Removing IACV Success!! Fixing f20b Hum!

[StealthCF4]

I hated the way that F20b's and H22a's make that annoying hum at idle. And how they hold the revs up when changing gear.

So i figured that the IACV was the cause of both these problems. I made a block off plate to replace the iacv. As soon as i did this the car wouldnt idle, obviously. So i adjusted the throttle stop screw untill the car idled and then reset the Throttle position sensor on the back of the throttle body.

0.51 volts at idle and 4.5 Wide open were the settings i used. The car now idles perfectly at 700rpm. I have yet to see how the car will idle in really cold temps so that may be interesting. But im pleased with how it turned out, And the car is so quiet at idle now, no more loud humm.

If you leave the IACV pluged in to the loom you wont have any problems with CEL's

Has anyone had any problems with doing this before, or know of any problems that may arise.

One question i have is what to do with the left over coolant hoses that went to the IACV. I had previously bypassed the coolant lines from the TB and now the lines to the IACV are gone. Should i loop the lines, or just block of the lines coming out of the thermostat housing. I would rather just block them off as it would look cleaner, but im not sure if this is ok to do?

[d16a7]

loop them ... as that is the factory way the water is supposed to flow..

[doo0T!doo0T!]

Originally Posted by StealthCF4

I hated the way that F20b's and H22a's make that annoying hum at idle. And how they hold the revs up when changing gear.

I just always thought the revs staying up between gears was the big-arse flywheel? K20 accords do it too, it's horrible the first time you drive it.

[StealthCF4]

Originally Posted by doo0T!doo0T!

I just always thought the revs staying up between gears was the big-arse flywheel? K20 accords do it too, it's horrible the first time you drive it.

Nope its just the iacv/ecu doing it. Revs drop reasonably quick now.

Im not sure if its an ecu fault or if its intended, but everyone who drives my car hates the way it holds the revs up, once you get used to it then you learn to take foot off the accelerator a bit earlier than you normally would when changing gear.

I like it much better now, shifting seems much smoother.

[SIRTEC]

o mean!! i need to do that to my car, the noise and the high rev really annoys me, cheers man

[Chaos]

hmmm id consider doing that to my car, but its gonna be an absolute bitch to get to the IACV because theres about 5cm between that and the firewall... and its a torx nut isnt it?

[StealthCF4]

The TPS uses two torx screws to adjust it, I actually took off the throttle body to adjust it. The IACV uses two 10mm bolts and is on the front of the intake manifold. Thats on my car anyway. I would recomend doing this to an f20b but i dont know how it will handle cold starts yet so cant comment on that.

[StealthCF4]

I have just confirmed what i expected, the car doesnt like to idle when cold. Its not too bad tho, just have to feather the throttle for the first few mins of driving. Im not sure if theres any way of getting round it either, maybe just setting the idle a bit higher may do it?

Any ideas??

[StealthCF4]

I have just had a thought to change to an h22a throttle body that uses a FITV, not sure whether the idle ports would match up to the IM though.

[Coupe-R]

I hated the way that F20b's and H22a's make that annoying hum at idle. And how they hold the revs up when changing gear.

never noticed this at all when i was tuning Danielles H22A eg civic???

No noise, and no holding the revs up high between gears on the stock ecu, or on the reprogrammed ecu. Holding revs up between gears to a degree is actually a good thing, easier to change gears. Sounds like yours was going mad tho.

as for increasing idle with a removed IACV, I would tend to use the idle screw adjustment to bypass air past the throttle plate. Rather than holding the actual throttle open a little bit on the stopper then recompensating the tps for that.

it may actually mean now that when the throttle is ACTUALLY open at 50% your ecu thinks its open 30% etc because of your TPS adjustment.

Won't matter too much though.

if you have A/C try turning it on at idle, also the lights, rear demist everything all at once. See what happens.
Also when cold, try it.

The IACV is there to compensate for all idle conditions, I would never remove it as it would drive me mad, unless you want to idle at 1000rpm+ all the time?

Yes you could try the FITV OBD1 H22A TB to help with cold starts.

[StealthCF4]

You are talking about a pre obd2 H22a, i think this only accomodates for obd2 f20b's and h22a's.

There is no idle screw on the obd2, it is all controlled by the iacv. Including cold start controll. Hence why there is no FITV on the throttle body.

[StealthCF4]

Originally Posted by Coupe-R

it may actually mean now that when the throttle is ACTUALLY open at 50% your ecu thinks its open 30% etc because of your TPS adjustment.

The throttle position sensor still reads 4.55 volts at WOT. And i dont really think that the plate position will matter, it would have only been opened about 1 degree i think, It doesnt take much to get it to idle.

