Anyone heard of a "vacuum assist valve?"

[KTM300]

I am looking at buying a 95 Talon TSi AWD and the owner says it needs a "vacuum assist valve." I have never heard of one of these and did some searching and couldn't find anything about one. Anyone have an idea what he is talking about? He says the car bogs and hesitates anytime you punch the throttle below 3000 rpm. He says above 3000 that it runs fine. I live 2 hours away and won't have time to go look at it and drive it until this weekend. Thanks.

 

[Mr Peepers]

All I can think of is the guy knows carburetors and isn't use to turbo lag. An accelerator pump on a carb squirts fuel in when the throttle is pressed to keep the engine from leaning out and hesitating from the sudden increase in airflow. Although this is not operated by vacuum, I have heard it referred to as many things. Someone please correct me if I'm wrong, but the only vacuum assist on a DSM are the brakes. Edit: and BOV/CBV duh

Good luck, maybe when you test drive it it'll just be the boost threshold or turbo lag

 

[1g_tsi_awd]

Yea, vacuum assist valve? Don't think so... Boost leak maybe?

 

[spoonman]

I agree with mr. peepers, I have never heard of a vacuum assist valve. I checked my repair guide and could not find it there either. The man must have confused the name when he told you.

 

[KTM300]

He has owned the car for nine years and this problem just started happening supposedly, so I don't think it is just the turbo lag. He said he talked to the Chrysler dealer and they told it was the "vacuum assist valve" and that it would be $600 to replace. Does that price give you any better idea what it might be?

 

[Calan]

Could he mean PCV valve?

 

[1g_tsi_awd]

That is exactly what I was thinking.

 

[Cs4g63]

I sure hope its not the PCV valve that Chrysler wanted to charge $600 to replace for him. That would really suck if they were trying to take advantage of someone that badly.

 

[thekellbeast]

Vaccuum assisted brakes?

 

[Mr Peepers]

The only other thing I can think of is a leaking brake booster causing a vacuum leak.

 

[Defiant]

Muffler alignment bearing pillowblock dog winder cardigan.

Could be a leaking boost fluid manifold bypass reservoir floodgate, too.

 

[Mr Peepers]

Muffler alignment bearing pillowblock dog winder cardigan.

Could be a leaking boost fluid manifold bypass reservoir floodgate, too.

x2. Both of these are about $600 at the dealership.

 

[oldman]

Come on guys, I can't believe none of you know what a "vacuum assist valve" is!!!!!

 

[staticbrainwash]

A dealers way of calling a bov or WG something much more complicated?

 

[Cobrasatellite]

I agree with Static maybe dealers fancy way to say wastegate
My local Dodge dealer told me I couldnt put a Laser motor in my Eclipse becase
"Laser is a dodge/plymouth car and the eclipse is a mitsu"

 

[staticbrainwash]

And for 600 bucks, i can't think of anything else that would involve that much labor.

 

[Mr Peepers]

A BOV makes the most sense to me, just not the price. Have him point it out whenever you see it, and please tell what it was. The suspense is killing me.

 

[1g_tsi_awd]

A BOV makes the most sense to me, just not the price. Have him point it out whenever you see it, and please tell what it was. The suspense is killing me.

Me toooo. "And so it goes, the days of our lives..." (Soap opera narrator voice)

 

[bling5tatus]

Muffler alignment bearing pillowblock dog winder cardigan.

Could be a leaking boost fluid manifold bypass reservoir floodgate, too.

That's a bit excessive, I think it's just the muffler bearings going out causing the vacuum problem.

 

[KTM300]

Thanks for the replies and ideas. Hopefully whatever it is won't cost anywhere near $600 to fix. I will let you know once I check out the car and find out.

 

[KTM300]

I went ahead and bought the car last night, even though I am still not sure exactly what the problem is. You basically can't go over 1/2 throttle without it stumbling and missing so bad that it almost dies. I will get a boost leak test done tonight or tomorrow and report back.

 

[Skusssssh]

ok what i think this guy is talking about is the the intake and the exhaust valves are open at the same time. and what happens here is the the intake valve opens at the tail end of the exhaust valve and due to the heated gases trying to come out of the cylinder create a vacuum and this helps the intake pull in even more air than usual. this isnt a valve that you can go out and buy. it is done by the cam. and its all in how the lobes on it are placed and all. this is something that i actually heard about on "extreme 4x4" just this weekend.


also if it is what i think he is trying to say. $600 is about the right price for a set of cams that would cause this vacuum assist. -----think about it

 

[tkelly27]

, thank god for extreme 4x4! Actually that's called scavenging and it's not something that exists once the turbo is spooled up, and I'm not even sure ever at all with all the back pressure from the turbine.

I've never heard of anything like a vacuum assist valve. It's good that you bought it though. Do a boost leak test, check the check engine codes, look for any obvious sensors, spark plugs, or anything else unplugged, check the cam timing. You'll eventually track it down, and if you fix it yourself it won't cost you $600.

 

[Mr Peepers]

Although it is true, and is called scavenging, I don't think it's quite on track with the context of this thread. If the timing jumped it would affect the valve overlap, and if the cams were worn it would too, but I'm having a hard time with exhaust gases being evacuated from the cylinder and relating to his problem.

tkelly27 beat me to it, and is right about the turbo making a huge difference how valve overlap/ scavenging affects the engine once under boost.

 

[Skusssssh]

ok well i was taking a stab at it. im not too strong on the 4g63 but thanks to you all out there getting more info every day.