TBI sensor diagram please
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Joined: Aug 2004
Posts: 708
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From: Upstate New York
Car: 1988 SC Camaro
Engine: 305 TBI
Transmission: 700-R4
TBI sensor diagram please
maybe someone has already posted/has this, but it would be helpful if someone could please post a diagram/picture of all the sensors in the engine bay...or if someone could guide me in the right direction...thanks
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From: Cincinnati, OH
Car: '90 RS
Engine: 377 LSX
Transmission: Magnum T56
Which ones do you need? I guess I could put one together later. There is a TBI diagram in the new to TBI sticky above to get you started.
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From: Upstate New York
Car: 1988 SC Camaro
Engine: 305 TBI
Transmission: 700-R4
ok, thanks....and i just remembered, i do have a chilton's manual...I will check in there as well...can someone tell me about the difficulty in changing the EGR valve?...and the TPS as well? (although GM told me today that the TPS is not "servicable"...i was thining abouyt changing these two thing out to see if it correct the idle problem I've had for a year now
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Joined: Feb 2004
Posts: 1,231
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From: Greenville, SC
Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
This should help a little:
http://www.autozone.com/images/cds/g...3d801637bb.gif
Replacing the EGR valve and the TPS is not hard at all, but why exactly do you want to change them? Are you getting codes for a bad EGR valve or TPS?
Care to elaborate on your idle problem?
Don't go replacing parts just yet.
http://www.autozone.com/images/cds/g...3d801637bb.gif
Replacing the EGR valve and the TPS is not hard at all, but why exactly do you want to change them? Are you getting codes for a bad EGR valve or TPS?
Care to elaborate on your idle problem?
Don't go replacing parts just yet. Last edited by Benm109; Jul 26, 2005 at 01:05 PM.
Thread Starter
Senior Member
Joined: Aug 2004
Posts: 708
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From: Upstate New York
Car: 1988 SC Camaro
Engine: 305 TBI
Transmission: 700-R4
well, I've has this "surging" idle problem for a while, and i had the car hooked up to the computer diagnostic machine and the people there "think" it might be an EGR problem, but they're not sure...and there was no codes thrown by the diagnostic computer....so i really don't know for sure what the problem might be...the car will idle normally for a few seconds (4-6 second) and then go down a bit and then surge back up...my Induction manafold was changed a while back and i thought that might have something to do with it....what do you think?
Thread Starter
Senior Member
Joined: Aug 2004
Posts: 708
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From: Upstate New York
Car: 1988 SC Camaro
Engine: 305 TBI
Transmission: 700-R4
the mechanics couldn't find anything wrong with the car, but they admitted that the problem was there...the newer manafold is the edelbrock one that can be seen on the TBI Sticky page...
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Supreme Member
Joined: Feb 2004
Posts: 1,231
Likes: 1
From: Greenville, SC
Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
....what do you think?
But, first off, how long has it been since the car has had a good tune-up (spark plugs, spark plug wires, distributor cap and rotor, PCV valve, air filter, fuel filter, etc.)? Does the "check engine light" ever come on? If so, what codes are showing up?
Also, since the manifold has been replaced, it might be worth it to go back over everything you (or the shop) did. It's easy to miss vacuum lines or electrical connectors sometimes when doing something like an intake swap. Just make sure everything is hooked up and looks correct.
Last edited by Benm109; Jul 26, 2005 at 01:47 PM.
Thread Starter
Senior Member
Joined: Aug 2004
Posts: 708
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From: Upstate New York
Car: 1988 SC Camaro
Engine: 305 TBI
Transmission: 700-R4
the check engine light has come on a few times while driving the car, but still no codes showed up on the diagnostic computer...and the car has had new plugs, wires and O2 sensor....the rotor looks good, although it may not have been changed in the past few years...anything else i can do?....I'd really like to get this problem fix w/in the next few days...thanks for the help
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Joined: Feb 2004
Posts: 1,231
Likes: 1
From: Greenville, SC
Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
Next thing I would recommend is to remove and clean the IAC valve, and see if that helps (it's also free ). Over time IAC valves get gummed with carbon and other junk that can cause them to stick or not fully seat. It would also be a good idea to check out and clean the IAC passage on the TBI unit while it's out.
I'm stealing this from dimented24X7:
). Over time IAC valves get gummed with carbon and other junk that can cause them to stick or not fully seat. It would also be a good idea to check out and clean the IAC passage on the TBI unit while it's out.I'm stealing this from dimented24X7:
In addition to this, I want to clean my IAC. How can I do this?
