i just finish my ls swap in my crx. the problem is when i start my car the idles at 3,000-3500. this happens if i dont start it for a couples of hours but when it gets warm it drops to about 1000-1200. how do i fix this? does my charcol canistor(sp) need to be hooked up?

 

ttt

 

Fixing an Erratic Idle

By: Adam


Let me give you some background on my del sol if you haven't been around long. It will be a year ago in March that I put my JDM B16 SIR II into my del sol. Since the day it went into the car, it would not idle correctly. There was always a surge. The following is a list of steps I took to cure my idle problem.. it took me just shy of a year to get it to work properly, but it's done!!

1) Check the voltage on your Throttle Position sensor. Sometimes when doing swaps, you have to use your old throttle position sensor because the one that came with the swap is almost always broken. The Honda ECU looks for .5 volts when the throttle blade is closed and 4.5 volts at wide open throttle. You can measure this with the aid of Hondata or an Apexi Vafc, or a handy old voltmeter.

2) Unplug your Idle Air Control Valve (IAC), which is located on the back of the intake manifold. Doing this SHOULD cause the idle speed to increase if it functioning properly. If it does not increase, then you have found your problem... go get a new one. If the idle speed does increase, begin to turn the bypass screw on the throttle body and bring the idle of the car down to like 500-600 rpm, then plug back in your IAC valve. This should bring the speed back to a normal 800 or so rpm. In the event that doesn't work...

3) Check your ignition timing and make sure it is at the stock spec. Usually 16*... see my article on cam timing.

4) Chances are now that you have a vacuum leak somewhere. Trace all of the vacuum lines and make sure there is no leak anywhere. Some people use a little bit of lubricant and spray it on the hoses to watch for bubbles. Personally I have never done this; so try at your own risk. If it still doesn't idle properly, keep reading.

5) Did your Throttle Body get bored out at all? Is Air bypassing the blade?

6) Another thing that sometimes causes cars to idle poorly is too much fuel. Do you have a Fuel Pressure regulator? Make sure that it has a vacuum reference and that it is within specs at static idle. Honda recommends 30-38 psi. So anywhere within there would be worth a try. To adjust your pressure at static idle, Hondata suggests that you do it without the car running. Turn the key to "ON" and the fuel pump will prime the system, then you can adjust your fuel pressure accordingly.

7) At this point I began to think it was my ECU causing the car to run poorly. I was running a p28 chipped with everything under the sun.. I had it all: skunk2 , mugen n1, jun, visions, spoon... all those reburned programs you can buy. None of them seemed to work. I looked into Hondata. Hondata is the savior of my idle... or so I thought. Apparently no one told me this, but Hondata had a problem running B16's with p28 ECU's for some reason. Well after several attempts of having new programs made that ran more lean at idle and generally just wasting my time... I found a lonely sole in Minnesota who had what he claimed was the magical map that fixes the p28/b16 idle problem. He sent it to me... I took it to Tom Payn at http://www.PaynTechnologies.com and had him write the program to my ECU and presto it's run great ever since.

The above is just a short list of possible things it could be ... but they are all things you can undertake without paying someone else to do it. Good Luck and if you need the hondata idle fix, or have any questions please email me: Pills@hondaswap.com

 

Overall a good post, but I have a problem with the above part of it. Unplugging the IACV should cause the idle to DROP, not increase. The base idle is set with the air bypass screw. Plugging in the IACV then allows the ECU to do it's thing and raise the idle to where it belongs, assuming it was low enought to start with. (ie: no vacuum leaks or bad FIV.)

 

what happens when i unplug my IAC and nothing happens?

 

one easy way to tell if your idle valve is working is to unplug it and when you plug it in your intake will make a bluump sound, if you cant hear that then you have to do some good ol' fashion diagnosing. gl