89 TPI Throttle Body Question
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,257
Likes: 4
From: North Carolina
89 TPI Throttle Body Question
Hello
Working on my car the other day i noticed that underneath the throttle body on my 89 L98 Vette, there is a port that sticks out. I am assuming its some type of vacuum port... well there was nothing attached to it, it was just open. Anyone know what it does or where its supposed to plug into?
DG
Working on my car the other day i noticed that underneath the throttle body on my 89 L98 Vette, there is a port that sticks out. I am assuming its some type of vacuum port... well there was nothing attached to it, it was just open. Anyone know what it does or where its supposed to plug into?
DG
Melting Slicks
Joined: Apr 2002
Posts: 2,118
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From: St. Charles, MO Route 66 Corvette Club
Dan:
Does this open port point toward the radiator? If so......it is a coolant nipple and someone had done a throttle body bypass on your car. Consider yourself lucky if this is the case!
Bob
Does this open port point toward the radiator? If so......it is a coolant nipple and someone had done a throttle body bypass on your car. Consider yourself lucky if this is the case!
Bob
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
If it's small and pointing straight down, it goes to the EGR switch via a "U" shaped hard vacuum line. To know for sure, start the car and put your finger over the port and check for vacuum.
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,257
Likes: 4
From: North Carolina
Would this at all effect the idle... just wondering?
Dan
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,257
Likes: 4
From: North Carolina
Let me rephrase that question... I know that vacuum leaks can effect idle. I thought there was a possiblity that it might be some sort of vacuum port so I pluged it for the time being. I have been trying to trace down for the past couple of months, why my car jumps down to 600 RPM when I come to a stop at a stop light and then bounces up to 900RPM's finally settling down at around 800RPM... If there was a vaccuum line there at some point, there are 2 ends to it so i just wanted to know where the other end went, figuring maybe that other end was causing a problem.
If I am not making any sense (and i usually don't); right now the tube sticking out of the bottom of the throttle body is plugged. I just want to know what exactly it does and where it leads to.
DG
If I am not making any sense (and i usually don't); right now the tube sticking out of the bottom of the throttle body is plugged. I just want to know what exactly it does and where it leads to.
DG
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
As I said, it leads to the EGR switch that is right under the TB via a "U" shaped vacuum line. This switch gets vacuum from said port, and cuts/feeds it to the EGR valve at the appropriate times.
EGR switch is bolted next to thermostat housing below TB. That port under the TB goes to one of the two ports on the EGR switch below. The other port on the switch then feeds to the EGR valve under the plenum mounted on the center of intake base.
EGR switch is bolted next to thermostat housing below TB. That port under the TB goes to one of the two ports on the EGR switch below. The other port on the switch then feeds to the EGR valve under the plenum mounted on the center of intake base.
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Team Owner
Joined: May 2002
Posts: 24,337
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Your car will never idle right with that port unplugged. Check your radiator shroud for a vacuum line diagram.
After you have everything together, recalibrate the idle. Do a search for "base idle" or "idle set" and you'll find out how.
After you have everything together, recalibrate the idle. Do a search for "base idle" or "idle set" and you'll find out how.
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,257
Likes: 4
From: North Carolina
As I said, it leads to the EGR switch that is right under the TB via a "U" shaped vacuum line. This switch gets vacuum from said port, and cuts/feeds it to the EGR valve at the appropriate times.
EGR switch is bolted next to thermostat housing below TB. That port under the TB goes to one of the two ports on the EGR switch below. The other port on the switch then feeds to the EGR valve under the plenum mounted on the center of intake base.
EGR switch is bolted next to thermostat housing below TB. That port under the TB goes to one of the two ports on the EGR switch below. The other port on the switch then feeds to the EGR valve under the plenum mounted on the center of intake base.
Looking at the picture you sent me, there are only two ports on that switch. If one of those lines is leading from the EGR to the switch, and the other is leading from the switch to the throttle body, then where would the line leading to the charcoal canister connect to?
I can supply pictures tomorrow if necessary,
Dan
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,257
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From: North Carolina
Ill check it out tomorrow and let you know how it works out.
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,257
Likes: 4
From: North Carolina
Pacer 86... thanks again for the help...
Ill talk to you guys tomorrow night, I have to go get some sleep... early morning tomorrow.
DG
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,257
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From: North Carolina
Awesome!!!
(Save and Print....)
Among the upgrades I got with this car were, the taped in K&N air filter, the air foil mod, a clifford remote window roll down unit (that wasn't working) and lets not forget the microphones taped all over the car.
DG
(Save and Print....)
Among the upgrades I got with this car were, the taped in K&N air filter, the air foil mod, a clifford remote window roll down unit (that wasn't working) and lets not forget the microphones taped all over the car.
DG
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Er.. I mean to say, you're welcome! On my 85 the tee is made of rubber and the EGR hard plastic line goes to it, on the otherside is a short hard line that goes to a barbed connection, on there goes a hose to the vapor canister.
I think the parts stores only have hard plastic vacuum tees. So get that and some vacuum tubing. Would be a good time to replace them all if you haven't already.
