L98 Sensor edjumakashun
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
L98 Sensor edjumakashun
Got my 1989 plenum off tonight. So, I thought I'd take the time out to figure out what I'm looking at. (My manual has mysteriously disappeared).
There are a few sensors I'm curious about.
1) Sensor that plugs up under the rear of the plenum.
2) Sensor that plugs into the pass side of TB (connects to TB plate).
3) Sensor below #2
4) Sensor that mounts into the front of the intake manifold
5) Sensor that has two vacuum lines jutting out of it. It sits behind the Thermostat housing.
Also, what's the giant diaphram below the plenum on the intake?
While I'm at it, two vacuum lines exit the rear of the plenum.
There are a few sensors I'm curious about.
1) Sensor that plugs up under the rear of the plenum.
2) Sensor that plugs into the pass side of TB (connects to TB plate).
3) Sensor below #2
4) Sensor that mounts into the front of the intake manifold
5) Sensor that has two vacuum lines jutting out of it. It sits behind the Thermostat housing.
Also, what's the giant diaphram below the plenum on the intake?
While I'm at it, two vacuum lines exit the rear of the plenum.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
lemme see...
1. Intake temp sensor
2. TPS
3. IAC
4. Coolant temp
5. EGR switch
Giant diaphram = fuel pressure regulator
Just that... vacuum. One goes to the FPR and the other to the climate controls.
1. Intake temp sensor
2. TPS
3. IAC
4. Coolant temp
5. EGR switch
Giant diaphram = fuel pressure regulator
Just that... vacuum. One goes to the FPR and the other to the climate controls.
Thread Starter
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Joined: Nov 2003
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
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IAC? I thought that was the gizzmo over the battery? The one that controls "off-idle" ala the old dashpots.
Also, I thought the fuel regulator was at the rear of the fuel rails. The "EGR" switch has one vacuum line going to the "giant diaphram" in the intake. I would expect it to control vents of fumes back into the intake.
gp
Also, I thought the fuel regulator was at the rear of the fuel rails. The "EGR" switch has one vacuum line going to the "giant diaphram" in the intake. I would expect it to control vents of fumes back into the intake.
gp
Last edited by GREGGPENN; Oct 21, 2007 at 12:28 AM.
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Thread Starter
Race Director
Joined: Nov 2003
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Thanks for the help! And thanks for the link. Hope I find my manual today... And, I'll try to leave the Johnson rod alone while I'm looking for it.... 
gp
gp
Thread Starter
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
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There's a diaphram-operated contraption that sits above/near the battery. It's purpose appears to be holding the motor off idle. In fact, it's the second cable going to the TB linkage.
Does the sensor in question work in conjuction with the actual IAC?
Does the sensor in question work in conjuction with the actual IAC?
Melting Slicks
Joined: Jan 2001
Posts: 2,940
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From: Chesapeake VA
I believe that is the Cruise Control actuator. It does not talk to the Idle Air Control system as far as I know.
Melting Slicks
Joined: May 2001
Posts: 3,014
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From: Raleigh, NC
The throttle linkage will be completely closed at idle. The throttle blades will be completely closed at idle.
The engine gets it's idle air through the Idle Air Control valve, which is on the bottom of the throttle body. It opens and allows air to bypass the throttle blades. If you pull off the intake duct, you can see the inlet hole in the throttle body just infront of the throttle blades. That hole leads to the IAC valve. That valve is opened and closed by the ECM, allowing air into the engine.
Thread Starter
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Still thinking about the stealth ram....
While reviewing connections, I came back to this. I don't know if the stealth ram's plenum has an intake temp sensor.
I'm referring to the plug that goes up under the rear of the plenum on my 1989. (I would kind of think the MAF could check the air temp, but that's just me thinking).
If I went to the stealth ram, I've thought about and covered the EGR. I assume I'd have to get all vacuum off the TB as well (after all theres two nipples on my plenum -- and vacuum coming off the manifold behind the thermo housing. W/o the EGR, those probably aren't necessary/used. Then there's the vapor cannister...)
If the Stealthram doesn't have vacuum, how would you handle that? How about the rear sensor?
gp
While reviewing connections, I came back to this. I don't know if the stealth ram's plenum has an intake temp sensor.
I'm referring to the plug that goes up under the rear of the plenum on my 1989. (I would kind of think the MAF could check the air temp, but that's just me thinking).
If I went to the stealth ram, I've thought about and covered the EGR. I assume I'd have to get all vacuum off the TB as well (after all theres two nipples on my plenum -- and vacuum coming off the manifold behind the thermo housing. W/o the EGR, those probably aren't necessary/used. Then there's the vapor cannister...)
If the Stealthram doesn't have vacuum, how would you handle that? How about the rear sensor?
gp
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From: The Top of Utah
Originally Posted by GREGGPENN
I'm referring to the plug that goes up under the rear of the plenum on my 1989. (I would kind of think the MAF could check the air temp, but that's just me thinking).
It is easy enough to drill and tap a few holes to accommodate sensors and fittings where none are provided. First, you need to read up on how it all works before you start changing things. Besides the FSM, there is Chevrolet fuel injection book, also. You can find the exact name, author, and where to buy it with a search.
