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[solved] Help! What vacuum hose is supposed to connect here? (photos inside)...

77K views 34 replies 18 participants last post by  rbarrios 
#1 ·
First, the short and to the point version:
I have a vacuum leak and found this hose connection point behind the manifold on the passenger side of the engine with nothing connected to it (see pics). There isn't an obvious line anywhere I can see. Can someone point out what this should be connected to?

All the details:
2008 Acadia SLT2 with 90,100 miles on it. Two weeks ago while sitting at a stoplight, my check engine light went on, as well as the *ding ding ding*'service stabilitrac/traction control off' messages and light on the display. Odd thing was that the stabilitrac error would disappear as soon as I accellerated away and then come back on when I let off the gas for a few seconds. Wherever I went, the stabilitrac would be fine while speeding up and then disingage again whenever I was slowing down or stopped. I have a code reader and found codes P0171 'system too lean (bank 1)' and P0174 'system too lean (bank 2)'. When I cleared the codes, the stabilitrac error would also disappear. The engine would also idle rough, but seem to run fine once the vehicle was moving.

After doing some research online, I changed the MAF sensor (the most common cause for those error codes). I also replaced the air filter, cleaned out the throttle body, and inspected the rubber air intake sections for cracks while I had things apart. Everything appeared to be in good shape. Unfortunately, there was no change in the engine performance or error codes.

Frustrated, I researched some more and determined I likely had a vacuum leak somewhere in the intake manifold. I did another inspection of all of the visible lines, rubber parts, and plastic parts. Everything was tight and in good shape. Finally, while running the engine, the cooling fan kidked off and I heard a slight sucking/hissing sound from the opposite (passenger) side of of the manifold. After spotting a small protrusion on the back side, I slid my hand behind and placed my finger over the end. I felt it pull suction and immediately the engine idle smoothed out and purred along like normal. Eureka - I found my leak!

Unfortunately, I can't seem to find a loose hose end anywhere to plug back in to the connector...at least not from the top of the engine compartment. I'm hoping that someone here can point me in the right direction as to where this spot connects up. In the meantime, I have placed a temporary cap over the stub to stop the air leakage. After a short drive this afternoon, no errors, lights, or codes.

Thanks in advance for your help!

edit: OK, so my attachments aren't visible and it won't let me post any direct links. If you remove the spaces from the following link and paste it into your address bar, it will take you to the photos until I can figure out what else to do.

http ://web. alliancecom.net/boerhave/vacuum2s.JPG
http ://web. alliancecom.net/boerhave/vacuum3s.JPG
 
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#2 ·
Re: Help! What vacuum hose is supposed to connect here? (photos inside)...

Well, that sucks!! :eek: :eek: (Too bad we can't see the pics.)
 
#4 ·
Re: Help! What vacuum hose is supposed to connect here? (photos inside)...

the pics work as long as one removes the extra spaces in the page links. :thumb:

I'd go out to look at my setup, but can't help right now as it's late and HiYo is asleep! ;D
 
#6 ·
Re: Help! What vacuum hose is supposed to connect here? (photos inside)...

Did you ever figure out what hose is missing? If not maybe I could look for you after work.
 
#9 ·
Re: Help! What vacuum hose is supposed to connect here? (photos inside)...

OK, mystery solved...there's only supposed to be a rubber cap over this port :thumb:. I coaxed one of my neighbors down the street to lift the hood on his Acadia and we took a look. I wonder why the port is there?

...and I promise to rinse out my engine compartment this weekend, I admit it's a bit dusty. :-\
 
#10 ·
diagnostic port?
 
#11 ·
That's a good guess. Could be a port for some accessory on another vehicle that uses the same engine.
 
#13 ·
Might be for the engine-bay vacuum cleaner!
 
#14 ·
Hello. I too had a problem with hard starting and rough idle. saw the same port exposed and covered it with a pencil eraser till i got to the parts store. disconnected batt to clear codes and engine ran fine with no check engine light. After 40-50 miles, engine light came back on, screen said service stabilitrak and traction control. Went to autozone to get a check engine scan, and scanner picked up codes P0172 and P0175. I wonder if the excess air the motor was getting(lean mixture), damaged other parts before i figured out the problem? vehicle has 97,000 miles so far.
 
#15 ·
dugan562 said:
Hello. I too had a problem with hard starting and rough idle. saw the same port exposed and covered it with a pencil eraser till i got to the parts store. disconnected batt to clear codes and engine ran fine with no check engine light. After 40-50 miles, engine light came back on, screen said service stabilitrak and traction control. Went to autozone to get a check engine scan, and scanner picked up codes P0172 and P0175. I wonder if the excess air the motor was getting(lean mixture), damaged other parts before i figured out the problem? vehicle has 97,000 miles so far.
Do you plan on taking the vehicle to the dealership about the codes that were pulled?

