Fixed the damn idle surge! IACV surging idle
08-11-2007, 11:59 AM
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Fixed the damn idle surge! IACV surging idle
Setup (not like it really matters)
JDM B20B (97) converted entirely to OBD2B for my 99 hatch (running a stock PHK ecu)
So I did my swap and noticed that the car hated having the IACV hooked up. No matter what ECU I had in there, it would surge. Really annoying as some of you may know. I tried opening the thermal valve, and screwing in the screw (which was already tight), I tried everything. So eventually I just took a piece of plastic and madea plate to sandwich between the IACV and the intake manifold. Living up north it was always cold, and without the IACV hooked up it would idle REALLY low in the morning when i'd crank it up. So I had to back my idle screw out pretty far to get a decent idle.
Now that i'm down in the south, I had to hook up my A/C because its hot as ***** down here. Well the IACV controls the idle when its on, and my car was idling at like 300 causing havoc on the A/C. So I had to unblock the IACV so it wouldnt die with the A/C on. Well immediatly the idle surged. Especially when i'd first turn the car on in the morning. It would immediatly idle at like 2300rpm, then surge between 1500 and 2000 until I drove it around a little. Then it would calm down and do the 1000-1500 surge. I was throwing check codes for the IACV left and right....but I had A/C. Well one day when I was tooling around under the hood, I noticed that my idle screw was out quite a bit. (from when I had the IACV unhooked).
Just for ***** I closed the screw all the way, and then backed it out maybe half a turn. I reset my ecu to get rid of the light. Cranked the car up...NO SURGE AT ALL!!!
It appears that having my idle screw out so far was causing a vacumme leak. The screw wasnt out so far like it was going to fall out, but it was about flush with the face of the throttlebody. I'm now happy, with no surging idle, and my car idles rock solid with and without the A/C on.
So if you have a surging idle, I suggest you at least check the idle screw.
JDM B20B (97) converted entirely to OBD2B for my 99 hatch (running a stock PHK ecu)
So I did my swap and noticed that the car hated having the IACV hooked up. No matter what ECU I had in there, it would surge. Really annoying as some of you may know. I tried opening the thermal valve, and screwing in the screw (which was already tight), I tried everything. So eventually I just took a piece of plastic and madea plate to sandwich between the IACV and the intake manifold. Living up north it was always cold, and without the IACV hooked up it would idle REALLY low in the morning when i'd crank it up. So I had to back my idle screw out pretty far to get a decent idle.
Now that i'm down in the south, I had to hook up my A/C because its hot as ***** down here. Well the IACV controls the idle when its on, and my car was idling at like 300 causing havoc on the A/C. So I had to unblock the IACV so it wouldnt die with the A/C on. Well immediatly the idle surged. Especially when i'd first turn the car on in the morning. It would immediatly idle at like 2300rpm, then surge between 1500 and 2000 until I drove it around a little. Then it would calm down and do the 1000-1500 surge. I was throwing check codes for the IACV left and right....but I had A/C. Well one day when I was tooling around under the hood, I noticed that my idle screw was out quite a bit. (from when I had the IACV unhooked).
Just for ***** I closed the screw all the way, and then backed it out maybe half a turn. I reset my ecu to get rid of the light. Cranked the car up...NO SURGE AT ALL!!!
It appears that having my idle screw out so far was causing a vacumme leak. The screw wasnt out so far like it was going to fall out, but it was about flush with the face of the throttlebody. I'm now happy, with no surging idle, and my car idles rock solid with and without the A/C on.
So if you have a surging idle, I suggest you at least check the idle screw.
