LT-1 Intake Manifold / Port Identification

[SSTibet]

Folks,

I have attached a picture of driver side (rear) of the intake manifold. Looking at my engine, I see one of the AIR system tubes being branched into the port I have shown in the picture (with a question mark).

But since the AIR system works around the exhaust manifold I do not understand why it is connected to the intake manifold.

I need some education here

Cheers

 

[SSTibet]

So no one knows what that port is???

 

[Hrtbeat1]

I'm pretty sure its the EGR feed. There should be a tube that connects there that goes to the exhaust manifold.

 

[SSTibet]

So there should be a tube attached to this port and feeding into the EGR valve, right? Makes sense to me. But I remember seeing a tube branched from the right side (engine) of the AIR supply going into this port. I will check on the engine.

Thx

 

[Hrtbeat1]

I don't have a LT1 but they shouldn't be much different. One port is the EGR feed and the other is the EGR valve itself. The feed should be just a pipe going from the intake to the exhaust manifold. The valve gets its input from inside the intake manifold.

 

[SSTibet]

I though the two holes in the EGR flange, where it mounts to the intake manifold, provides the exhaust feed & return. And therefore there should be no other pipes running into the EGR other than the vacuum line.

Cheers

 

[redc4corvette]

I think it's the riggen sack ? or is it the holden brack?

Well I know that it goes to your electric air injection pump one line goes to the right manifold injection tube top and the other to the left top of the exaust manifold injection tube,it tee's off of the tube that screws into the manifold. :duh

 

[SSTibet]

So the air from the secondary air injection system (AIR) is somehow routed through the intake manifold??? Something like this: AIR pump - Intake manifold in - Intake manifold out - branch 1 goes to left exhaust manifold, branch 2 goes out to right exhaust manifold ???

Cheers

 

[redc4corvette]

The part that comes out of the intake is metal with 2 bolts and at the top of the metal pipe it is a y.
On both sides of the y are rubber hoses that lead to pass side top injection hose and the other hose goes to the drivers side top injection tube but before it goes to the drivers side top hose it y's off to the fender well and goes to the air pump at the front of the car.

 

[redc4corvette]

It injects air into the exaust and intake manifolds,All air comes from your electric air injection pump on the driverside next to the radiator,Lots of long rubber black hoses.

 

[SSTibet]

The seconday air injection system (AIR) injects air to the exhaust, I know that much. But I did not know it also injects air into the intake manifolds???

So air intake into the compression chamber is from 2 sources = (1) throttle body, and (2) AIR system ??? I have a hard time believing this, sorry... Unless the AIR air is blown into the crankcase for ventilation...

 

[redc4corvette]

You have an air pump at the front of the drivers side and a rubber hose runs from the air pump to a fitting ,that is inline which has a spong on a little fitting about an 1/8 inch in diam.
The hose goes to a tee that branches off to the right and left at this point, the left connects to a metal line that goes into the center of the top of the manifold exaust with a back fire valve on it.
The right goes to a metal pipe which connects with two bolts next to the EGR valve ,the metal pipe continues to the pass side exaust manifold and one more back fire valve in the center of the manifold (exaust).Yes it does blow air into the intake manifold at the rear of the engine.
If you have an lt1 this is the routing for the llines
The L98 is nothing like an LT1 and it hooks into an L98 totally different!!
I have both!
I think your car is a 95?
It would be the same as my 94?

 

[SSTibet]

Okay, mine is a 95 with an LT-1 engine. Must be similar to 94.

And thanks for the description. Now the 1 million dollar question about the secondary air going into the intake manifold... :naughty: Does this air go to the combustion chambers (i.e. cylinders) or is it used for ventilation of the crankcase??? :J Or, some other function???

Cheers,

Selim

 

[redc4corvette]

Well is a deep question.
The 94 to 97 LT1 only had an EGR and the air injection motor to lean out the exaust by blowing air into the exaust manifolds sometimes to heat the 3 o2 sensors ,so they would heat up quicker.
The other is to lean out the fuel in the intake manifold to meet smog requirements in California and other states.
The LT4 does not have an EGR valve and it has more horse power ,with a bigger cam and with the overlap , the egr was not used because it could meet smog requirements without an egr valve and injection pump.
Im would buy the lt4 manifold and heads and do away with all that junk.

 

[SSTibet]

You are getting me more & more confused here. My question does not relate to EGR; I am pretty clear on how the EGR works, what parts of the engine do the EGR function, etc etc etc.

The question is about "secondary air injection system (AIR)" blowing air into the intake manifold. Does that injected air into the manifold go to the compression chambers or is it used to ventilate the crank case?

Cheers,

Selim

 

[redc4corvette]

Yes it blows air into the intake to lean the engine fuel.

Or it will lower your lmtrim from 128 to 120.

 

[SSTibet]

"lmtrim from 128 to 120" ??? What does "Imtrim" mean???

 

[redc4corvette]

If you have tts or tuner cats you can reprogram your computer.

 

[G Winter]

The air injection pump puts fresh air into the exhaust mainfolds and sometimes the cat. With the heat that is there it helps to finish burning any unburned feul in the exhaust. Thus helping to meet emission standards . Air going into the intake is something I haven't studied. so I can't help there .

 

[SSTibet]

I am quite puzzled that air is injected into the intake path of air & fuel since this sounds quite uncontrolled... Just blow air into the intake; pufffff - just like that??? What happens to air / fuel ratio, MAF & MAP adjustments / signals to the ECM???

On the one hand I read a closed loop system where the air / fuel ratio is controlled with many sensors and the ECM, on the other hand I am hearing that air is being injected into the same stream in a rather uncontrolled fashion...

I AM CONFUSED...

P.S. What does "Imtrim" stand for???