1). Remove the IAC. It can be found on the pass side of the tbi. See the link below for an expanded view of the IAC...
http://216.121.161.76/files/TBI220.jpg
[Thanks Vader!]
2). After you have done so, reconnect the IAC connector and place a bag or towel around the IAC so the pintle doest go flying off. Once this is done, jumper pins 'A' + 'B' in the ALDL connector. Once jumpered, turn the key to the ON position, but dont start the car. The ecm will eject the IAC pintle. Turn off the ignition and remove the IAC and its compontents.
3). Next step is to clean the parts. I like using lighterfluid or naphtha. Cleans and leaves no unpleasent odor once it evaporates. NEVER use harsh solvents or dip in/spray the IAC with cleaners!!! It may be damaged! Use a toothbrush to remove all the carbon deposits from the guide, spring, and the threads on the pintle shaft. Once dry lightly coat the pintle shaft and guide with a light grease or oil.
4). Reassemble. Place the spring over the pintle and place the pintle shaft in the guide slot in the IAC. It wont jsut go in as there is an armature with gear teeth on it. Screw the IAC pintle in untill the guide slots on the pintle shaft just meet up with the guides in the IAC main body. From there gently rock the IAC pintle back and fourth while applying light pressure untill the pintle gets partially back into the IAC.
5.) Reinstall the IAC. Screw it in by hand and if you feel any sort of resistance, STOP!!! The pintle has bottomed out. Reconnect the IAC and pull the jumper out of the ALDL if you have not yet done so. Lightly depress the gas pedal and start the car. Let it run for about 30 secs and shut down. Do the following to tighten the IAC:
As posted by Vader:
quote:
--------------------------------------------------------------------------------
You can use a wrench, but remember that the torque specification for an IAC is 13 ft/lb for '85-'89 , 30 in/lb for 1990-on, or not very much torque at all. Hand tight and about 1/16 additional turn is about all that's necessary.
--------------------------------------------------------------------------------
And your done! The vehicle is ready for use. I do this every 6000 miles or so to keep the IAC clean and moving freely. This is a good idea as a sticky IAC will cause delayed responces to the ECMs commands.
1). Remove the IAC. It can be found on the pass side of the tbi. See the link below for an expanded view of the IAC...
http://216.121.161.76/files/TBI220.jpg
[Thanks Vader!]
2). After you have done so, reconnect the IAC connector and place a bag or towel around the IAC so the pintle doest go flying off. Once this is done, jumper pins 'A' + 'B' in the ALDL connector. Once jumpered, turn the key to the ON position, but dont start the car. The ecm will eject the IAC pintle. Turn off the ignition and remove the IAC and its compontents.
3). Next step is to clean the parts. I like using lighterfluid or naphtha. Cleans and leaves no unpleasent odor once it evaporates. NEVER use harsh solvents or dip in/spray the IAC with cleaners!!! It may be damaged! Use a toothbrush to remove all the carbon deposits from the guide, spring, and the threads on the pintle shaft. Once dry lightly coat the pintle shaft and guide with a light grease or oil.
4). Reassemble. Place the spring over the pintle and place the pintle shaft in the guide slot in the IAC. It wont jsut go in as there is an armature with gear teeth on it. Screw the IAC pintle in untill the guide slots on the pintle shaft just meet up with the guides in the IAC main body. From there gently rock the IAC pintle back and fourth while applying light pressure untill the pintle gets partially back into the IAC.
5.) Reinstall the IAC. Screw it in by hand and if you feel any sort of resistance, STOP!!! The pintle has bottomed out. Reconnect the IAC and pull the jumper out of the ALDL if you have not yet done so. Lightly depress the gas pedal and start the car. Let it run for about 30 secs and shut down. Do the following to tighten the IAC:
As posted by Vader:
quote:
--------------------------------------------------------------------------------
You can use a wrench, but remember that the torque specification for an IAC is 13 ft/lb for '85-'89 , 30 in/lb for 1990-on, or not very much torque at all. Hand tight and about 1/16 additional turn is about all that's necessary.
--------------------------------------------------------------------------------
And your done! The vehicle is ready for use. I do this every 6000 miles or so to keep the IAC clean and moving freely. This is a good idea as a sticky IAC will cause delayed responces to the ECMs commands.
Last edited by Benm109; Jul 28, 2005 at 09:54 AM.
