I've been troubleshooting my 1999 Honda Civic D16y8 5spd for while now. It had the typical Honda surging idle when I took possession of it. Now I'm at the point where it doesn't surge (or rarely does) but does have a high idle.
On cold starts, it idles between 1300-1500rpms for a while before settling down, which can take quite a while (engine at operating temp.)
Things I've done :
New IACV and bled coolant
Plugs and wires
Distributer and engine timed correctly
Test coolant temp sensor w/ multimeter. All good
Test TPS with multimeter. All good
Idle relearn procedure. But maybe it wasn't done correctly? I followed the Haynes manual. It's possible I missed a step.
Checked for vacuum leaks using carb cleaner. All good. But MAYBE I missed something here.
Is there anything else I can look to? I know the idle should be higher on cold starts but should settle down shortly thereafter. Seems only when engine has been driven and properly warmed does it idle within spec.
The ONLY thing I can come up with is the idle relearn wasn't done correctly or didn't take or there's a vacuum leak I missed with the carb cleaner. Curious your thoughts on this common Honda problem

 

So, I don't have an answer. I only have an experience. I have driven my my 1998 D16y7 engine for 19 years daily (273,000+ miles on it). What you describe seems like normal operation to me. And in the Honda FSM you often get instructions to warm the car up until the cooling fan comes on before testing or setting one thing or another (like ignition timing). I think you did some great maintainance, but I am not sure there is a problem. Someone correct me.

 

Although this is my 1st Honda and what got me into them, it seems the idle should settle down quite a bit earlier. I suppose you could consider this : it is a 20 year old engine with 202,000 miles. I guess the only way I'll know for sure if this is "normal" would be starting the engine when it's 100° outside. I'll have to wait several months for that as I'm in NH.
I'd say confidently the idle is "a bit off". Like I mentioned, it was surging before (typical Honda thing) and now it primarily just idles high. I feel somethings amiss.
One test I can't recall if I performed was covering the throttle body while running to see if the engine chokes out and stalls. I'll be going this tomorrow.

 

I would watch your temp gauge to see whether the engine warms up slower than normal. If so, you may need to replace the thermostat.

 

Would the thermostat cause a higher than normal idle? I've never had overhearing issues. But taking longer than normal to reach operating temperature is something I hadn't considered yet. I'm aware a failed coolant temp sensor can cause idle issues since it'll send incorrect signals to the ECU.

 

A faulty thermostat that remains open too long will delay both the engine from warming up and the idle speed from dropping to normal because the engine coolant temperature is used by the ECU to control idle speed.

 

Clean the throttle body and use a new gasket.





eH.

 

I'm gonna replace the thermostat as a precaution. The darn thing started surging on me today. After driving it for a bit, at idle (stop sign), the idle surges. I thought I solved that. I guess not. I may attempt another idle relearn after the thermostat replacement. This thing is really kicking my but. Is there another procedure other than the one stated in the Haynes manual for the relearn process?
2 things I haven't checked yet :
1) The idle control screw. It's possible it's not adjusted properly. I've only recently purchased this vehicle.
2) Possible bad head gasket? I haven't checked the coolant for exhaust gasses but I'll be doing this soon.
So could a bad head gasket really cause surging idle and high idling?
Seems it was idling fairly well last week, although it did take a while for the idle to settle down. It idles high until reaching operating temp.
First up is the thermostat

 

Any CEL codes associated with the idle problems?

Regarding the surging, do this simple test:

1. Warm up the engine.
2. Remove air intake system.
3. Start engine.
4. With the idle surging, use your finger to cover the IACV bypass hole (upper port) inside the throttle.
5. Does the surging stop?

If so, I would recommend that you start by re-bleeding the cooling system. Also describe how this was done the first time.

 

[QUOTE=muellersfan;52088128]Any CEL codes associated with the idle problems?

Regarding the surging, do this simple test:

1. Warm up the engine.
2. Remove air intake system.
3. Start engine.
4. With the idle surging, use your finger to cover the IACV bypass hole (upper port) inside the throttle.
5. Does the surging stop?

If so, I would recommend that you start by re-bleeding the cooling system. Also describe how this was done the first time.


No CEL. How I bled coolant system was to put a funnel in the radiator cap and allow all air bubbles to escape. I did not loosen the bleeder screw however. Do the D16y8 's have this bleeder screw? I didn't notice.
​​​
I will be performing the test mentioned above tonight and report back shortly I'm stumped as of now but I'm hopeful it's a simple oversight (possibly still air in the cooling system)

 

Bleeding:
Your engine lacks a bleeder valve.
Turn heater all the way to max heat. No need to turn on blower.
Top off radiator with coolant.
Loosen radiator cap one turn.
Idle engine until radiator fan turns on twice.
Top off radiator and reservoir.

 

I also like using a burp funnel and pointing the front of the vehicle uphill, sloped driveway, jack stands, etc...

 

This method^ is preferred by many members, but following the method detailed in the service manual has always worked for me without making the additional funnel purchase.

 

I'm happy to report, after following the coolant burping technique mentioned above (thanks a million muellersfan, once again) that my idle surging has stopped! I've driven it only about 30 miles, but it idles beautifully now.
I still have, what I mentioned in the 1st thread, as a slightly higher than "usual" cold start idle where is also takes a bit longer than "normal" to settle down. Temps are freezing in my area lately (5-15° in the mornings). I'm putting in a new thermostat shortly to see if that has any effect. I've tested the TPS and CTS and all check out there.

 

This^ likely explains the higher than normal cold-engine idle speed. Hopefully replacing the thermostat will shorten the engine warm up time. I would recommend that you purchase the thermostat from the Honda dealer.

 

I purchased a Genuine Honda thermostat

 

I fixed my idle surge after trying 3 different iacv it was a pain because I kept checking everything took me about a month to figure out it was the iacv and to try different ones

 

Did you use a Genuine Honda IACV? I used a Genuine Honda IACV and have no worries it's not performing 100% as it should. As mentioned, it's critical to burp the cooling system properly to remove all air bubbles. I thought I had but it turns out I still had some air in the system.

 

ya I had too use the OEM IACV I did not wanna spend the 200 and something dollars but now I know that aftermarket ones don’t really work I tried two one from pepboys and one from autozone till I bought the OEM because I was tired of wasting time with it as soon as I put OEM I bleed the coolant and it was running perfect right at 800 rpm

 

You can usually fix an IACV problem by cleaning it with brake cleaner, assuming that the Ohm reading is to spec.

 

ya I did do that with the original iacv but cleaning it didn’t work so I went to pepboy bought one and AutoZone one then when they didn’t work someone told me to get a new OEM and put it on it went on my B16A2 and as soon as I put it on it worked flawlessly I think the ones from part store are for automatics but it say it works for Manuel’s so I think there’s a problem with the parts stores IACV

 

I don't know if this is the right place, but I have a 92 si with a d16z6, the idle surges after a minute or so and won't stop. There's no vacuum leaks, the coolant has been bled, I did the bleed procedure 3 times to be sure, it has a brand new tstat and a brand new fitv, I've ruled out the iacv, I've multimeter tested the tps and o2 sensor, I have no clue what it might be.

 

Wrong place. Create your own thread.

 

I have, nobody answers them.

 

Post a link to you thread.

It's impolite to post your car problem in somebody else's thread.