Idle when A/C is on

[elerner]

What is supposed to compensate the idle when the A/C is on? It's been really hot here (c'mon 90's is pretty hot for us! :D ) and I've been turning off the compressor whenever I come to a stop to avoid from stalling.

[Tom @ Fast Forward]

You need to do the Idle Adjust procedure. The IAC valve controls that. The ECU 'learns' the different load conditions and adjusts. evidently you hadn't run the AC much when you did it the first time. SImply drive the car and let the engine warm up (shouldn't take too long in that heat) and then with it idling, pull the plug on the IAC valve and adjust the idle stop screw for no change in idle. If it is running correctly, at idle the RPM should step up 200-300 RPM when you turn on the AC and back down again when you turn it off. After a couple days this may need to be done again.

[Kyp J]

Re. the IAC, which end of the IAC should be connected to the "outside" of the TB? Fat end or skinny end? I have looked at the routing diagram and the hoses before, but there have been comments thath one or more diagrams may be wrong. I am thinking I might have it backwards. I have packed up my books and the car is getting ready to be loaded in the trailer. Ever since I put mine back together it has been goofy in the idle function.

[Tom @ Fast Forward]

I don't think it makes an awful difference but the end away from the connector is what I use.

FWIW, I found that moving the little plastic restrictor to the end of the hose that connects to the drivers side of the valve cover makes the idle even better.

[Kyp J]

I don't think it makes an awful difference but the end away from the connector is what I use.

FWIW, I found that moving the little plastic restrictor to the end of the hose that connects to the drivers side of the valve cover makes the idle even better.

Doesn't the ECU try to increase idle by moving the internal air passage control a specific direction? If backwards it would seem to slow instead of increase idle air which is kind of like what mine does....maybe. I wish I had time to swap it to see what happens, but I don't. I'm even shutting down my router and DSL box to pack them real soon now.

[Tom @ Fast Forward]

It is just a valve opening to allow more flow and closing to allow less. It has a spring and the original mount on the car had in to the hole away from the connector so that is what I show. I don't think it makes a difference. Just doing that creates uniformity among kits.

I used to recommend putting the restrictor in the line from the IAC but we found it to work cleaner with it in the line to the drivers sdie valve cover. It was originally used to reduce flow through the valve cover and does a good job of it in conjunction with the PCV valve.

[Kyp J]

OK, I get it now. For some reason I was imagining something more exotic. Like a diode I guess. Air doesn't have polarity?

[elerner]

I don't think it makes an awful difference but the end away from the connector is what I use.

FWIW, I found that moving the little plastic restrictor to the end of the hose that connects to the drivers side of the valve cover makes the idle even better.

Hmmm, any idea why the location of the restrictor in that hose would make a difference. I've got it right by the IAC (pushed it into the hose using the IAC barb).

[Tom @ Fast Forward]

By the IAC, it restricts the IAC. By the valve cover it restricts the air that bypasses the IAC. Gives the IAC more control.

[elerner]

Relocated the restrictor by the valve cover and all is hunkey dorey now. I actually had it installed in the hose from the IAC to the VDB. Not sure why.

Tom, I took a look in the current 01-05 instructions and there is no mention of that little restrictor at all. Thought I'd mention it.

[Tom @ Fast Forward]

I have to make a couple final instruction manual changes for CARB this week and will insert it then. Thanks for the reminder.

BTW, anybody else with the restrictor in the IAC circuit, you might want to do the same thing. Just pop it out of the hose and re-install it in the end of the hose that goes to the drivers side of the cam cover (valve cover). Put it right in the end of the hose at the cover. You might have an idle issue after a day or two of driving an need a minor touch up to the idle. But try to avoid making an adjustment for a couple days if you can. Makes life a lot better if the ECU gets a chance to re-learn the new change. Make sure the ECU gets some stop and go driving with the A/C on and off during the 48 hours so the ECU gets to learn the load changes for A/C and no A/C.

Turn the A/C off for this procedure.

1. Disconnect the IAC electrical connector.
2. Adjust the idle for no change in idle.
3. Reconnect the IAC electrical connector and let it idle for a minute or so.
4. Go to step 1 and repeat until the connector can be disconnected and re-connected with no change in idle.

[ThomS]

Tom is this restrictor that you are talking about, is it one of the Check valves that we talked about in the past ? I don't have my car handy right now to look at . any pic's avaialble?

[Tom @ Fast Forward]

It is a small white plastic piece 3/8" in diameter and about 3/4" long with a 1/8" (more or less ) hole through it. It is used to restrict the flow. When you installed the kit, you probably put it in the hose to the IAC. Otherwise it is a left over part. It'would only effect idle. Some cars idle great even without it but most cars it helps eliminate idle droop and other idle problems.

[sinuous]

my IAC buzzed like crazy without the restrictor. I think it was limiting
out. or something like that. mine is in the IAC hose to TB or TBA I forget
wich one.
Seems to be fine, but I haven't run the air. should I still pull it out and put in on the driver side cam cover. And I'm a little confused by "in conjuctiion with the pcv valve"? my pcv valve and hose are on the passenger side of cam cover?

Jared.

[Tom @ Fast Forward]

Yep. Best to move it. All model years. What happens is that Air comes in through the air filter and MAF and up to the BTB. Then out through the BTB distribution block to the drivers side of the valve cover. Then the air sweeps through the valve cover and out the PCV valve into the TBA. The IAC makes up the difference in idle air as it is in parallel (so to speak) with the vavle cover air flow. As you have it now, it allows full flow from the valve cover and restricted flow from the IAC. When you make the change, it restricts the valve cover flow and allows the IAC to have full control.

[elerner]

Moving the restrictor seems to have also cured my "low idle on cold start" problem. Before it would lumber along and then slowly build up to it's normal idle point.

[Tom @ Fast Forward]

In my best Hannibal (A-Team) voice "I love it when a plan comes together". :)

[elerner]

Oh well, the initial lumbering idle on cold start seems to be back. It coincided with a drop in temperatures we've seen this past week (not sure if that has anything to do with it). This morning I threw a VTCS CEL that I bet was caused by the lumbering. Do other people experience this same low idle that builds after about 10 seconds on cold startup?

[Banshee]

Do you have anything hooked up to the o2 wire?

I found that when I hooked up the a/f gauge, it would cause what you're describing.

[Tom @ Fast Forward]

Especially with the 01-05 you will have poor idle for the first 10-20 seconds with a cold morning start. The ECU goes open loop and uses look up tables until the O2 warms up. Then it goes into control. The extra load of the SC makes the idle low/lumber until the ECU can see the O2. Good news is that it only lasts 10-20 seconds.