Thread Starter
Senior Member
Joined: Aug 2004
Posts: 708
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From: Upstate New York
Car: 1988 SC Camaro
Engine: 305 TBI
Transmission: 700-R4
and i can't find the EGR valve in the chilton's....only the step by step install for the TPS....is there any guide for the EGR?
Last edited by Crusin' 1980's; Jul 28, 2005 at 10:04 AM.
Supreme Member
Joined: Feb 2004
Posts: 1,231
Likes: 1
From: Greenville, SC
Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
The EGR valve is on the rear of the intake manifold, pretty much right in between the TBI unit and the distributor.
If you look right behind the TBI unit in these pictures, you'll see it. It's the gold saucer-shaped thing bolted to the intake:
If you look right behind the TBI unit in these pictures, you'll see it. It's the gold saucer-shaped thing bolted to the intake:
Last edited by Benm109; Jul 28, 2005 at 10:05 AM.
Thread Starter
Senior Member
Joined: Aug 2004
Posts: 708
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From: Upstate New York
Car: 1988 SC Camaro
Engine: 305 TBI
Transmission: 700-R4
ok, the picture was very helpfull, thanks....any chance you could also show me where the TPS is located?...it might even be shown in the picture, I'm not sure
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Joined: Feb 2004
Posts: 1,231
Likes: 1
From: Greenville, SC
Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
Yep, it's in the second picture I posted. If you look at the passenger side of the TBI unit, you'll see 2 parts with wires going to them. The gold part is the IAC valve, and the gray part is the TPS.
You can see it in this picture as well:
EDIT: Are the pictures still showing up for you? All the sudden I can't see them on my computer.
You can see it in this picture as well:
EDIT: Are the pictures still showing up for you? All the sudden I can't see them on my computer.
Last edited by Benm109; Jul 28, 2005 at 10:22 AM.
[/IMG] 
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Joined: Sep 2002
Posts: 102
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From: Austin
Car: 87 Wrangler
Engine: 355 TBI
Transmission: 700R4
egr connections
where do the egr connections go. i know the front passenger line goes where? And the vacumm hose on the actual egr valve goes where? And finally, the electronic guy mounted on the side with two fitting on one side and one on the other connects where?
Thanks
Thanks
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Joined: Feb 2004
Posts: 1,231
Likes: 1
From: Greenville, SC
Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
Re: egr connections
Originally posted by mylittlemule
where do the egr connections go. i know the front passenger line goes where? And the vacumm hose on the actual egr valve goes where? And finally, the electronic guy mounted on the side with two fitting on one side and one on the other connects where?
Thanks
where do the egr connections go. i know the front passenger line goes where? And the vacumm hose on the actual egr valve goes where? And finally, the electronic guy mounted on the side with two fitting on one side and one on the other connects where?
Thanks
You know what they say, a picture's worth a thousand words:
http://www.autozone.com/images/cds/g...3d8016381c.gif
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Joined: Sep 2002
Posts: 102
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From: Austin
Car: 87 Wrangler
Engine: 355 TBI
Transmission: 700R4
allright. i connected the egr the way the diagram showed and all sorts of bad things started happening. crazy loping. i've since disconnected the entire egr system and it runs a little better.
still no full throttle or hard hits on the pedal. why? when i do hit the petal it sounds like a choking monster and gives no acceleration until i back off the throttle. why?
here is what i have done.
1. tps voltage starts at.54 and at full throttle of the gas pedal it is at 4.13
2. reset the iac and base timing to 450 rpm
3. knocked down the timing from 8 degrees to 2 in 2 degree increments. this might have helped a little, but i still have the problem
4. checked the engine codes. it only said hello and goodbye
what is next?
still no full throttle or hard hits on the pedal. why? when i do hit the petal it sounds like a choking monster and gives no acceleration until i back off the throttle. why?
here is what i have done.
1. tps voltage starts at.54 and at full throttle of the gas pedal it is at 4.13
2. reset the iac and base timing to 450 rpm
3. knocked down the timing from 8 degrees to 2 in 2 degree increments. this might have helped a little, but i still have the problem
4. checked the engine codes. it only said hello and goodbye
what is next?
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Joined: Feb 2004
Posts: 1,231
Likes: 1
From: Greenville, SC
Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
mylittlemule, what exactly is the problem with your car? Sounds like the car won't take any throttle. So it's just choking and idling erraticly at idle? How long has the car been acting like this. Are you actually able to drive it, or is the problem too bad? Just wanting to make sure I fully understand the problems your having.
