Another Hunting Idle Problem (I am cursed)

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CAFROG

CAFROG

Honda Minion
VIP
Sometimes......I hate driving my car!

Here's the situation: (B16A w/CTR cams and bolt ons in an EH3)

With the motor up to temperature (never does it cold) the idle hunts after acceleration and goes back to normal idling after 5-10 seconds of hunting. No codes at all.

What I've done:

Cleaned the IACV (which wasn't dirty to begin with)
Bought a new OEM FITV (torqued to TB @17lbs)
Switched TB to one with a for sure "good" TPS on it
Unplugged the IACV at running temp and the idle didn't move (Helm says idle should go down or car dies)
Reset the ECU
Burped/Bled the coolant system after doing the FITV

What I figure it "might" be:

The USDM P30 ECU is faulty.....? (I dont think so)
The IACV is bad (torn between a junkyard find and spending the $200 for a new one from Honda)
Could I have a vacuum leak? Don't feel or hear one but maybe someone has a tip to help me?
My gut tells me its the IACV and FITV fighting eachother

Let me know any thoughts you might have!
 
Was at a friend's shop today and he has a 95 Integra LS with a blown head gasket so I checked out the IACV on it.....sadly, its different and wont fit my B16 IM. Does anyone know what Hondas IACV are the same as my OBD1 B16? 99/00 Civic Si? Any VTEC from 92-01?? I figure the GSR IACV is the same. Does OBD matter? Any info on the interchangeability of these IACV's would be appreciated. I think I'm going to hit up the Recyclers in Sacramento.

I also noticed that the idle will not hunt with the A/C on but goes right back to hunting if I shut of the A/C

EDIT: From the info I have read up on, 99/00 Si does not fit it. I think the only ones that fit are OBD1 B18C1 and OBD1 B16A3 (or their non-USDM OBD1 versions)
 
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I fiddled with it this morning. Read my Helm Manual and it said to get car to running temp and (while the car is running) unplug the IACV. It was the idle should drop and if it doesn't, then they recommend replacing it. I unplugged it and the idle fell like its suppose to (which pissed me off b/c I was hoping this would be the problem but its not). I then adjusted the idle speed like the Helm manual said (which is at running temp with IACV unplugged then adjust the idle adj screw to get rpm to around 500rpm). The motor is acting much better. Drove it got it hot and let it run for a while with no hunting.

I don't think I'm out of this just yet. It acted really nice after I installed a new FITV to only have it go back to pissing me off a few days later. If it starts hunting again, I think my next step is taking it to a mechanic to do a vacuum test. I don't know how to do it and figure it takes an expensive tool i do not own. Plus I am getting burnt out on this whole situation!

No input from anyone??
 
before you pay a guy to do it.
while the engine is cold and running, take some carb cleaner and spray around the intake side.
if you have a vacuum leak, it will suck the carb cleaner in and you'll hear it from the engine bogging a small bit.
dont do it while the engine is hot, it would most likely combust.

if you dont feel safe doing that,
let it warm up all the way, pull it into a garage or somewhere where the air is still (keep the door cracked or open for the exhaust fumes.)
bum a cigarette off of somebody, take a puff, dont inhale it, and blow it around the motor, if theres a vacuum leak you'll see the smoke get sucked in.

i doubt that you'll find one since you cant hear one, and if there is one i doubt that it is big enough to affect engine performance like that.

just post if it starts happening again, and we'll go from there.
 
I am having the same problem so In for the read. I am in the process of figuring out my problem so I will let you know if I find something that you haven't tried yet.
 
i would say to first start off with the easy maintenance shit.
clean the throttle body, metal expands when warmed up, and if theres extra crud on there when it does it may cause the computer to overcompensate until it gets it right.
run some sea foam through the intake to clean the shit out.
check your spark plugs.
double check to make sure all vacuum lines are connected and connected properly.
 
Ones I have checked:

brake booster
charcoal canister to TB
charcoal canister to Evap Purge
fuel rail vent to back of IM
Last winter I put a B16A3 IM, ECU, Evap Purge and OBD1 USDM B series TB
I Carb cleaned it all before install with Hondata gasket torqued to roughly 17lbs and re-tightened the next day (after driving/expansion).

When I went to smog...it didn't pass so I ran sea foam through the gas tank (figured the IM was clean but maybe the piston heads/cylinder walls had carbon build up)
New cat and Bosch O2. I then had the great idea of raising my idel speed so I adjusted the flat head screw on the TB. This is when I hunting issues began. It hunted a bit when it finally passed smog.

Now that I know how to adjust idle correctly....maybe this was my problem?

None of those hoses seemed to be making nose or had rips. I was thinking it wasn't a vacuum leak too but I just don't know. It seems to idle much better now but I drove it for 30 minutes on the highway and (once I pushed the clutch in) it hunted twice but caught itself. Other than that, its been much better. Going to have my timing checked soon. I know a shop that will do it for cheap or free. I'll talk to him about a possible vacuum leak and see what he says. I'm contemplating selling the swap and going with a USDM B18C1 that I'll refresh with new bearings, rings, studs, head bolts etc. Just want it running right before I think of finding a B18C1
 
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check the pvc?
most honda people dont.
its such a pain in the ass to get to that a lot of people like to imagine that you never have to replace the damned thing.
its under the intake manifold. its a bitch.
 
I have been thinking about it. Its a cheap part and its a smart move....but it does seem like a pain in the ass. Would have been easier to do it when i swapped Intake Manifolds!

Have you done one? Suggest going from the bottom? Seems like a bitch all together.
Doesn't it plum through two runners? I pinched it and heard/felt nothing
 
No....I SHOULD have changed it when I swapped Intake Manifolds. But I do remember blowing through it and it was clear.

I think this problem all started when I swapped TB's. I think I should have adjusted the Idle correctly and maybe I wouldn't have had this problem in the first place.

Drove it out of town last night and the idle never hunted. So far....so good
 
CAFROG i had this problem when I put a LS TB on my Y8 intake turned out it was the TB after all so I put the stock one back on and it ran fine. Your problem is deffinatly a vac leak, and I adjusted the idle screw and it helped a little bit but had to high of a idle. I would find a good tb or try the brake fluid test thats how I found my leak it is a good test. try this and let me know.
 
hondafreak513 said:
CAFROG I would find a good tb or try the brake fluid test thats how I found my leak it is a good test. try this and let me know.
Click to expand...
I already switched back to my JDM TB and it had no change. It hasn't hunted for the last 150+ miles. Only complaint is it will idle pretty low when its nice and warmed up (650-700rpms). I'm afraid if i lift the idle up....it will hunt again.

Brake Fluid Test? I will need to look into that.

EDIT: Gonna try a soapy water technique I just read about.
 
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brake fluid test? wtf is that?

and thats really not that low for the idle. if i remember correctly, hondas are supposed to idle at 750+/-50.
wouldnt hurt to bump it just a bit, but i dont think there is much issue to leaving it where it is.
 
My bad I meant Brake cleaner I was really tired when I wrote that. Well if its idling fine now then give a while and see if it changes. I know my leak was from a plate in place of the fitv but brake cleaner does work great to find a vac leak. but thanks for pointing out the brake fluid I saw that the day after I wrote it and laughed my ass off but I couldn't edit it so ya you know......
 
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