Hello all.

Car is a 2000 Civic Hatchback, all original motor/manual trans with no mods (until I messed it up). The car was a sweet pick-up at $2,500 all original panels, with the stock factory VIN on every panel including the front and rear bumpers. Even the glass had never been replaced. Pristine interior.

The mods are as follows:

GSR rear discs
Poly bushings throughout
ITR rear sway
No name rear tie bar
Skunk2 Alpha control arms
Ground Control coilover sleeves

Okay. Here is where I jacked things up. I had a nagging exhaust leak that I finally decided to find, turned out to be right at the base of the cat, on the header. My buddy had a no name brand new header, so I swapped that on while I went to get the cat/header welded. Upon return to the house, I went to install, and discovered my bottom radiator mount/tab was broken... Off to the junkyard I went.

While there, I found a four door EX (96-98 model) auto sedan. I scored the intake manifold and throttle body for $5.

Here is where things got jacked. Before starting the intake mani swap, everything was perfect with the idle. Anyways, I took the rotor from the EX throttle body and put it on my D16Y7 throttle body so it would face the correct way. I ordered a Y7 intake mani gasket and a Y7 throttle body gasket, and proceeded with the swap.

Once I got it all buttoned up, my idle (while cold) bounced between 1k and 2k rpm. Once warm, it had a rapid bouncing idle at 1500 rpm. I took out the IACV and cleaned it well, and reassembled with a new gasket... still had the same idle issue. I quadruple checked every connection, and can't find a damn thing wrong, and no vacuum leak. I have a voltmeter to check readings for sensors, but have no idea how to use the damn thing (has a digital readout with a ton of options on the dial).

It sounds like there is a vacuum leak, right at the center of the intake mani, but it comes from underneath. I checked all the connections with a camera under the mani, but found nothing that appeared out of place.

I have searched, and read a ton. In the past hour, I decided to go back in the garage and tackle whatever it could be. I started the car, and started unplugging, then plugging back in sensors. I even adjusted the idle screw on top of the throttle body to see if that had anything to do with it.

Now it idles at 1500 rpm consistently (smells like it is dumping fuel now) but when you hit the throttle only bounces at 2,500 rpm rapidly and won't go any higher!! I plugged everything back in and still is jacked up.

I feel like I ruined a perfectly good situation, all because I wanted to start shopping for boost and new I needed an EX intake mani. It was too good a deal to pass up.

PLEASE HELP!

 

Cliffs would help.

 

Idle either sits at 1500 and won't go above 2500 rpm at full throttle, or bounces between 1k and 2k rpm.

 

Post the CEL codes.

Look for swapped sensor connectors.

 

Can be a lot of things...
Do you have the MIL light on? Any codes? Check for that.
Did you connect the PCV valve?
I think just the 99-00 ex had EGR...
Sometimes the MAP sensor and idle valve have the same plug.
Did you put the injector o-rings; the ones that goes on the intake manifold not the fuel rail?

 

Exactly!

If the car don't pass 2500 rpm you should have CEL code. Don't connect and disconnect sensors like crazy because you will throw more codes.

Also MAP and IACV connectors are similar if not the same.

 

I am willing to bet the tps and iacv plugs are plugged in backwards....there could be a vacuum leak as well but the 2500 rpm rev limit is because these are plugged in backwards...I just bought one with the same swap with the same issue about 2 months ago!! Steal for me sorry for them good luck!!

 

Did you do the manual conversion to the manifold? 2 wire iacv, manual tb, and recalibrate tps?

 

Three wire IACV is what you would want if still using the DX / LX non-VTEC engine and ECU. You're going to have to revisit this if you ever want a full EX conversion, i.e. VTEC engine. Because the ECU for the manual EX with VTEC uses a 2-wire IACV and all the others use three.

Like others mentioned, plugging the harness plugs wrong is easy to do, as they are not mechanically "idiot proof" keyed like on most other cars. You have to look at the wire colors to be sure the proper plug is on the proper part.

Anything letting extra air into the intake will make it idle high. But that will not affect revving up and driving, so check the sensors first.