Last updated: January 26, 2002

AWS Modification

Date: Tue, 11 Jun 2002 00:43:22 -0400
From: Brian (
Subject: Re: (rx7) [3] Throttle Body Bypass

> When people bypass the throttle body water passage on a [3], do they
> just connect the rear housing nipple to the water pump nipple or is the
> preferred method to simply block both?  I'm thinking just block both.

The coolant is circulated through the throttle body to run the fast idle system. Basically when the coolant warms up, it heats a wax pellet on the side of the throttle body which expands and pushes a rod outwards that takes the car OFF the fast idle setting.

I don't care about my fast idle and would rather get rid of everything possible under the hood that I don't need. I'm content to put my foot on the gas a little to keep it from stalling if needed.


From: Ken Walanski (
Date: 1/19/00


The Accelerated Warmup System (AWS) slams a stone-cold 3rd Gen engine to 3,000 rpm immediately after startup to promote faster warmups for reduced air pollution emissions. This cannot be good for the engine. It is also very painful to those who care about their engines. Several approaches can be taken to disable the AWS.


Putting the car in 1st gear during startup will cause the ECU to disable the AWS. This is the easiest approach. The clutch must, of course, be engaged while cranking the engine. Don't accidentally disengage the clutch. The ASW will function when others start your car "normally".


Plugging the ASW tubing works well and is reasonably simple and costs very little. There are several approaches which people have taken, all of which are designed to cut off the flow of air.

The AWS is shown on page F-83 of the Shop Manual but unfortunately, it does not provide a clear picture of its location. It consists of 3/4-inch OD black rubber tubing which runs from a nipple on the curved crescent shaped aluminum intake pipe immediately upstream of the throttle body to a metal tube which connects to a solenoid valve under the extension manifold. This nipple faces the driver. After several inches, the AWS tubing connects to a metal tube which disappears down and under the throttle body. The connection to the solenoid valve which cannot be seen.

To stop the flow of air from moving through the AWS system, I made a metal plug by cutting a 1.25-inch long piece of 5/8-inch metal rod from Home Depot (and had 34.75 inches of rod left over). Make certain to file and scrupulously clean off any burrs so the engine will never suck in metal shavings. With a razor blade, cut the ASW tubing completely through about 2 or 3 inches from the nipple and insert the metal plug halfway into the cut tubing. Reconnect the other end of the cut tubing to the plug and wrap it with electrical tape. That's it. The AWS is then disabled.

Another way to prevent air from flowing through the AWS is to completely remove the rubber AWS tubing and insert a plug into the nipple and another plug into the metal tube. This may be more difficult because of access limitations. Again, the concept is to prevent air from flowing through the AWS.

Several people who have plugged the AWS tubing have subsequently experienced engine stalling on startup. Others have not. One fix is to drill a small hole through the metal plug to allow a small amount of air through the AWS. Again, be extremely careful to remove all metal shavings from any drilled openings since they are not good for the engine.


Yes, unplugging the ASW solenoid valve's electrical connector will disable the ASW system but will also cause the "Check Engine" light to come on. That's the reason no one does it this way.


Date: Mon, 26 Apr 1999 15:34:18 -0400
From: Max Cooper (

I recently installed a new intercooler and a GReddy intake elbow. The GReddy elbow does not have the large nipple on the outside of the elbow bend that is required to hook up the AWS (Accelerated Warm-up System) hose.

That leaves you with three options for the AWS: vent it to atmosphere, plug it up, or reconnect it to the intake plumbing. Here are my thoughts, opinions, and experiences with each of these options.


After consulting the list, I decided to vent it. Because intake air is drawn in to the engine through this hose, it clearly needs to be filtered. I bought a small K&N filter from Elite Motorsports ( for this purpose. It is a tight fit, but I installed the filter directly on the metal pipe that comes out of the manifold. This was a nice clean installation and I was initially very happy with it.

My first time using the car was a few short test runs on a Thursday night, and then Friday I drove down to Summit Point for MADS (a 500 mile trip). Everything was working fine. Then I was on the track on Sunday, and after the first session I found oil all over the middle of the firewall and the surrounding area. Yuk! It was coming from the AWS vent filter.

Why would the AWS solenoid be open on the track? I thought it was only supposed to open for cold starts? Well, I think that it opens due to only having the boost pressure on one side of it, where when it was plumbed to the intake before it has the same pressure on both sides. It's just a theory, but I think it is opening under boost.

