

Are U sure there's no FITV,There isn't a spot to insert an allen key on the end of the IACV is there?

Is the timing correct?

I love these problems :) Not easy...

My friend (ekcoupe) swapped his timing belt and 70-80% of his problem went but I think his was a number of things.

I agree to swap the 02 sensor anyways.They are important to be working at 100%

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Beeza i wouldnt be surprised if there is no FITV, from what ive read(workshop manuals and fourms) it appears the fitv's start dissapearing around the mid to late 90's, it seems the performance engines with manual transmissions like the b series are the first that moved onto using the ECT to bump up the idle while the automatics and economy engines like the d series seem to retain the use of an fitv for a while longer.

And definately agree with you on idle issues not being easy lol, too many things effect the idle so it makes it hard to diagnose, especially on the net lol.

Such a good challenge aye.Since I watched that vid on the problem,I cant stop racking my brain but yeah,too many things to check :)

Timmy reckons his car has no FITV but there's a star key (5 sided) insert on the end of the IACV,and that can be nothing else but a FITV I reckon..

We just haven't looked hard enough to find the key to turn it.We'll,if it was my car,I would have hehehe

I see the SOHC in ya avatar! WOOT WOOT!

Quote:

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Originally Posted by anjin

Your iavc could be a bit slow reacting, and it overshoots. I was told to spray some light lubricant like wd40 in there after cleaning it to give a bit of lubrication and prevent it sticking etc.

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I think you could be onto something. After watching this youtube clip, he says the IACV is prone to sticking on Hondas so I might take it off again and give it a better clean.

Quote:

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Originally Posted by TbM

Easy way to test it is swap it out for a working one ie if you know someone with the same sort of car just see if you can borrow theirs to see if it fixes the problem if you cant do that just follow the procedure for testing in the service manual. Ive heard a faulty o2 sensor can cause idle issues as well so might be an idea if you have ruled out everything else to check that out.

Your TPS should be 0.48 volts when your throttle plate is fully closed, id adjust it slightly.

Does the idle problem only happen while applying the brake by any chance?

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I'm gunna attack the IACV again, I have a hunch it could be that.

The FSM says TPS should be approx .49V and approx. 4.5V at WOT. How critical is it to get it exactly right.. mine is off by .01V and .1V
The other thing that sucks with my TPS is it can't be adjusted easily, I'm pretty sure you have to hacksaw it off.

Nah, don't need to have my foot on the brakes. I could have the handbrake up and it will still happen.

Quote:

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Originally Posted by beeza

Are U sure there's no FITV,There isn't a spot to insert an allen key on the end of the IACV is there?

Is the timing correct?

I love these problems :) Not easy...

My friend (ekcoupe) swapped his timing belt and 70-80% of his problem went but I think his was a number of things.

I agree to swap the 02 sensor anyways.They are important to be working at 100%

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Yeh I'm sure. My throttle body looks like this http://www.ff-squad.com/tech/tb/tb.nofitv.jpg
From what I understand OBD2 motors have their fast idle controlled by the ecu http://honda-tech.com/showthread.php?t=1447010

Which puzzles me because I'm running an OBD1 ECU P30 and I don't have any cold idle, fast idle problems..

Not sure if I remember any allen key on my IACV, mine looks like the bottom one here http://www.ff-squad.com/tech/sensors/iacv.jpg

Haven't checked timing (no timing light) but if it's worth checking then I'll get onto it.

O2 sensor replaced with a brand new one about 6 months ago

Kool kool

If that allen key is anywhere,it's where the arrow is pointing but sounds like there isnt one.

http://i774.photobucket.com/albums/yy25/beeza4/iacv.jpg

Best to get the tps spot on,ya gotta hacksaw the rivets off and replace with screws to adjust.

Not sure if it was asked but is the tb plate sealing properly and the spring on the tb strong as to close the tb firmly.

I'm pretty sure the TB plate is sealing properly. When I had the intake piping off, I plugged my thumb over the hole in the Throttle Body (that leads to IACV) and the engine stalled.

Would this mean I have a good seal around the TB

Dorikin my TPS was at 0.51 volts at closed throttle and i adjusted it and noticed a difference so would recommend doing it, i had to hacksaw a line in mine and remove it with a flat head but it doesnt take long. I dont think the wot reading is as important as the closed.

If you didnt clean the IACV properly the first time then that could still be causing your idle issues, use subaru upper engine cleaner or if you cant get that bezza knows another cleaner that works well and remember to let it dry before reinstalling it, reset the ecu when your done. Ive never needed to use wd-40 or other lubrcants when i fully clean the IACV, if its sticking its still dirty.

Quote:

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Originally Posted by beeza

Such a good challenge aye.Since I watched that vid on the problem,I cant stop racking my brain but yeah,too many things to check :)

Timmy reckons his car has no FITV but there's a star key (5 sided) insert on the end of the IACV,and that can be nothing else but a FITV I reckon..

We just haven't looked hard enough to find the key to turn it.We'll,if it was my car,I would have hehehe

I see the SOHC in ya avatar! WOOT WOOT!

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it seems hondas dont like idleing lol, its the engines way of telling you to stay at WOT :) The star key might be a torx screw, i think they might have 6 sides tho, i had a holden vectra a while back and most of the small screws and bolts had torx heads which is why it comes to mind.

Yep REppin that SOHC D series woot woot lol.

Quote:

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Originally Posted by dorikin

I'm pretty sure the TB plate is sealing properly. When I had the intake piping off, I plugged my thumb over the hole in the Throttle Body (that leads to IACV) and the engine stalled.

