bgarrett7

So, here's the situation...

I've got a '99 Civic EX that I've had to replace the engine in twice now. As an admitted novice, I'd say my knowledge of cars lays somewhere in the "knows enough to get by" range. Needless to say, the guy who I had put in the latest engine a couple weeks ago, I don't really trust as far as I can throw him.

Ok, the problem...

The first engine replacement was about three years ago, engine was from a salvage yard, so I can't even really verify it was the correct engine in the first place. The thing I do know about it is it lacked the IACV. From what I've read about the legit engine in question (D16Y8), it's supposed to have an IACV, correct?

Well, when the new engine was put in -- this one from a more refutable place, a local engine importer -- it had the IACV and the guy putting it in didn't really know what to do with it (ie: what electrical connection, etc).

So, right now, the IACV currently has no power going to it and my tach is all over the place. When the car is cold, the car idles in park around the 2000 mark; when it warms up, it jumps from between 1000 to 2000. When put in drive, it runs fine as long as you're giving it gas, but the second you let off, you can feel the car kick back and the tach will drop considerably. It runs especially inconsistent in stop-and-go traffic, at times making me wonder if it's going to stall.

Both the mechanic and I have looked around under the hood and don't seen any possible connections from which the original IACV may have been connected, had there been one in the original to begin with. Like I said, the stock engine is long gone, and of course, I can't say whether or not there was one on it or not. I've seen the second engine and there definitely wasn't a IACV visible on it, however, I never received any type of check engine codes related to it while that engine was installed.

I took the car to Autozone right after the latest engine was installed and the only code it was spitting at that point was a P0505, which relates to the IACV. However, after taking it back this morning to see if any others have popped up, I've now got P0108 ("sensor circuit high voltage"), P0420 ("catalyst system efficiency below threshold") and P0122 ("TP sensor 'A' circuit low voltage") showing up, along with the P0505 (which is now "pending"). Are they all related to the initial problem, or has more damage been done because of the initial problem?

I've since taken the car back to the mechanic who put the engine in and he's still dumb-founded by it, so I'm pretty much written him off as being any help. So, what should I do?

delsolproblems

There are two main types of IACV- a rotary IACV and a linear one. They use different connectors. The linear has a 2-wire connector and the rotary has a 3-wire connector. Make sure you have the correct IACV, both for your motor and for your harness connector.

bgarrett7

From what I can feel on the IACV itself, it feels as though there is a connector on it for a 2P connection -- so, two-wire, perhaps?

delsolproblems

Oh, and your other codes are mostly if not all related to the IACV situation. The IACV on your AT motor should be on the bottom of your throttle body. It should be a rotary with 3 wires.

bgarrett7

So, here's the location of the IACV, is it right for AT?







And what of the lack of any sign of the actual electrical harness for the IACV?

bgarrett7

Hrm... Anyone?

mark11017

you have a 2 wire iacv, on the tps sensor on the throttle body there should be an additional harness that runs along with the tps harness. make sure that connector is plugged into the iacv.

mark11017

hope this helps ..

follow the tps harness down to the iacv harness they run in the same loom together

drocha86

first take off your throthle body underneath the throthle body there is a 3 pin connector to your iac valve it connected to the throthle body and all you do is dissconnect the coolant lines and the3 pin connector and the 2 or 3 bolts that hold it on its about 90 bucks at autozone (which i dont reccomend but hondas prices on this part are outrageous so i do reccommend) and the and what your pointing to in your pic is not the iac its the fast idle valve

mark11017

99 honda ex have a 2 pin iacv, non vtec has a 3 wire. he has a y8 thus having a 2 pin connector my diagram is correct. the FITV is located under the throttle body.

Sic_DA_Nine

automatic y8 has a 3 wire on tb.
so it all depends if your ex is a 5sped or auto

bgarrett7

Ok, here's a better (hopefully) shot of my engine...



Alright, so, this is the TPS sensor?



And here's the view from just over the IACV, tracing the harness...



The additional harness currently runs here...



The whole harness connects underneath and wasn't able to get a shot of there.

I also wasn't able to get my camera underneath the IACV to get a shot of the connector, but was able to get my cellphone, so here's a crappy shot that shows a 2-pin connection on it...



So... What now?

mark11017

carefully unclip the tps connector from the tps and gently pull up on the harness dont yank on it. trace it down (a few inches its not far away) till you find 2 wires that split off from the tps wires, those 2 wires are for your iacv

mark11017

also is this your old harness? is it possible that someone may have cut the iacv off of it ?

Rsporty

I don't know if this might help, but...
I have 2 Y8 intake manifolds.
One from a '99 5 speed and one from a 2000 automatic.
The one from the automatic DOES NOT have a IACV mounted on it.
The blank space is there, but there are no holes drilled into it. Not for the holes in the IACV or for the bolts to screw in to.
Is it possible that the automatic has no IACV at all, or is it just mounted somewhere else?

Rsporty

OK. I found it!
The IACV IS in a different place on the Y8 automatic.
Here's a diagram...

colley

Grrrrrrrr Hello i have the same problem. I can,t find the plug its just not there if someone has a wiring diagram maybe we can splice one in to hook up the iacv