FAQ: What is the Black Box? (Series I SC)

What is the little black box in the back of the engine on top of the motor? It has a vaccum hose going to it...


Thanx all, Lance

I have no idea what youre talking about. lol


Is the car a 95 , or 96-99? supercharged or not? This info should be in your signature ideally. it helps a lot when asking a technical question ,as there are many variations of engine bay setups in our rivs.

That and posting a picture could help you get an answer much more quickly.

Sorry its a 95sc and its right on top of the motor connected on the back of the firewall in the center....


Thanx, Lance

sounds like the MAP sensor.

It's this thing, on the left of this picture. AA doesn't know what it is either. It's only in the '95s with the Series I motor. I have no idea what the hell it is either.

i think its a -non servicable - cabin filter.

I dunno eather but why only 1 vaccum hose going to it and I also dont think it goes into the cabin at all..And thanx for that great pic Ilan.....Hmmmmm, anyone else maby no what it could be? Thanks again guys or ladies,

Lance

I noticed that exact part yesterday and wondered what it was.

We're being tracked by buick through it.

... Actually, I just looked it up on Mitchell Repairmate, and I've found it to be simply a vacuum tank.

Ok, makes sense since there's a hose leading to it from underneath.

Sure looks like it would make changing the rear plugs a RPITA.

AA wrote:

Sure looks like it would make changing the rear plugs a RPITA.

Why yes, yes it does.

jamie wrote:

I noticed that exact part yesterday and wondered what it was.

We're being tracked by buick through it.

... Actually, I just looked it up on Mitchell Repairmate, and I've found it to be simply a vacuum tank.

PN...25603900

AA wrote:

Sure looks like it would make changing the rear plugs a RPITA.

You are correct!
We talked about this vacuum tank and changing the plugs on the ‘95s from underneath on another thread ... sometime, somewhere?

Thanks all, thats what i kinda thought..Is there a purpose for it?And I just did my plugs from underneath, it was easy....

It's a vacuum reservoir. I think it is used to make sure that you have enough vacuum to run the brakes.

looks like a cabin air filter to me i dont have it on my 97

No cabin air filters on the 95-99 Rivs.

[quote="IBx1"]It's this thing, on the left of this picture. AA doesn't know what it is either. It's only in the '95s with the Series I motor. I have no idea what the hell it is either.

I have a 95 with a Series II N/A and the same vacuum reservoir.

OK I finally found out this mystrey!!! It is a vacume tank for the cruise control!!!!!! Aperently it holds extra vacume for it... And it was for the 95sc.. O and also it was discontinued on 11/05.........


Lance

I was told once that SC cars don't have as much vacuum as N/A cars. I was also told that one key 'feature' of the Riv (and other luxury cars) is they're designed to hold speed on cruise control on interstate highways going uphill (I forget what the max interstate grade is, maybe 10%?).

Anyway, there are various ways to ensure that. One is to use a vacuum tank to help the vac-operated cruise hold speed up grades (when engine vacuum dips). Another - used on the later Rivs - is to use an electronic cruise control with an electric servo instead of a vac tank.

To find that servo just trace back the throttle cable that's not terminated at the accerator pedal.

Albertj

I think they stopped using vac-operated cruise in the early 90s somewhere. I know my '94 Regal had a servo-based cruise.

Extra vacuum for the brake booster?

My 95 SC has it....

but my cruise control doesnt work....

vendetta wrote:

My 95 SC has it....

but my cruise control doesnt work....

I had problems with my '95 cruise, unplugging and cleaning the connector under the hood fixed mine, might give it a try, you never know?!?

I have it on mine and I was told it is a vaccum tank, there also was one on my 1995 Series II as well

hello group, just looking under the hood of the old beast and saw a vacuum line not attached, finally saw that it went to the rectangular box bolted to the firewall - center top, is that a vacuum holding unit like the old ball i used to see? Thanks
Jeff

Welcome to the board, Jeff.

Please fill go into your Profile, Signature, and fill out some information about "the old beast", so we have some idea of what you are asking questions about... '95s for example have a LOT of things different from the '96-99s.