First things first, how long has it been since the car's had a full tune-up (spark plugs, spark plug wires, distributor cap and rotor, fuel filter, air filter, PCV valve, etc.)?
First things first, how long has it been since the car's had a full tune-up (spark plugs, spark plug wires, distributor cap and rotor, fuel filter, air filter, PCV valve, etc.)?
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Joined: Sep 2002
Posts: 102
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From: Austin
Car: 87 Wrangler
Engine: 355 TBI
Transmission: 700R4
it has been parked forever. I pulled the plugs last nightand found that at on point they were brown, but now they are white.
Pcv checked out okay and i'm on the way to get another fuel pump. the brand new one is very noisy.
the car is driveable just no stomping on the throttle. i can get away with just being gentle all day, but that is no fun.
my fuel pressure is of concern to me. i'm going to do the plugs, cap, and rotor. then i'm going to check the fuel pressure again.
Pcv checked out okay and i'm on the way to get another fuel pump. the brand new one is very noisy.
the car is driveable just no stomping on the throttle. i can get away with just being gentle all day, but that is no fun.
my fuel pressure is of concern to me. i'm going to do the plugs, cap, and rotor. then i'm going to check the fuel pressure again.
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From: Upstate New York
Car: 1988 SC Camaro
Engine: 305 TBI
Transmission: 700-R4
BENM109
can you tell me if the spring needs to be revomed behind the TPS?...i moved it with my hand and it seems ok from what i can tell, although i don't know much about it...also, could you help me identify these two plugs that are labeled in the pic? thanks for your help thus far
[IMG]
[/IMG]
[IMG]
[/IMG] Supreme Member
Joined: Feb 2004
Posts: 1,231
Likes: 1
From: Greenville, SC
Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
my fuel pressure is of concern to me. i'm going to do the plugs, cap, and rotor. then i'm going to check the fuel pressure again.
can you tell me if the spring needs to be revomed behind the TPS?...i moved it with my hand and it seems ok from what i can tell, although i don't know much about it...also, could you help me identify these two plugs that are labeled in the pic? thanks for your help thus far
The 1st item is the electrical connector for the MAP sensor. It has a 3-wire connector and 1 vacuum line coming out of it. I don't see the vacuum line in your picture (it might be hidden in the pic, though), did you remove it? If not, that might be part of your problem. The vacuum line should run from the bottom of the MAP sensor (right behind the electrical connector) to the 1 vacuum port on the back of the TBI unit (right in between the fuel line fittings).
The 2nd item is the electrical connector for the EGR solenoid. It just has a 2-wire connector and has 2 vacuum lines coming out of it.
Supreme Member
Joined: Feb 2004
Posts: 1,231
Likes: 1
From: Greenville, SC
Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
Crusin' 1980's, I am not aware of a spring behind the TPS. Do you happen to have a picture of it? I'm having trouble visualizing what it could be.
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Posts: 708
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From: Upstate New York
Car: 1988 SC Camaro
Engine: 305 TBI
Transmission: 700-R4
ok Benm109, I'm still not through with you 
any chance you can identify this "gizmo" thing thats between the TB and the Distributor?
[IMG]
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any chance you can identify this "gizmo" thing thats between the TB and the Distributor?[IMG]
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From: Austin
Car: 87 Wrangler
Engine: 355 TBI
Transmission: 700R4
ignition coil.
that grey connector has a white and a pink wire on top of it. i know this because i am only using the other connector. i need that grey one so i can hook up my tach.
that grey connector has a white and a pink wire on top of it. i know this because i am only using the other connector. i need that grey one so i can hook up my tach.
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Joined: Feb 2004
Posts: 1,231
Likes: 1
From: Greenville, SC
Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
Yep, just keep that spring behind the TPS in place. I can't think of any reason to remove it, unless it was broken or something, but it doesn't look like it is.
The "gizmo" is the ignition coil, mylittlemule is right. Item #1 is 1 of the 2 electrical connections for the coil, item #2 is the ignition coil itself, and item #3 is the coil wire that runs to the distributor (specifically, the middle post on the distributor cap).
The "gizmo" is the ignition coil, mylittlemule is right. Item #1 is 1 of the 2 electrical connections for the coil, item #2 is the ignition coil itself, and item #3 is the coil wire that runs to the distributor (specifically, the middle post on the distributor cap).
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