joel91

ok if i disconnect the blue solenoid connector at idle why does my idle drop 200 rpm????

HAILERS

The anti-afterburn valve in the ACV is busted/leaking air from the airpump into the intake. When you disconnect the Relief solenoids plug you dump the airpump air overboard and in turn away from the leaking area. Make sense?

joel91

yea...but could the blue solenoid if it was faulty somehow could it cause this too???

HAILERS

The BLUE solenoid is responsible for supplying the ACV with vacuum to the Relief diaphram in the ACV.

The solenoids are almost bullet proof. At idle it is energized. It has 12v on it any time the key is to ON. It has a ground on it when the TPS is set right and the engine is at idle. The ECU puts that ground on it IF the TPS is set right.

If you pull the plug off the Relief Solenoid it STOPS supplying the acv with vacuum to the relief diaphram in the acv. The airpump air then dumps overboard.

All you have to do to prove the solenoid is good/bad is to idle the car. When fully warm/hot, pull the two vacuum lines off that are just above the acv. Both should have vacuum on them. One is from the Relief solenoid and the other from the Switching solenoid.

The Relief solenoid is just a gate for vacuum to the acv's relief diaphram. Energized you have a path of vacuum to the ACV. De-energized cuts the path of vacuum.

The only reasonable cause for the idle to drop 200 rpm when the BLUE plug is pulled is............the ACV's anti-afterburn diaphram is busted and leaking air into the intake. It's putting that air into the intake under the pressue of the air pump. If you disable the Relief solenoid to dump that pressurized air in the acv overboard so now the leaking diaphram isn't letting air into the intake as much as before.

I'm sure there are other opinions out there.

To determine which is which, pull the plug (Blue) off the Relief solenoid. One of the two vacuum lines above the acv should now lose its vacuum. That one will be the one from the Relief solenoid.

joel91

your right just pulled the solenoid it checks out per fsm....

joel91

i don't know if you remember but i already rtv'ed the anti afterburn holes in the acv i have the acv sitting right in front of me right now...is there any possible way that something else in the acv could cause this. what are the other diaphrams in there???

HAILERS

I remember.

I was thinking if someone got the vacuum lines arranged wrong MAYBE you would get your symptoms.

Like installing the three vacuum lines on the front of the throttle body wrong. Yours is a non turbo I think.

Of those three metal nipples on the front only one is pulling a vacuum. The other two are for the oil injector spider and the fuel injector air bleed. Mixing the fuel injector air bleed with the only one the has vacuum will give you a strange idle. The oil injector spider one is to big to get wrong.

I assume a series five na and series four na have the same three metal nipple arrangement. Guessing.

joel91

what effect would rtving the ports in the acv so that the relief solenoid wouldn't be able to work.....until i get another acv. would that hurt anything???

i have stock cats....

thanks hailers for all your help!!

joel91

are you talking about the vacuum nipples on the upper intake just above the acv where the upper and lower intake mate??

HAILERS

No. On a series four, on the front of the throttle body there are three metal nipples arranged one above the other. It might be different on a series five.

I wouldn't RTV anything other than that anti afterburn valve hole/holes. The other holes are needed by the catalytic converter.

I still don't understand how airpump air is getting by the blocked off holes and into the intake path.

joel91

yea i don't understand either how air is getting by but i can still spray starter fluid in the acv inlet and lower the rpm a few hundred. i may just try and find another acv. On a series 5 there is three nipples on the back of the throttle body near the firewall if that is what you are talking about they look like they go into throttle body spacer somehow. I looked at those vacuum lines and they look to right according to the vacuum schematic in the fsm. yea this is definately a stumper!! lol...if you can think of anything else let me know. thanks.

joel91

does anyone know where i can buy a new s5 acv at besides mazda they want like 350$...
aftermarket one maybe??

joel91

alright here's what i did today i decided to replace the acv gasket first before spending 400 bucks on a new acv...the old acv gasket was very brittle and broke into a small little pieces. Put the new gasket on and put everything back together. I was out of starter fluid, so i used carburetor cleaner(still flamable) to spray into the air pump inlet, NO change in idle!!Hmmm so maybe the gasket was bad???

So i went over to the relief solenoid and pulled the connector at idle. The idle still drops a hundred, but the engine is alot smoother at idle now than before. Hailers do you think thats normal??? I mean when you pull the relief solenoid at idle it cuts air to the exhaust ports right??