RACE ON!!!
Thread Starter
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
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My guess was drilling/tapping may be required. I wanted to hear from experienced modders -- willing to share what they did or would do.
Race Director
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From: The Top of Utah
Originally Posted by GREGGPENN
"Too bad all this reading and posting on the forum doesn't count as an honest effort!" I'll check my service manual for how to mod a new intake......
Reading on this forum and doing searches on subjects of interest is a great way of learning, but posting and asking question after question on basics, with no effort to seek out real knowledge is just plain lazy. If you have the FSM, read and study it. If you don't, follow the link and buy one.
Not all answers posted here accurate. There was one genius that was constantly posting wrong information. One day he asked for help, and because HE couldn't figure out how to follow all the correct advice, given by many, he came unglued and cussed out all those that helped and advised him correctly. Who are you going to cuss out when some of the information turns out to be less than accurate? It is past time to put forth some effort.
RACE ON!!!
Thread Starter
Race Director
Joined: Nov 2003
Posts: 12,221
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
You are relying more than you should, on the good nature of your fellow Corvette aficionados. There is a certain amount of knowledge that is presupposed. Plus some are more willing to help those that have made an honest effort to help themselves. Asking how the A.I.R. system works when there are pages in the FSM devoted to the subject is pushing it a bit far. A question or two is one thing but for a complete tutorial, a little effort and some self help is in order.
Reading on this forum and doing searches on subjects of interest is a great way of learning, but posting and asking question after question on basics, with no effort to seek out real knowledge is just plain lazy. If you have the FSM, read and study it. If you don't, follow the link and buy one.
Not all answers posted here accurate. There was one genius that was constantly posting wrong information. One day he asked for help, and because HE couldn't figure out how to follow all the correct advice, given by many, he came unglued and cussed out all those that helped and advised him correctly. Who are you going to cuss out when some of the information turns out to be less than accurate? It is past time to put forth some effort.
RACE ON!!!
Reading on this forum and doing searches on subjects of interest is a great way of learning, but posting and asking question after question on basics, with no effort to seek out real knowledge is just plain lazy. If you have the FSM, read and study it. If you don't, follow the link and buy one.
Not all answers posted here accurate. There was one genius that was constantly posting wrong information. One day he asked for help, and because HE couldn't figure out how to follow all the correct advice, given by many, he came unglued and cussed out all those that helped and advised him correctly. Who are you going to cuss out when some of the information turns out to be less than accurate? It is past time to put forth some effort.
RACE ON!!!
I disagree there's a "presumption of knowledge" before posting here. There should be a forum for people who really aren't interested in answering basic questions, so you'd have a place to be happy.
The AIR pump does have basic learnable procedures (as does everything else on a car). Often finding real-world experience is what people are looking for. On this subject, I've PM'd and talked to people who think improving the factory tune can do more and compensate for this device. Other's believe it hurts more than helping after a period of carbon build-up. My exhaust shop is one of those. You will not find this in any manual.
The are many aspects not covered in manuals. I spent another hour looking for mine this week. A recent installation of wood floors in my house caused a packing and entire moving of the main floor. I have not been able to find it since then. And, I'm not buying an extra copy just to make you happy.
Since I seem to irritate you, as you do I, I invite you to help others and leave me alone (i.e., refrain from posting in my threads). I don't want/need your help.
RACE OFF!!! (as in away)
Last edited by GREGGPENN; Oct 26, 2007 at 06:14 PM. Reason: clarify salutation
Race Director
Joined: Sep 2000
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From: The Top of Utah
Originally Posted by GREGGPENN
I disagree there's a "presumption of knowledge" before posting here.
Originally Posted by GREGGPENN
The are many aspects not covered in manuals. I spent another hour looking for mine this week.
Originally Posted by GREGGPENN
Got my 1989 plenum off tonight. So, I thought I'd take the time out to figure out what I'm looking at. (My manual has mysteriously disappeared). [You wouldn't recognize it if you saw it]
There are a few sensors I'm curious about.
1) Sensor that plugs up under the rear of the plenum.
2) Sensor that plugs into the pass side of TB (connects to TB plate).
3) Sensor below #2
4) Sensor that mounts into the front of the intake manifold
5) Sensor that has two vacuum lines jutting out of it. It sits behind the Thermostat housing.
Also, what's the giant diaphram below the plenum on the intake?
While I'm at it, two vacuum lines exit the rear of the plenum.
There are a few sensors I'm curious about.
1) Sensor that plugs up under the rear of the plenum.
2) Sensor that plugs into the pass side of TB (connects to TB plate).
3) Sensor below #2
4) Sensor that mounts into the front of the intake manifold
5) Sensor that has two vacuum lines jutting out of it. It sits behind the Thermostat housing.
Also, what's the giant diaphram below the plenum on the intake?
While I'm at it, two vacuum lines exit the rear of the plenum.
Does the sensor in question work in conjuction with the actual IAC?." Give me a break!
RACE ON!!!