Michelle, GMC Customer Service
 
#16 ·
We are planning on going to dealer this weekend, only to trade it in. We had so many problems with this car this year, tires needing rebalancing every month, a/c pressure hose going out, rear a/c not working correctly, rough idleing from time to time, engine hard starting every time we fuel up. Car lunging forward at a stop light like we got pushed, remote start not working anymore, "service stabilitrak" "service traction control" comes on from time to time. Dealer cant find the stored codes. Car has 97,277 miles so outa warranty, wonder if itll make a 100,000!
We have 6 children combined, youngest being 4 months. Dont want to break down especially when its currently 108 degrees here in az. Own the vehicle outright, so hopefully we dont have to put a down payment. Sigh....
 
#17 ·
dugan562 said:
We are planning on going to dealer this weekend, only to trade it in. We had so many problems with this car this year, tires needing rebalancing every month, a/c pressure hose going out, rear a/c not working correctly, rough idleing from time to time, engine hard starting every time we fuel up. Car lunging forward at a stop light like we got pushed, remote start not working anymore, "service stabilitrak" "service traction control" comes on from time to time. Dealer cant find the stored codes. Car has 97,277 miles so outa warranty, wonder if itll make a 100,000!
We have 6 children combined, youngest being 4 months. Dont want to break down especially when its currently 108 degrees here in az. Own the vehicle outright, so hopefully we dont have to put a down payment. Sigh....
I completely understand about your situation. I hope we will have the opportunity to regain your business in the future.

Do you have any ideas as to what type of vehicle you are going to want to trade the Acadia in for? This is not a marketing question; I am just curious.

I hope you have a great weekend.

Michelle, GMC Customer Service
 
#18 ·
THANKS FOR POSTING THIS ISSUE!

I've been chasing this for a few weeks now, replaced the MAF, was about to go for the MAP, but found this thread today... we replaced the spark plugs a and must have accidentally knocked this plug off. Anyway, just wanted to say thanks to the OP for putting this up here....
 
#22 ·
Thanks to all for this thread. I changed the spark plugs on my 2007 Acadia SLT and immediately had CEL, P0171, P0174, Stabilitrak/Traction Control, flutter, hard down shifts, etc. Checked for vacuum leaks on front and top of intake manifold and didn't hear or see anything. Found this thread and looked at the rear passenger side of intake manifold. There's a chrome tube/fitting sticking straight out of the intake manifold toward the rear, horizontally. No rubber cap on it any more. I'm sure I knocked it off when I was reaching back there to change the rear plugs. Installed a rubber cap and it's fixed. BTW, will need to disconnect battery to clear CEL, which is still on. Thanks again!
 
#23 ·
I would also like to extend my thanks. I changed my plugs (without removing the intake) and afterwards has the stabilitrak issues, CEL with multiple misfires and rough idle. I also had a weird clicking type noise which almost sounded like it was coming from the tranny. I actually noticed this when it came off, but I thought it was a cover protecting threads or somehow supported the plastic engine cover. Since the metal vacuum tube faces aft and does not have a barb or other vacuum type design to it, you don't think about it. Mine was cracked, so I electrical taped it and put it all back together and was good to go. What's sad is that in researching this problem several people have spent money, time and heartache at the GM dealer and they couldn't figure it out. And the noise I heard is often billed as injectors under high fuel pressure. So much for Mr. Goodwrench. I took some pictures, so maybe this will help someone better understand what is going on.
 
#25 ·
bmlock said:
Doesn't look like the photo attach feature is working right. I tried using Dragon (Chrome) and the links don't even show up. Sorry.
You are correct! Attachments don't work (haven't worked for some time). And, you're such a noob that the forum won't yet allow you to link anything. Try that after your 5th post.
 
#26 ·
Speleos said:
That's a good guess. Could be a port for some accessory on another vehicle that uses the same engine.
Yup!!! Nailed it right on the head...
Old thread.. but I figured Id update it--- since im sure it will be researched by someone asking why this thing is capped off...

But yes-- this connection is for vacuum--- to what the 2008 Enclave has...
A transmission mount- that is vacuum assisted.
The Tranny mount even has a nipple on it......

see this thread on the Enclave forum...

http://www.enclaveforum.net/index.php?topic=35842.0
 
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