pissedoffsol

Fixing an Erratic Idle

By: Adam Pilchack

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 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

pissedoffsol

addition:

Mr X489: hey pissedoffsol..... I read hondaswap's tech and reference's quite a bit....... and recently I had a erractic idle ( idle surge) and I tried all of ur solutions on there, and none of them worked.(im not saying they don't work... just not in my case) I ended up finding out the problem was with my fast idle thermo valve, and the little plate on the back that is closed off needed to be removed to tighting a valve back tight..... and that fixed my problem immediately...... I'd just thought I share this with you so you could possibly add this solution. But keep up the good work, if you need details my name on there is MrX or you can put me on as your buddy and talk to me whenever i come online. thanx

pissedoffsol