Would this mean I have a good seal around the TB

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if you did it while it was idle hunting then i would rule out vacuum leaks and throttle body not sealing, if you did it while it was idling normally it could just mean the TB plate was sealing nicely at the point in time but may still be intermittently leaking.

^^ Exactly!

Yes,U seem very cluey mate,excellent stuff.Will be great to put that knowledge into the y4 cause that's what it needs!

:)

Thanks mate, I think you have already done most of the DIY's for the y4 so i dont know what i can add lol, definately owe you some rep points when i can give them out as your DIY's helped me sort out the EK before i got my e-stack of service/workshop manuals:)

Thanks to U too mate,it feels good to give back as I've always said :)

The black thermal wrapping looks so MAD!

Quote:

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Originally Posted by TbM

Dorikin my TPS was at 0.51 volts at closed throttle and i adjusted it and noticed a difference so would recommend doing it, i had to hacksaw a line in mine and remove it with a flat head but it doesnt take long. I dont think the wot reading is as important as the closed.

If you didnt clean the IACV properly the first time then that could still be causing your idle issues, use subaru upper engine cleaner or if you cant get that bezza knows another cleaner that works well and remember to let it dry before reinstalling it, reset the ecu when your done. Ive never needed to use wd-40 or other lubrcants when i fully clean the IACV, if its sticking its still dirty.

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I'm definitely taking the IACV off this weekend and giving it a good clean. Beeza, what kind of cleaner would you recommend, some sort of carby cleaner?

Failing that, I'll re-adjust the TPS to exact specs..

Quote:

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Originally Posted by TbM

if you did it while it was idle hunting then i would rule out vacuum leaks and throttle body not sealing, if you did it while it was idling normally it could just mean the TB plate was sealing nicely at the point in time but may still be intermittently leaking.

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I'm fairly sure I did it while it was idling normally... I don't think theres any problems with the TB plate, it opens and closes very freely and seems to have a good seal

I might grab a can of carby cleaner and check for vacuum leaks anyway, I've never done it before so might be worth checking


Thanks for all the help guys. Rep points for all.. hopefully see some results this weekend :D

Beeza has recommended a product that is like subaru upper engine cleaner, heres a quote from one of his DIY's

Quote:

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Originally Posted by beeza

I only use Suburu Upper engine cleaner to clean with now OR another product which I reckon is subi upper engine cleaner in another bottle is 'Engine conditioner',it's a Japanese product,i.e Japanese writing on the bottle and it's brilliant.Carby cleaner is crap.

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Ive only used the subaru product as i live near a subaru service centre so its easy for me to get but i havent seen the japanese one around.

I still recommend setting your tps to the correct setting even if cleaning the IACV fixes the hunting issue.

Hopefuly you get this sorted out soon, Good luck :)

Thanks mate,yes it's 'super engine conditioner' :)

Cool Thanks guys. Beeza where would I be able to find this product? Im guessing it probably wouldnt be available at general auto stores like Repco?

I googled it and i think hes talking about "threebond super engine conditioner"
http://www.mcsonline.com.au/componen...t/tbd30-P0.gif
Its got japanese looking writing below the main label, call your local auto stores and ask if they stock it or if you have a subaru parts centre near by you can pick up some subaru upper engine cleaner for about $17 a can, they are a small can but very effective:thumbsup:

He is :)

Any good auto retailer should stock it mate.

Did some research and googling as well on the ThreeBond product and definitely some excellent reviews on it.

Gotta get my hands on it this weekend and give it a shot :D

Here's a list of ThreeBond distributors in Australia for anyone else wanting to buy the product: http://threebond.com.au/distributors.htm

And as a matter of fact Repco is listed at the top!

did the problem fix? i got the same problem on my b16a. it doesnt always happen but if it does its usually when im stopped at the lights. is it a problem if i leave it like that?

I went at it with the Engine Conditioner, taking apart the throttle body, adjusting the TPS and cleaned every thing including inside the intake manifold but it never ended up fixing the problem. It may have even made the idle problem more evident for a little while because I cleaned some of the seal between the throttle plate and throttle body bore.

But the Engine Conditioner did improve the throttle response and acceleration felt a lot smoother so I was happy with that.


The problem only ever seems to happen within the first 10 minutes of starting the car so it might be a sensor problem, possibly IACV?

Yeah my iacv has been changed and Erraticated the problem. But it still came back, hmm?

Dude,

since you have done all the IACV,TPS, TB testing/cleaning and still has the same erratic idle....then i would suggest for you to check the below;

-Inspect/adjust ignition timing
-Check/inspect/replace spark plugs
-Check/inspect/replace spark plug leads
-Check/clean/replace dizzy

what fuel RON do u currently have in your tank? sometimes dirty fuel can affect the idle due to the bad combustion in the fuel delivery to the engine.

worth a shot, i had similar prob ages ago, but cant remember exactly how i resolved it.

let us knw how u go....

That's the same as Timmy's (ekcoupe),only the 1st 10 mintues of start up..it's only minor now.

Stupid Honda's! :)

I've found replacing the spring on the tb helps as it gets old,loses its tension and lets in air.

Yeh my problem is only minor too so I haven't paid that much attention to it..

Thanks for the tips IV73CI, I run 98RON BP Ultimate. I'll try the things you mentioned and I also read up that bleeding your coolant might help so might give that a go too.

And if anyone has a spare working IACV, please let me know!