Hey I have a 00 Civic EX 5spd with an HMO Import D16YA (Steve said it was the same as the D16Y8 that was replaced ). Just got it on the road two days ago.

Everything started out decent. Upon first start it idled around 1500 rpms. No big deal, right? I read on here somewhere the ECU may need some time to learn a new motor. Went for a 300 mile drive up to Duluth. She was great on the highway. Once into the city, idling for a red light, it threw a CEL. Since out of town I simply pulled the backup fuse and let it sit for a bit. CEL was gone and drove it home fine. Once back in town had to wait for a train. While idling it threw a CEL again.

I reset the ECU again and drove it to work today. Halfway through the agonizing traffic it threw a CEL again. Once done working I drove it straight to Autozone for a code scan. The woman there plugged in the scanner and wasn't able to get a reading. I told her it wasn't the original motor, just the left handed Japanese version of the D16Y8. She said that's why she couldn't pull a code...


Read some posts on this awesome website about how the IACV can clog up. I took that off and it was very dirty. I cleaned all the carbon out (scrapped it, then used about a half can of carb cleaner) and let it dry. Reinstalled it and reset the ECU again. When the CEL is on, it runs like crap. Everything is really touchy and rough. Throughout all of this driving whenever the clutch is pressed in, or neutral, it will idle down quick to 1K, then climb back up to 1500.

Took it out again. Same thing, high idle. And just as before as soon as I was stopped somewhere idling the CEL would come back on.

So I jumped the service connector and go a code 14. IACV. Does this mean it needs to be replaced? Autozone is selling them for 170 . I've been searching this site for a while and can't find anything on a test for the IACV, only how to clean it.

I'm sorry for the long post. I just read these other threads where someone asks for help with their car and leaves so many questions unanswered. 170 is a pretty decent chunk of change for me and would hate to waste money on something I don't need.

Many many thanks!
Norbster

 

If you pull the plug on the IACV start the car and it idles down while throwing a CEL does that mean the IAC is bad? That's what it's doing.

 

Code 14 indicates a bad IACV, bad IACV wires, or a bad ECU. Here's how to troubleshoot with a multimeter:

 

Yes! Thank you RonJ. I will try this procedure tonight and let know what happens for other people.

 

Heh... It looks like the IACV is fine, passed the test... It's just that the intake manifold gasket is leaking, like a sieve.

If you put your ear up to the intake manifold where it meets the ports you can hear a hiss. That same hiss will persist for a moment after the key has been shut off.

I tried tightening all of the bolts more. That didn't help it any. And spraying carb cleaner right where the IM meets the block makes the engine struggle...

So, if that's a brand new one on there what can I do? Double up? Anyone ever have an IM gasket leak? Does that sound like the right symptoms?

 

Sorry, I should have recommended that you pull the CEL code with an OBDII scan tool. The code would have come up P0505, one cause of which is an intake air leak. I therefore posted the wrong troubleshooting diagram.

Is the leak from the IM or TB gasket? In either case, torque the bolts to spec.