Now what????
Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,699
Likes: 2
From: The Black Hole LA
Now what????
Ok, for those of you who did not see earlier posts I took apart the intake on my 86. Now I have gotten everything back together, found earlier probs with injectors (dist. plug got knocked loose). The car will not idle now. Can start the car with the filter housing and duck off and hold my hand over the throttle body and the car will idle, take my hand off and the car dies. It is like it is getting to much air, or maybe not enough fuel. I don't think it is fuel though because I can idle steady at 1400 rpm without my hand over the TB. It seems like there is a vacuum leak but I don't seem to be able to find it. I have sprayed carb cleaner all over the visible vacuum lines hoping it would rev up and there would be my leak, that didn't work. The TP sensor was never removed from the TB so I wouldn't think that it would need to be adjusted. Any info or even guesses at this point would be greatly appreciated. I am getting flustrated :mad .
[Modified by hz900, 7:41 PM 9/13/2002]
[Modified by hz900, 7:41 PM 9/13/2002]
Racer
Joined: Jul 2001
Posts: 253
Likes: 0
Re: Now what???? (hz900)
Don't you just hate when that happens :crazy:
I had something similar when I got the '86 L98 back from the GM dealership after they replaced the engine block (insurance case). :U
It didn't seem to idle right, so I checked the basics: timing was ok, tps was a little off. But when that didn't help, I did the TPS check the right way - check the base idle first.
It was at about 200 RPM. I turned it up to 450 RPM and then reset the TPS and things are better.
What I'm trying to say is to check the basics! :cheers:
I had something similar when I got the '86 L98 back from the GM dealership after they replaced the engine block (insurance case). :U
It didn't seem to idle right, so I checked the basics: timing was ok, tps was a little off. But when that didn't help, I did the TPS check the right way - check the base idle first.
It was at about 200 RPM. I turned it up to 450 RPM and then reset the TPS and things are better.
What I'm trying to say is to check the basics! :cheers:
8th Gear
Joined: Sep 2002
Posts: 8
Likes: 0
Re: Now what???? (86VetteBill)
how exactly did you adjust the base idle?? did you adjust the screw on stop on the throttle body..
(btw: I'm hz900 aka chris's roomate, and the one that figured out something was disconnected in the distributor :cheers: )
(btw: I'm hz900 aka chris's roomate, and the one that figured out something was disconnected in the distributor :cheers: )
Racer
Joined: Jul 2001
Posts: 253
Likes: 0
Re: Now what???? (bdu1234)
High level here on my '86 L98...
Engine is warmed up and the timing is verified at 6 degrees before top dead center (some like 8 degrees BTDC) and then turn off the engine. Reconnect the brown timing wire.
Insert a paper clip into the Assembly Line Diagnostic Connector (ALDC), jumpering the bottom row, 2 right-most holes (A-B). Turn on the ignition, but don't start the motor. Leave everything for about 45 seconds. During this time the pintel inside the Idle Air Controller (IAC) is extending to its fullest position. The Throttle Body (TB) attaches to the front of the intake plenum runners and connects to the flexible air intake. The IAC is located under the TB on the passenger side of the motor. Disconnect the plug that connects to the IAC.
Turn off the ignition and pull the paper clip out of the ALDC. On the driver's side of the TB you'll see the screw that touches the throttle that holds the throttle plates open. The head of the screw is covered by a anti-tamper cover. Using a pointy long screw or something like that, pry out this cover, exposing the screw head (#20 torx).
Hook up your external tachometer - the one on your dash is known to be a little off, some by a couple hundred rpm. Start the engine - you might need to feather the throttle to help to get running. You're looking for about 450 rpm. Turn off the engine.
Look on the right side top of the TB, look for the 3 wires that connect to the Throttle Position Sensor (blue, black, and gray) 1 is 5 volts, 1 is ground, and 1 is a variable voltage dependent on the position of the throttle. I sliced a small piece of insulation off of each, about a 1/4 inch down from each other so there's no chance of the exposed wires touching each other. Using a digital volt meter, the top 2 wires should read .54 volts. With someone holding the throttle open all the way by hand, the voltage should read 4.65 volts.
If either of these voltages are off, you can loosen the 2 torx screws and wiggle the TPS forward or backward to affect the voltages to reach .54 and 4.65 volts. After the voltages are reached, tighten the torx screws and recheck the voltages, loosening and adjusting as necessary. Turn off the ignition.
I'd unplug the Electronic Control Mudule (ECM) - see the orange pigtail wire off the positive cable near the battery - for 30 seconds and then reconnect it. This will let the ECM re-learn for better driveability.
Hope this helps.
Engine is warmed up and the timing is verified at 6 degrees before top dead center (some like 8 degrees BTDC) and then turn off the engine. Reconnect the brown timing wire.
Insert a paper clip into the Assembly Line Diagnostic Connector (ALDC), jumpering the bottom row, 2 right-most holes (A-B). Turn on the ignition, but don't start the motor. Leave everything for about 45 seconds. During this time the pintel inside the Idle Air Controller (IAC) is extending to its fullest position. The Throttle Body (TB) attaches to the front of the intake plenum runners and connects to the flexible air intake. The IAC is located under the TB on the passenger side of the motor. Disconnect the plug that connects to the IAC.
Turn off the ignition and pull the paper clip out of the ALDC. On the driver's side of the TB you'll see the screw that touches the throttle that holds the throttle plates open. The head of the screw is covered by a anti-tamper cover. Using a pointy long screw or something like that, pry out this cover, exposing the screw head (#20 torx).
Hook up your external tachometer - the one on your dash is known to be a little off, some by a couple hundred rpm. Start the engine - you might need to feather the throttle to help to get running. You're looking for about 450 rpm. Turn off the engine.
Look on the right side top of the TB, look for the 3 wires that connect to the Throttle Position Sensor (blue, black, and gray) 1 is 5 volts, 1 is ground, and 1 is a variable voltage dependent on the position of the throttle. I sliced a small piece of insulation off of each, about a 1/4 inch down from each other so there's no chance of the exposed wires touching each other. Using a digital volt meter, the top 2 wires should read .54 volts. With someone holding the throttle open all the way by hand, the voltage should read 4.65 volts.
If either of these voltages are off, you can loosen the 2 torx screws and wiggle the TPS forward or backward to affect the voltages to reach .54 and 4.65 volts. After the voltages are reached, tighten the torx screws and recheck the voltages, loosening and adjusting as necessary. Turn off the ignition.
I'd unplug the Electronic Control Mudule (ECM) - see the orange pigtail wire off the positive cable near the battery - for 30 seconds and then reconnect it. This will let the ECM re-learn for better driveability.
Hope this helps.
