I have a 95 Civic with a D16Z6 and an automatic. I decided to change the spark plugs and clean the IAC valve today (had a bit of a rough idle I was hoping to clear up) and now the car will barely start, and when it does, it won't idle without dying. However, if I can get it started and hold the accelerator pedal, it will run just fine, no misses or anything.

Here's what I did to clean the IAC:
Took the two bolts off.
Unplugged the connector.
I left the two hoses attached (they wouldn't budge when I tried removing the hoses), and sprayed TB cleaner into the two openings.
Let it dry for about half an hour.
Hooked everything back up.

Is there something I'm missing here? I ruled out it being the plugs since it revs and runs fine if I give it some gas. The IAC itself looks pretty clean, and the gasket still looks pretty good too.

Thanks in advance.

Edit: Here's a picture of it as it sits right now:

 

Have u look around the vac hoses? Maybe u might've knock something loose?
Reset ecu. Try again.

 

I went out and checked all the vacuum hoses and everything was hooked up correctly still.

I sprayed the IAC out again, this time with MAF cleaner, and let it sit a bit longer and then sprayed some compressed air into the IAC to make sure it was dry, and hooked it back up. I also disconnected the battery for a while to reset the ECU. After all that, the first start was pretty rough, but now it seems to be able to idle again without dying. The only thing is, the idle is much lower than what it used to be. The tachometer doesn't even register anything when it's warmed up and idling, so it seems to be idling under 500 rpm then. Is this normal?

 

I would drive it a day or 2. Let it burn through everything. Then check again. If need be, you may need to adjust the idle screw to gain a little more rpm at idle. 750+/-50rpm is normal..

 

Use this link. Another h-t member help me with this link.
picture_4760.jpg Photo by RonJ_HT | Photobucket

Also, try this first.
http://my.prostreetonline.com/2014/1...vice-your-iac/

 

Did you put the spark wires back in the correct order?

 

Thank you for the links, those look really helpful! I'll drive it around for a day or two to see if anything changes first.

Yep. I did the plugs one at a time, so no chance that the wires were mixed up.

 

You should check timing with a timing light. Wrong timing of course causes various runnability problems.

The first link is for a 1996 or later with 3 wire IACV so it really doesn't apply to your car.

IIRC, adjustment procedure for 1992-1995 is as follows:

Warm up the engine. Confirm that the CEL is not lit. Turn off lights, heater, A/C etc.
Unplug the IACV and set the air screw for about 450 rpm-- which is running slower than normal idle but not stalling. Do not turn the throttle plate stop screw. The adjustment is the flat-head screw valve in the top of the throttle body. It is a good idea to first completely remove the screw and clean the passage with spray cleaner, because it accumulates the same black gunk that the IACV does.
Reconnect IACV and a normal idle should pick up. Unplugging the wire while running will turn the CEL on with a code 14. Clear the code when you are done adjusting.

 

Ah, I think you're right about that being for the later models. I was able to track this down from the FSM for the 92-95 civic though, so I'll just follow that:

Idle

And I'll have to get a timing light so I can check that.

Thanks!

 

An external tach is needed to set the 450 rpm base idle speed.

 

Yes don't count on the stock dash tach to be very accurate below 1000 rpm. Or any rpm for that matter.

 

Would a timing light with a tachometer function be suitable for the external tach, or should I look into something else as far as that goes?

And has anyone else ever ran into having their idle speed change after cleaning the IAC?

 

Yes

 

I stand corrected. My apology for posting wrong info. Hopefully you can get it resolve soon.

What spark plugs did you get, and did you gap them accordingly? Unless it's iridium then no gap required.

 

No worries!

So it turns out, this statement explained my low idle problem. I hooked up a timing light before adjusting anything, and what do you know, it's idling right at 700 rpm just like it should be. Funny thing is, before I cleaned the IAC, the tach showed exactly what you would expect it to for a ~700 rpm idle. Must have actually been idling higher than that.

Thanks for the help everyone!

 

The Tach STARTS at 500rpms

 

More like "unless it's iridium, in which case you're just doing it wrong." OEM specifies copper for a reason. Stick with the proper copper plugs. Don't use any unnecessary fancy ****.

 

I still run copper per OEM spec.
Don't know if OP is running the same or not.. Just figured I asked.