Adjusted Minimum Air, TPS, something is still wierd
12-08-2001, 01:16 PM
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Car: 1988 IROC-Z
Engine: 5.7L TPI
Transmission: 700R4
Axle/Gears: BW 2.77
Adjusted Minimum Air, TPS, something is still wierd
I had cleaned the IAC valve about a year ago. Maybe I should pull it out again, but it's not like the runs bad at all.
I jumpered the test contacts on the ALDL, turned on the car and let it sit 30 seconds. Then disconnected the IAC valve. Tried to start it and it wouldn't start. I adjusted the throttle up a ways to where it would finally run. Using my RPM diagnostics gauge, I tuned it down to 400 RPM (88 IROC 350 Auto). Shut it off, removed the jumper, and then proceeded to adjust the TPS to 0.540VDC again.
Well, I noticed that I had to move the idle control screw to where it's almost twice out as it was before and now the TPS won't go above 3.5VDC.
The throttle response when you give it gas is kind of a rough, kinda starving response then goes. It idles fine, driving is fine, just the throttle response is a little on the harsh side. I was playing with it a couple of days ago and it was actually responsing really good until I decided to "adjust it right" Any ideas? Or just live with it ... bleh!
------------------
IROCZONE
------------------
'88 Camaro IROC-Z 350 TPI
"Yea, though I walk through the valley of rice,
I shall fear no Turbo; for Torque art with me."
- Cullan Hooley
I jumpered the test contacts on the ALDL, turned on the car and let it sit 30 seconds. Then disconnected the IAC valve. Tried to start it and it wouldn't start. I adjusted the throttle up a ways to where it would finally run. Using my RPM diagnostics gauge, I tuned it down to 400 RPM (88 IROC 350 Auto). Shut it off, removed the jumper, and then proceeded to adjust the TPS to 0.540VDC again.
Well, I noticed that I had to move the idle control screw to where it's almost twice out as it was before and now the TPS won't go above 3.5VDC.
The throttle response when you give it gas is kind of a rough, kinda starving response then goes. It idles fine, driving is fine, just the throttle response is a little on the harsh side. I was playing with it a couple of days ago and it was actually responsing really good until I decided to "adjust it right" Any ideas? Or just live with it ... bleh!
------------------
IROCZONE
------------------
'88 Camaro IROC-Z 350 TPI
"Yea, though I walk through the valley of rice,
I shall fear no Turbo; for Torque art with me."
- Cullan Hooley
12-08-2001, 02:52 PM
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Car: 1988 IROC-Z
Engine: 5.7L TPI
Transmission: 700R4
Axle/Gears: BW 2.77
Eh ... I just took it out for a test drive ... would like to see what she can do when the ECM detects WOT, but damn ... felt good anyway! 
12-08-2001, 06:17 PM
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Car: 1988 Trans Am GTA
Engine: 5.0 TPI
Transmission: TH700-R4
Axle/Gears: 3.27
To get the TPS to read 4VDC you might have to play with it a little bit. Try loosening both screws and slide the sensor forward. Then tighten the bottom some and use the top screw to do your final adjustment.
This might work since the tang on the throttle body shaft point forward while closed and rotates 90 deg. down when open. If the TPS is has some play in the screw slots, and it slides back, the tang will not rotate the sensor all the way. Sliding it forward even if it's a small amount can give you a few more milliamps without altering the low end.
BTW, if you had to screw the minimum idle screw in some more than before then the PCV valve could be blocked. The air entering the engine while at idle comes from the IAC and the PCV. If the PCV is blocked while you were adjusting the TB then your adjustment was compensating for the blockage. It is always a good idea to replace the PCV or make sure it is in good condition when adjusting the minimum idle speed.
[This message has been edited by Ozzy88GTA (edited December 08, 2001).]
This might work since the tang on the throttle body shaft point forward while closed and rotates 90 deg. down when open. If the TPS is has some play in the screw slots, and it slides back, the tang will not rotate the sensor all the way. Sliding it forward even if it's a small amount can give you a few more milliamps without altering the low end.
BTW, if you had to screw the minimum idle screw in some more than before then the PCV valve could be blocked. The air entering the engine while at idle comes from the IAC and the PCV. If the PCV is blocked while you were adjusting the TB then your adjustment was compensating for the blockage. It is always a good idea to replace the PCV or make sure it is in good condition when adjusting the minimum idle speed.
[This message has been edited by Ozzy88GTA (edited December 08, 2001).]
12-08-2001, 08:28 PM
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Car: 1988 IROC-Z
Engine: 5.7L TPI
Transmission: 700R4
Axle/Gears: BW 2.77
<font face="Verdana, Arial" size="2">Originally posted by Ozzy88GTA:
To get the TPS to read 4VDC you might have to play with it a little bit. Try loosening both screws and slide the sensor forward. Then tighten the bottom some and use the top screw to do your final adjustment.
This might work since the tang on the throttle body shaft point forward while closed and rotates 90 deg. down when open. If the TPS is has some play in the screw slots, and it slides back, the tang will not rotate the sensor all the way. Sliding it forward even if it's a small amount can give you a few more milliamps without altering the low end.
BTW, if you had to screw the minimum idle screw in some more than before then the PCV valve could be blocked. The air entering the engine while at idle comes from the IAC and the PCV. If the PCV is blocked while you were adjusting the TB then your adjustment was compensating for the blockage. It is always a good idea to replace the PCV or make sure it is in good condition when adjusting the minimum idle speed.
[This message has been edited by Ozzy88GTA (edited December 08, 2001).]</font>
To get the TPS to read 4VDC you might have to play with it a little bit. Try loosening both screws and slide the sensor forward. Then tighten the bottom some and use the top screw to do your final adjustment.
This might work since the tang on the throttle body shaft point forward while closed and rotates 90 deg. down when open. If the TPS is has some play in the screw slots, and it slides back, the tang will not rotate the sensor all the way. Sliding it forward even if it's a small amount can give you a few more milliamps without altering the low end.
BTW, if you had to screw the minimum idle screw in some more than before then the PCV valve could be blocked. The air entering the engine while at idle comes from the IAC and the PCV. If the PCV is blocked while you were adjusting the TB then your adjustment was compensating for the blockage. It is always a good idea to replace the PCV or make sure it is in good condition when adjusting the minimum idle speed.
[This message has been edited by Ozzy88GTA (edited December 08, 2001).]</font>
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