The other thing i thought about is what if the relief solenoids vacuum lines are mixed up like you said earlier. I looked at the fsm for a 91' and the vacuum diagram they give you can't see exactly to which nipple they go to for the relief solenoid. Does anyone have a good vacuum picture for an S5 that i could look at??

HAILERS

If you pull the Blue connector, the vacuum to the Relief diaphram in the ACV is cut off and now the air from the airpump gets dumped out the large black hose at the bottom of the acv and no air goes to the exaust ports.

I don't have a series five diagram for vac hose nor a series five to look at.

I HAVE noticed on a SERIES FOUR that if you get the hoses connected at the front of the throttle body (dynamic chamber actually, where the tb mates to the dynamic chamber) then the car will idle rought.

On a SERIES FOUR that's because you will have mixed the nipple that feeds air to the fuel injector bleeds and the line the goes to the vacuum spider.

I shoulda asked you about the condition of the gasket on the acv earlier and that would have saved you some time.

Carb cleaner works ALMOST as good as starter fluid.

I'll look around for a series five non turbo diagram later.

HAILERS

I took a moment to look at the online series five fsm and your vacuum lines are a bit different than series four.

I can't figure out whether the Relief and Switching solenoids get fed vacuum from one of the three lines on the back or one of the two on the side where the upper and lower manifolds mate.

IF it were me, I'd carefully remover the two vac lines off the RELIEF solenoid. ONE of them SHOULD have vacuum going to it at idle. The other should go over to the acv side of the engine.

joel91

right....the one on top of the blue solenoid is the vacuum line that goes over to the acv....i traced that line over there with a friend applying air into the end at the solenoid.

I had the acv off at the time and i know which hole in the intake it comes out of. I haven't yet traced the other vacuum line yet...it looks as if it goes into the rats nest somewhere



yea the fsm diagram isn't that great....

HAILERS

The one that goes to the vacuum piping SHOULD have vacuum on it any time the engine is running. It and one going to the Switching solenoid should tie together somewhere in the vacuum piping and lead to one of the three metal nipples on the back of the intake.

joel91

right the other one does go down to the switching solenoid....man its hard to trace that line from there...im goin to see if it has vacuum on it at idle be back in a few.

joel91

ok here it is... at idle the bottom hose on the relief solenoid has vacuum.connector hooked up, if you pull the upper hose off(thats the one that goes to the acv) there is no vacuum in that hose.

But with the car idling and blue connector hooked up vacuum flows from the bottom hose through the solenoid to the upper hose. But if you pull the connector off the bottom hose no more vacuum to upper hose...(guess it just pulls from little air filter on the solenoid right??)

joel91

i got a really good S5 vacuum diagram from Hughes....All acv vacuum lines are hooked up right. But what i did take notice is that on the bottom vacuum line to the relief solenoid there is a small check valve before that vacuum line gets to the solenoid... what i did was hook my vacuum gauge in opposite direction of the little arrow on the check valve, the check valve doesn't hold vacuum.....Could this be my problem Hailers????

joel91

what doesn't make sense to me though is if only the bottom vacuum line has vacuum on it and when you unhook the relief solenoid the solenoid switches the bottom vacuum line to suck outside air isn't that just like a vacuum leak????

HAILERS

How's this for an answer: The Relief solenoid only does what you describe when your over 3800 rpm. Your not likely to notice that small insignificant *leak* then. So I don't get pounded on.......in GENERAL the Relief solenoid only loses the ground at 3800. There are other conditions when it does that.

In other words it's ABNORMAL for the Relief solenoid to lose the ground on it at idle or for the plug to fall off.

joel91

hmmmm......so i am creating a vacuum leak then by unplugging the solenoid at idle then right??? So i've been checking this wrong the whole time???

joel91

but what doesn't make sense is if i am creating a vacuum leak at idle by unplugging the solenoid the rpms should go up, not down like it does. i checked all the vacuum lines again and they're all right from this S5 diagram. What are the chances that the acv could be bad?? just kinda running out of options.....

joel91

I went out today and bought another can of starter fluid, guess what the engine still about stalls when you spray it into the inlet of the acv. Im about to loose it ,i checked all the junkyards in my area....cannot find a S5 acv anywhere...hailers i know this has been a long sought out problem, but i need more help please. Before i go and buy a new one is there anyway i could shoot air down into the intake side of the acv and find out exactly where it is entering the engine at??

I've double and triple checked the vacuum schematic...all the vacuum lines are right. I even used my hand held vacuum pump to isolate each vacuum line to see where it goes. All are right according to that schematic i just posted. Any last help is appreciated.

micah