[Coupe-R]

yeh if its only a small adjustment it won't matter,

There is no idle screw on the obd2, it is all controlled by the iacv. Including cold start controll. Hence why there is no FITV on the throttle body.

Take a pic of your TB and show me!
Cold start is controlled by the IACV alone on OBD2 yes, but no idle screw

[blizard]

There will be an idle screw on the tb

Originally Posted by Coupe-R

as for increasing idle with a removed IACV, I would tend to use the idle screw adjustment to bypass air past the throttle plate. Rather than holding the actual throttle open a little bit on the stopper then recompensating the tps for that.

With a blocked off IACV the idle screw won't have any effect - have a look at a throttle body and manifold. The idle screw air channel ends up in the same passage as the IACV. So if the IACV is removed and replaced with a plate then the only adjustment is with the butterfly stop grubsrcew.

[StealthCF4]

Originally Posted by blizard

There will be an idle screw on the tb


With a blocked off IACV the idle screw won't have any effect - have a look at a throttle body and manifold. The idle screw air channel ends up in the same passage as the IACV. So if the IACV is removed and replaced with a plate then the only adjustment is with the butterfly stop grubsrcew.

There is no idle screw on the top of the TB like other h22a TB's ive seen, where else would it be? Im almost 100% there is no idle screw, but i may be wrong.

[blizard]

Originally Posted by StealthCF4

There is no idle screw on the top of the TB like other h22a TB's ive seen, where else would it be? Im almost 100% there is no idle screw, but i may be wrong.

Does your throttle body look like this?



Someone stole ths idle screw

[nva2nd]

Coupe-R

Her car did do it before you tuned it as I drove it and the rev's held up between gear its horrible lol.

[doo0T!doo0T!]

Originally Posted by nva2nd

Coupe-R

Her car did do it before you tuned it as I drove it and the rev's held up between gear its horrible lol.

My H22a Eg used to as well and it was an OBD2a H22a still running the OBD2a ecu.
It was really weird first time I drove it but I kind of got used to it after a while, i thought it was just the big heavy flywheel and double balance shafts giving it heaps of rotational inertia that kept the revs up.

[Chaos]

Originally Posted by doo0T!doo0T!

My H22a Eg used to as well and it was an OBD2a H22a still running the OBD2a ecu.
It was really weird first time I drove it but I kind of got used to it after a while, i thought it was just the big heavy flywheel and double balance shafts giving it heaps of rotational inertia that kept the revs up.

yea its still doing that, i dont mind it though. probably used to it too, as ive only ever driven h22a cars

It would be interesting to see what the difference would be with a lightened flywheel however. might save up and do that when i do my clutch in the near future...

[doo0T!doo0T!]

Originally Posted by Chaos

yea its still doing that, i dont mind it though. probably used to it too, as ive only ever driven h22a cars

It would be interesting to see what the difference would be with a lightened flywheel however. might save up and do that when i do my clutch in the near future...

I'll have a euro R clutch and flywheel for sale very soon. (and a euro R box too you know you want it!)

[StealthCF4]

Blizard: Yep it looks like that, with the missing screw.

[StealthCF4]

Originally Posted by doo0T!doo0T!

I'll have a euro R clutch and flywheel for sale very soon. (and a euro R box too you know you want it!)

How much would the euro-r box be?

[Coupe-R]

Interesting, so someone really did steal the idle screw on that model
P.S I didn't know if you blocked the IACV the idle bypass air wouldn't go anywhere.

Good info, cheers.
So the idle screw port actually ends up at the IACV? Ignor the highlighted part thats the map sensor passage.
EDIT: checked a throttle body and manifold just then, yeh it does go through the IACV hole, BUT there is also a small provision for it past the throttle plate (I.E not through the IACV)
oh well the OP was screwed anyway cause someone stole the idle screw hah

Her car did do it before you tuned it as I drove it and the rev's held up between gear its horrible lol.

Never noticed it, however her idle was adjusted far to high, if that was any difference?

[StealthCF4]

Still looking for a throttle body with a fitv. I am wanting a type-s throttle body so that it can stay at 62mm.

Does anyone know what the throttle body size is for a normal blacktop h22a (it may be 62mm for all i know)?

And does the type-s TB have a fitv valve?

Most importantly will a fitv throttle body actually fit on my obd2 duel runner f20b manifold?

Doo0t! doo0t!'s euro-r box will be going in soon, as well as a lightened flywheel, so that may help the revs drop quicker anyway. But would still like to get rid of the hum, and be able to drive with cold starts.

[Vindots]

Stealth.. bro. im interested to have a look in your car!! im just a new honda owner. Ive got 1998 Honda accord SiR-T the same engine as yours and maybe those mechanical stuff around our cars. nice car mate! sorry if I interupt this thread. But your car is so mean!!!.. have a good day to everyone here! (this is my First reply/post i reckon)