88 crx si, stock.

When my CRX gets warm, or hot, the idle fluctuates, but generally stays at or around 2k.

The only thing I've been able to do is unplug the IACV for it to go down.

So I replaced the IACV with another one, cleaned it, and it made the car idle better and lower, but it still idles high and it still goes down when I unplug the IACV.


I've searched and searched and can't figure it out.

WHAT causes a car to idle this high after warm up?

Quick facts: My radiator fan doesn't work and I'm still in the process of troubleshooting that.

And, I believe I have air bubbles in the coolant system, so I'm gonna bleed that soon.

Also, there are defniitely no vacuum leaks, and the throttle cable is definitely not stuck.

There is no erratic idle. This is constant at 2k after warm up.


So the big question is: If it's air bubbles in the coolant, why does the idle go down perfectly when I unplug the IACV?

Bad wiring on a completely stock unmolested harness? Bad plug? Another Bad IACV?

Please help! I don't wanna blow up this engine, I just swapped it in and it's my only CRX!

 

i just fixed this problem last night. i was surging and high idle. it is most likely the mech iac which is located on the bottom of the throttle body. this is what you need to do. take the tb off, along with the iacv behind the manifold. you need to bypass that mech iac. get a hose long enough to connect where coolant goes in the bottom of the tb and out the iac thats attached to the bottom (so nothing goes through it). your only going to be rerouting one hose. the longest hose that goes to the iacv needs to stay in place. use another longer hose to basically replace what was used as an exit for coolant on the mech iac into the block...and attach it to the other part of the iacv.

sorry if its a bit confusing..but it fixed my problem.

 

I dunno if that's gona help me since I got rid of all the coolant lines and ran one directly from the coolant housing to the intake manifold, bypassing the TB and IACV...

 

You don't have coolant lines going to your IACV?

Air in your coolant lines can cause the IACV to malfunction. It could also cause your fan not to function properly.

 

put it back to normal and see what happens

 

Before I try to bleed the coolant line, should I flush out the cooling system first? I feel like it needs to be flushed out..

I tried bleeding it today at break, and i got a lot of bubbles.

 

try to put a cts (coolant temp sensor) and that could solve it it worked for me

 

if you unplug the EACV, the idle should drop to around 500-600 rpm and remain steady - if it does, then it is probably not the EACV - you will also get a Check Engine Light and a code 14 - once you reconnect the EACV, you need to reset the ECU to clear the code

the 88 Si also has a dashpot control solenoid on the firewall for cold starts - when the engine coolant is cold, the solenoid opens the throttle plate slightly through vacuum from the solenoid to the dashpot, to increase idle slightly

bypassing the coolant lines to the throttle body and EACV is a terrible idea, if you want it to run correctly - Honda put those lines there for a reason - the coolant line to the throttle body has nothing to do with the idle rpm

 

honda put alot of things on there cars for a reason, doesnt mean it needs to be there...

 

that may be true on some occasions, however it is not the case for the iacv. coolant needs to run through it for it to function and maintain a proper idle. end of story

 

i disagree

every build/wire tuck i do, those coolants lines always get bypassed and theres never been an idleing issue yet.

end of story

 

If you have bypassed them already then you gave given up on warm up idle and acc. load from electronics. Now you might as well take a couple pieces of pop can about 1"x2" and unbolt the iacv and install your pop can block off in between and rebolt, then the mechanical one on the bottom of the throttle body the same thing. Leave the iacv plugged in then poof no idle problem and no cel. If the idle ends up to low you can use the screw on the top of the throttle body " not the cable adjust stop " the brass big counterset one that aims toward the passenger side and squeeze a little idle before you breach the tps start position and need to re-adjust everything. My mind reading expertise tells me a friend told you that those water lines are not needed so you listened, now at this point you are worried about the long run and want it all right, it cannot be both ways decide FULL bypass or fix it stock. Simple as that.

 

Well The Hooligan is my brother so... haha.

