Is the air bypass solenoid valve absolutely necessary? The reason I ask is because while trying to put the intercooler back on and while connecting the hoses that go to the valve, I broke off the little plastic nipples on the bastard. It says in the FSM that it basically just helps the BAC valve, so it doesn't sound like I have to have it, but I just want to make sure. If I have to get another one this will keep me from getting my car running in the next couple of days (after sitting for around six months).

 

Nope, not necessary. It is what is responsible for the 3K startup. One of the few "extra" components to which I just say "Trash it!".

 

Sweet, thanks. To the trash it goes!!

 

aaron cake actually recommending the removal of something? This cant be happening!

 

would just unplugging the solonoid keep the car from reving to 3K on startup?

 

One quick other question. OK, there were 2 plastic nipples that were on the air bypass solenoid valve. The more vertical one went to the intercooler right, well where did the more horizontal one go to? It's been so long not having the intercooler and stuff on that I forgot where it went. This is for a 88 Turbo II. Thanks.

 

Like me, Aaron only recommends removing redundant stuff, as opposed to anything you don't like the look of or don't understand, like most peole here seem to do.

 

The other thick hose simply leads to a nipple on the intake (upper, behind the throttle body if I remember correctly).

 

where is that valve your talking about on an n/a?

 

I believe it's on the driver side of the dynamic chamber right below the BAC valve.

 

The lack of a Air Bypass Solenoid will keep you from getting the 3000rpm upon startup. Now that it's gone.....it'll only rev to about 2300 rpm. Heee heeee.

On a non-turbo series four its on the left side of the engine, mounted on the dynamic chamber about one inch fwd and inboard of the oil filter.

 

So will unplugging it be the best way to get rid of it or do I need to block off where the hoses connect to the BAC and the intercooler and remove the valve altogether?

 

I thought we discussed this already, Hailers...Even the old school gurus that have responded have it wrong...

If you remove the air bypass solenoid (and relay, for that matter), the 3K warmup still works. The majority of the time it's more like 2.8K, but she's still doing her warm-up thing...I removed mine (along with the relay) to inactivate that system, and to my surprise on the first start she actually went to 3K again. The BAC must be responsible for MOST of the 3K warmup's oomph...

 

That doesn't answer my Q though. Reason I ask is that I've diagnosed a good portion of the intake system to hunt down idle probs, including: vac hoses, bac, afm, tps, thermowax, etc and the only thing that didn't come out okay is the Air bypass solenoid valve.

So if I remove that, will it have any affect on my idle?

 

The ABV doesn't physically enter the TB itself, the hoses that attach to it do...Therefore the ABV cannot by itself cause a vac leak....

I used a couple of plastic plugs & some RTV to cap off the open ports after removing the ABV...

In regards to your post above, how can the TPS cause a vac leak? The threaded inserts on the TB casting don't enter the air chamber...

What I've noticed about vac leaks on our cars over the years is that it's usually not an obvious culprit (like a vac hose) causing the problems...It's usually in an area that two flat components are bolted/sandwiched together, like the UIM/LIM junction, or the ACV mounting pad, or (in my case) a block-off plate with the wrong thermal properties to match the base metal it's attached to...

 

i thought the valve that connected to the TMIC was for the power steering. whenever you turn the wheels, a relay on the PS pump kicks on which triggers a valve to divert more air into the motor to keep it from stalling out under the load at idle. maybe i'm thinking of a different valve.

 

You're right- power steering is one of the inputs to the ECU that makes it energize the relay, in turn energizing the solenoid valve...

 

Thanks for the input, Wayne I'll look into some of things you mentioned.

BTW, I didn't mention anything about the TPS causing a vac leak. I said that I was hunting down possible causes for my idle problems. I checked resistance on the items listed where resistance could be tested. And as I mentioned, the ABV is the only one that didn't give the proper resistance.

Again, thanks. I'll get rid of the ABV.

 

Sorry to disappoint.....but on a turbo, series four, the air bypass valve does not respond to power steering input. It's the Air Supply Valve, located on the back of the throttle body. Out of sight...out of mind. Located just to the left of the series four turbo's EGR valve. It's in the FSM, that is free, online, pictoral in nature, and a really fine read. Never leave the house without one. I'll download it and print it for cash. Say 90 bucks?

 

You're thinking of the Turbo-only ASV on the back of the UIM. You are correct about it's operation, but NA's do it differently.

 

lol...I already have a hardcopy specific to the S4.

 

ditto, i've had mine for a few years now. i got it from mazdatrix not too long after i got my car

 

dude.. my little thing broke off too, so i just connected the hoses to close off the vaccume. My **** used to stall all the time, but now it's cool. Oh.. the only thing now.. is that it idles at 2k, but you can adjust your idle

 

dude.. my little thing broke off too, so i just connected the hoses to close off the vaccume. My **** used to stall all the time, but now it's cool. Oh.. the only thing now.. is that it idles at 2k, but you can adjust your idle

 

So if I remove this do I just cap the nipples where the hose was?