What is the port located between the 3rd and 5th runner for?

 

i'm thinking... EGR? connects EGR valve "output" with plenum passages trough thin "9th runner".

 

Is this the area you are talking about? if so, it is the port connection for the PCV valve.

 

Although your description isn't clear, wouldn't the runner between the 3rd and 5th runner be the 4th runner

The only other openings on the runners are for EGR passage or the cold start port. The small tubes runnning next to the large runners are EGR.

My bad were talking about the base. Maybe PCV as Trickster suggested, or it could still be the EGR opening.

 

Thanks Trickster, as they say a pic is worth a thousand words. Guess I know what to use for PCV now.

 

You're welcome Fevre!!!!!!!!!!

 

Since you are on a roll, what is the port on the TB that is located below the fresh air port for? It was capped off when I bought the car.

 

It is for coolant and used to have a hose going to the heater control valve. The circled "X: at the front of the throttle body is where the coolant enters the base of the throttle body from the hose at the front of the manifold. Rolling, rolling, rolling

 

The carbon canister connects to the vacuum port on the side of the throttle body right underneath the fresh air port. Then you have the coolant passage underneath that... Heck while we're on the throttle body port kick, the port on the very bottom of the throttle body is ported vacuum for the egr valve.

 

That is the one! Thanks for the info, will have to check my hose routings, that was capped when I bought the car.

 

Fresh Air?

Mine has been renamed the PCV port on the throttle body since it is used as such.

 

Yep, that opening marked fresh air sends fresh air from the throttle body to the breather valve on the passenger side valve cover. If you are using that as the PCV port it won't do a very good job as you require a vacuum source and that is not one.

 

Tricksters got it right, if your PCV was moved from the drivers side to the passenger side and you connected it to that "air in" port on the TB your PCV is no longer doing its job. You can switch the side you pcv is on, but the PCV valve itself needs vacuum you can route the hose around the back of intake and connect it to the vacuum port from the drivers side. You have to have a breather on the opposite side valve cover of the PCV still. Without an opposite side breather and PCV to vacuum port it can not function properly. You may not see any evident problems at the moment but that doesn't mean its healthy for your engine.

 

Cool learned something. Mine is hooked up right, I just assumed it was PCV.

Charlie

 

So the large "Fresh Air" port on the Pass side of the TB is supposed to be capped then? My PCV is on the drivers side and there is a chrome breather on the pass side.

Also, where does the "Fresh Air" port get its air? I would assume it just diverts some of the incoming airflow to the breather? Or is it from another source?

 

You got it!!!!!!!!!!!!!!!

 

Yes if your using an aftermarket type push in breather then you should cap the one on the TB.

If you mean the TB "fresh air" port it recieves incoming air from the TB cavity itself.

 

Dang beat to the punch by Trickster again, thats twice now in different post I have been typing a response and by the time I am done I see your post right in front of me. Your just to damn good Trickster:hail:

 

So it wouldn't be a vacuum leak if not plugged or connected? Wouldn't it make the engine run differently?

 

I doubt it would affect anything except leaving an opening for dirt or spiders to get in. Its not vacuum.

 

OK...but on a MAF car, the MAF is reading X amount of air entering the engine, and so my question here (since the original question is for an 89 TPI setup) is that is this a problem?

 

What are you looking to setup there 88TPI406GTA, a TPI or TBI. The 89 TPI engines had the MAF as well as the 2.8L V6. The 5.0L (LO3) had the MAP system. The same thing applies to 90 and higher year model cars that have the TPI and MAP. Fresh air is routed from the Throttle body intake out the fresh air port to the breather valve on the passenger side valve cover.

 

Actually, my question was theoretical. On my 91 (the same one I was having issues with the PCV Valve on) this port was open and I plugged it...it didn't really impact the engine running.

My theoretical question on a MAF setup was more to understand that there should be no air lost/gained after the MAF due to its accounting (roughly) for the amount of air that passes through it.

 

It won't neccessarily impact the MAF because it has already gone beyond that point. Where it would impact the MAF would be if you had an opening in the air duct prior to the MAF other than the air filter or running without air filters.

 

Trickster...I hate to say this, but what you said makes no sense.

What I am talking about is a loss of air from or possibility into the system AFTER the MAF. Meaning that the MAF sees x amount of air and the "fresh air" port "leaks" out say 10% of that air. The ECM calculation will be off by that 10%.

This is analagous to running a Y inlet with the MAF on one side and the other end open...the MAF would only see 1/2 of the air coming into the engine.

My question rather was since the TB is AFTER the MAF, shouldn't it affect the ECM load calculation because roughly 10% less air is actually being fed into the engine, thereby making it richer?

The MAF system on our cars is a coarse system though and a little leak like this probably won't matter...otherwise it would have been a bigger issue already.

See where I am going with this?

 

I'm not really sure why you are asking about the MAF when your car is designed and set-up with MAP. By plugging that port, what you are doing is increasing the pressure in the manifold by stopping the air from going to the breather valve from the throttle body. On the cars with MAF, that air is diverted at the throttle body after it has already been measured by the MAF sensor. The MAf sensor only measures air going through it, not what has already gone through it.

 

I am curious because the GTA IS a MAF car...and I had never heard of this port before...

I guess that the stock MAF tables must take this into account then...

 

Hey 88TPI406GTA, The amount of air that can pass through that port is so minimal it would not affect the MAF readings enough to make a difference. There is no direct open port for air to be forced through on the TB port opening, Its more a series of passages to be able to draw air from designed into the cavity of the TB. So to answer your question simply theres just not enough air lost through that port passage to affect the readings from your MAF. It should be capped just to keep the inside clean.

 

I think that part of my past experience is from newer MAF engines...like a 95 Eagle Talon I owned. It was the turbo 2.0, 5 speed, AWD. Basically I remember that there was an issue with the Blowoff Valve. The stock setup recycles back into the intake behind the MAF and some guys were venting to atmosphere. That was a bad idea and caused some real drivability issues. This was under boost and a different ECM, but I thought that the principle was the same.