I actually only bypassed them once, for ease of swapping IACVs. I prefer it to be stock, and the Hooligan (my bro) can vouch that I wanted to keep it stock. I'll re hook up the lines and see what I can do.

But to be fair, my last setup with a y8 intake mani, i bypassed both TB and IACV coolant lines and never had an idling issue in 3 years.

It seems like bleeding the coolant lines yesterday did help a little bit, but the problem persists.

 

You haven't done that many builds buddy, and you've only done two half-assed wire tucks.

Pwned

 

lol, go fix your idling issue toolbox

 

whatever you say chief

 

hey i have a 91 ef with a jdm b16 swap...my car berly started doing this i turn it on at cold start up an idles at 3rpms then after warm it ildes around 1500rmps and 2000rpms....do u gguys have any idea what it can be???

 

 

There is a specific sequence to correctly set your idle speed.
http://i88.photobucket.com/albums/k1...lespeedSTD.jpg (STD models)
http://i88.photobucket.com/albums/k1...speedHF-Si.jpg (Hf/Si models)

The only purpose of the coolant lines to the throttle body and IACV are to prevent them from freezing and seizing up in really cold weather. The IACV is controlled by the ECU, and does not need coolant to function correctly. I have had coolant bypassed on my TB/IACV for several years without any issues, but I live where it is hot year-round.

IACV Coolant passage only transfers heat, does not mechanically alter operation of the valve.




How to test FITV: https://honda-tech.com/forums/honda-crx-ef-civic-1988-1991-3/how-fix-your-idleing-woes-fitv-iacv-2153910/
The FITV does use coolant to regulate cold idle. You can check if the FITV is the problem by removing the intake and covering the hole for the FITV with your finger. The FITV can definitely be eliminated.

 

You didn't accidentally swap the connector for the EACV with one of the other random connectors did you?

 

I've flushed my coolant, and I'm 99% sure that air in the coolant isn't it, but I do have to say when filling up my coolant it bubbled a lot.

Blown head gasket? Bad water pump? Car shows no sign of overheating, but the coolant bubbles a lot when filling it up.

When I unplug the EACV, it drops down to 500 rpms and idles fine. Plug it back in, check engine light, goes back up to 1,000 rpms, then eventually jumps up to 2k.

On my way home, the car would idle around 2k, and by the time I got around the block from my house, it would exceed 2k, bounce up and down from 2,000-2,300 a few times, then settle back at 2, sometimes wanting to get up to 3k before I shut it off.


I'd just like to say, that I put this 100% stock engine in the crx about a month ago and this problem has persisted through:

-Replacing EACV
-Removing coolant lines to TB and EACV
-Removing the dashpot because I never used one before
-Cleaned the throttle body
-Seafoamed the engine
-Flushed/Bled the coolant
-Checked proper voltage on TPS
-Confirmed no sticky throttle cable


I've never had this problem before. If it was a vacuum leak, I would've had it fixed the night I first dropped the engine in.

This Engine does NOT have a FITV, only one hole in the throttle body entrance.

I'm running out of ideas. The only thing to my availablity that is left to do is swap ECUs, and swap fuel pressure regulators.

NEVER have I had such a hard time with a completely stock crx. I've done swaps, vtec heads, y8 intake manifolds, etc etc and made them all work perfectly. It's so loud and hard on the engine that I have to leave it in gear at red lights, hold down the brakes, and let off the clutch until it idles at 1,000 rpms, then let off when I'm ready to drive.

ANYONE?!!? Cause I'm getting ready to go buy another intake manifold, possible engine soon haha.

 

When you unplug the IACV the idle is supposed to drop to about 500rpm.
It is really important to follow those idle speed setting instructions above ^ exactly. Did you do that?

Thinking Outloud*
Technically it does sound like a "vacuum leak" in the sense that air is probably leaking into the intake track "somehow" and is probably not fuel related. It could be something random like the check valve on the brake booster, or a loose or missing idle speed screw - you will have to check everything with the carb cleaner test. It could be the IACV. Test with one you know works and maintains idle to be sure.

 

thanks man

 

have you tried a throttle position sensor