I spoke to another vented AWS guy at MADS and he said that he gets some oil leakage that he just cleans up periodically, and that it was not a big deal. A contributing factor to the huge amount of oil that leaked on my car is that my first turbo is near death and must be dumping a lot of oil into the intake. Needless to say, I don't want this thing vented anymore.


The AWS is commonly described as being a system with the single purpose of warming up the pre-cat by making the idle quite high (3000 RPM or so when it is really cold). Running the engine at 3000 RPM right after it starts seems like a bad idea in terms of wear and longevity, and I don't have a pre-cat, so disabling this system seemed like a no-brainer.

Yesterday, I plugged the AWS. I removed the filter, and found that it was much easier to get off than it was to get on. I think that it had stretched to its new dimensions, but it was not damaged and was still suitable for the task. The worm gear hose clamp that I had installed had loosened quite a bit, also to my surprise.

I installed a heater hose plug (5/8" I think) that I bought at the auto parts store. It was one of those HELP! products that I have been growing surprisingly fond of (check valves, AST removal plugs, etc.). The cap fit reasonably snugly and I put a new hose clamp on it.

It is still on there and I haven't seen any more oil, so I am reasonably pleased with the result. However, the car stalled this morning right after I started it (which it has never done before, and it was not even cold out), so I am left to question whether the AWS may be present for more than just emissions purposes. Also, I read a post in the last day or two about what RPM the engine would idle at with the AWS plugged. The report included mention of the engine stalling after the first start.


So, now I want to replumb the AWS. A local friend of mine has an HKS piping kit (which is also missing the nipple for the AWS) and he had a shop add a nipple onto the pipe. I think it cost <$50, so it is not a very expensive modification.

It seems like this is the best solution. I don't want oil leaks or stalling, so this is the solution for me. If anything else happens that is weird, I'll report back (with info on how and why you should add a tiny AWS turbocharger ;-), otherwise you can assume I am happy with my replumbed AWS.


Date: Mon, 26 Apr 1999 22:45:35 EDT
From: Ken Walanski (

Yes, you very accurately described the AWS tubing and its location. So, it would appear that you have correctly located it. Interestingly, the tubing is actually 5/8-inch diameter except where it attaches to the nipple immediately before the throttle body where the tubing is 3/4-inch in diameter. That is, the tubing "flares" a little at the point where it attaches to the nipple. (I didn't measure the tubing diameter at the other end.) It is your choice as to which approach you use to disable the system.

There have been several posts by those who successfully plugged the ends. I plugged the middle of the tubing with a 5/8-inch diameter steel rod about one-inch long after cutting the ASW tubing in the middle with a razor blade.


Date: Thu, 25 Jan 2001 15:24:42 -0800
From: "Hoskinson, Jeff" (

The AWS (accelerated warm-up system) cranks up the idle on your dead cold FD to 3000 rpm unless you start it in gear or tap the gas.

If you want to eliminate the system and get rid of the solenoid I have designed and had CNC machined out of aluminum some block off plates that match the flanges on the stock parts.

AWS block off plates

To install them you need to remove the upper intake manifold (every FD owner should know how to do this anyway) flip it over and remove the 2 AWS components and the studs for the AWS solenoid and replace them with the plates and 2 bolts. It also makes it easier to remove/install the upper intake manifold in the future since the pesky AWS is gone.

If you run a Greddy elbow then you won't need to plug the nipple on the stock intake elbow (obviously), if you have the stock intake elbow then you'll need to plug the nipple in it


Jeff was selling a set of AWS block-off plates. He might still have some left. As his note mentions, you need two plates.

From: Hoskinson, Jeff []
Sent: Wednesday, January 10, 2001 11:29 AM

I have a few of sets of AWS block off plates for sale. 1 plate for the AWS solenoid and another for the hose. They are a perfect match for the flanges on the stock parts. Pic available.

$25 + shipping


Date: Wed, 13 Jun 2001 06:36:23 -0700 (PDT)
From: Chuck Westbrook (
Subject: Re: (rx7) (3) AWS disable ?

Remove the green pipe that goes from the solenoid to the intake elbow along with the hose. Place a blocking plate on the solenoid where the pipe was. Put a cap over the elbow pipe. This frees up some space.


Date: Wed, 14 Jun 2000 15:49:29 -0400
From: "Wade Lanham" (
Subject: Re: (rx7) Greddy Elbow Question

You can pick up a threaded nipple at your local auto parts store. It would only take 15 minutes to tap the back/lower part of the elbow, put some pipe dope or teflon on the threads, and put the AWS hose on it. I'm not sure why people don't do this (instead of venting it or capping it).

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