slorimer

I know this has been asked before, cause I found it through the search, but no one ever figured out if its okay or not. Once warmed up and idling, should pulling the relief solenoid valve connector off cause a change in the idle on a S5 NA? Or this question also applies to an S4 NA maybe even turbo. Anyone? Some have suggested that this means your AAV diaphragm is shot, but others have replaced the entire ACV and it still did it.

HAILERS

With a perfectly good ACV, no, there should be no change in idle.

But if the anti afterburn diaphram or its poppet is corrupt, then there is a possibility of the airpump air actually going into the INTAKE runners.

As you know, when you let off the throttle at speed, the anti after burn diaphram sucks in and lets a small amount of air into the intake runners to prevent BACKFIRE.

After fifteen years or so that part of the ACV does not seal as good as when new. So when the Relief solenoid is engergized the airpump air is not dumped overboard and now goes to the exaust ports. When this happens there is more pressure inside the ACV and some of that air is now seeping thru the anti afterburn valve and into the intake tract. That messes with your idle.

And no, this blocking off of those two holes will NOT effect emissions in any way.

If you pull the plug off the Relief solenoid, then the airpump air is now dumped out that large hose on the bottom of the ACV to the right fender and theres less pressure in the ACV to seep thru into the intake tract.

So you can see why the idle speed changes if the Relief solenoid plug is pulled off.

No need to remove and tosss the ACV or even buy a new one. Just remove the ACV and with RTV, plug the TWO holes that effect the anti afterburn valve. This will result in the ACV having NO effect on idle no matter whan plugs you pull off.

One of the holes in the ACV dedicated to the anti afterburn valve is a vacuum hole to the runner. IT is what causes the anti afterburn diaphram to pull in. The other hole dedicated to the anti afterburn valve is the one that actually ports air pump air to the intake runner.

If it comes to it, I can post a jpg of the two holes that would be blocked off. IT's only a half hour to one hour job. Just three nuts to remove a ACV and a couple of vacuum lines/hose.

Turbo or non turbo?

slorimer

Hailers

I completely agree with what your saying, however, I read a couple of posts from joel91 and a few other members, whereby they rtv'ed the AAV holes and they still got the same results. Then they even went as far as replacing the entire ACV and still had the problem. That is why I think there may be another issue and was wondering if they ever solved the problem.

Mine is a 89 NT, which has this problem, along with a hunting idle. As well, as one of the members which had this problem mentioned, it idles better with the relief solenoid connector plugged in.

Any comments?

HAILERS

Well. The ACV is almost totally dedicated to feeding air to the exaust ports and the split air pipe.

The only part of the ACV that can make air go into the INTAKE runners and therefore change the idle mixute........is/are the two holes in the ACV dedicated to Anti Afterburn. The other holes in the ACV can't effect the idle/air mixure in any way.

The only other explanation, to me, is if the ACV gasket is leaking air from one port to the other in the ACV. You can make a ACV gasket out of gasket paper in a half hour or so to replace the one you have if it's suspect.

I can't account for other folk still having a problem when the Relief solenoid is disconnected, UNLESS they plugged the wrong two holes on the back of the ACV.

I mean, those are the ONLY two holes that go to the INTAKE at all. Small ones at that. Can't happen if they're shut off/plugged off.

HAILERS

Then maybe it's not the ACV but sometning to do with the Relief solenoid itself or the routing of the hose to and from the Relief solenoid.

If at idle with a fully warmed up engine, if you pull the vacuum line off the nipple from the solenoid to the acv, at the acv end, you should feel a vacuum on the vacuum line. Pull the blue relief solenoids elec plug off and the vacuum should stop.

That should show the vacuum is going where it should. Then take a piece of vacuum line and put it on the metal nipple that *feeds* the ACV, and suck on it. It should hold a vacuum, proving the diaphram inside isn't leaking air to the wrong places.

I mean it could be a misrouting of the vac lines on the solenoid? Line not going where it should? Or the solenoid is passing air/vacuum to the solenoid FILTER instead of to the acv' feed nipple? The filter on the solenoids pull off and can be installed on either of the other nipples on that solenoid. Look at the Relief solenoid and the Switching solenoid and notice how their FILTERS are on different nipples on the solenoids.

Maybe someone else has an idea. I have no more.