D15B idle

[eaphenom]

I recently swapped a JDM D15B into my '93 CX hatch. The JDM motor had a broken TPS and leaky IAC valve. So I use the parts from my stock CX motor, no problems. I had a few bolt-on parts on the stock CX motor that were switched to the JDM motor. FYI - both motors are naturally aspirated, and the swap was done by reptuable shop.

AEM CAI
DC Sports 2-piece 4-2-1 header
DC Sports muff

The above parts were switched from the stock motor to the JDM motor. I noticed both the stock motor and the JDM motor would idle around 650rpms. Which is too low. I read somewhere that the two motors should idle between 800-1000rpms. Someone on this site said Hondata told them that the optimal idle is 800rpms.

I was wondering if my idle has been lowered due to the fact that the motor/motors has/had aftermarket parts installed on it. FYI - the JDM has a 62MM Skunk2 intake manifold...and I am waiting on a 60MM throttle body from Skunk as well (which I have been told will not alow the FIT valve to be used anymore). Like I said before, both motors idle at/around 650rpms. Also, neither motor has/had a catalytic convertor.

There is an idle adjustment screw on the throttle body that is suppose to abjust the idle, correct? There is also a screw on the underneath side of the mechanism that manually opens/closes the butterfly, what is this screw known as?

I read somewhere in these forums that you are only to adjust the idle after first letting the motor reach normal operating temperature, then unplugging the IAC valve...problem...my motor dies when I unplug the IAC valve. There are some steps that follow, but since unplugging the IAC valve didn't work, I could not proceed any further. I am confused as to how to correctly adjust my idle. I want my motor to idle between 800-1000rpms...650rpms is too low.

Hope I haven't left any details out, feel free to ask any questions. I will check back later.

FYI - all sensors seem to be working correctly, as well as the FIT valve and the IAC valve.

[eaphenom]

This is a real hard one huh?

:confused:

[EGhatchintheham]

No, not hard at all. Just follow the throttle cable to where it is connected to the throttle body. There are two nuts on either side of a mounting bracket. Just adjust your idle there. Very easy.

[Cuong-Nutz]

I'd say adjusting the IAC via screw until you get the idle you want. I don't have the FSM on me to confirm so. Just mark it's current position and start tinkering until you get what you want. You might try searching honda-tech under low idle... Sorry, can't be much of help to you.

[bigbbass451]

http://www.homemadeturbo.com/forum/index.php?topic=12879.0

There's alot of info in this thread. Read through the whole thing and you'll probably figure it out.

[Tad]

mmm, I dunno, correct me if i'm wrong but 800-1000 is too high of an idle for that engine.

750 is about norm imo

[eaphenom]

Props for all the info...so you don't have a FSM handy, can you still tell me what the correct idle should be considering my motor is mostly stock. A post above said 750rpms.

I am eventually going to clean out the IAC valve altogether, but I want to wait until the Skunk TB is installed and all the vacuum lines are checked, seals etc. It just an annoying problem like others before me have said. Again thanks for the help.

[gearhead98]

yeah, 750rpm is the stock idle speed

[eaphenom]

Okay, my new IAC is installed and so is the Skunk TB. Motor idles high now, tach needle moves in step with motor when I hear the motor surge. Generally that means the ECU is telling motor to run rich...then lean out...then rich again...then lean out again, if there are no vacuum leaks present correct?

I do not have a FITV anymore with the Skunk TB, there are no vacuum leaks, new IAC installed correctly, TPS is within correct voltage.

The check engine light pops on after the car has been running awhile. When I turn off the motor, then start it back up, the light is off. I have yet to check the O2 sensor. Can the O2 sensor cause this type of problem? Again, I have a D15B with a 4-wire O2 sensor installed on a DC Sports 2-piece 4-2-1 header. I used this same 4-wire O2 on the stock CX motor I had before the swap. I have had this car since August of 2003, I have never changed the O2 sensor.