82 Crossfire Choke/Idle Issue
Thread Starter
Le Mans Master
Joined: Feb 2000
Posts: 7,032
Likes: 2
From: Newburgh NY
82 Crossfire Choke/Idle Issue
A friend has an 82 with the problem he described below. Anyone familiar with setting a Crossfire up for cold/warm start and choke/idle operation? I can do the work, just wanted to know which direction to head in to sort it out. Thanks
"Here's the background. The car was tuned with new wire set by the local garage that services it. After a while it appeared to be running on fewer than 8 cylinders when cold. I brought it back and the diagnosis was the computer and oxygen sensor needed replacement, which was done.
Then the cold idle problem began. When I brought it in again, he raised
the idle speed, which took care of the cold idle, but left me fighting
brake against engine the rest of the time. The car could maintain 35 mph on a level road with no gas being applied. So I asked him to lower the idle and now have to use the gas pedal to keep it running from a cold start until it warms up a little."
"Here's the background. The car was tuned with new wire set by the local garage that services it. After a while it appeared to be running on fewer than 8 cylinders when cold. I brought it back and the diagnosis was the computer and oxygen sensor needed replacement, which was done.
Then the cold idle problem began. When I brought it in again, he raised
the idle speed, which took care of the cold idle, but left me fighting
brake against engine the rest of the time. The car could maintain 35 mph on a level road with no gas being applied. So I asked him to lower the idle and now have to use the gas pedal to keep it running from a cold start until it warms up a little."
Race Director
Joined: Dec 1999
Posts: 16,945
Likes: 9
Sounds like he just messed with the throttle plates a bit, did he use a manometer to synchronise both sides?
You'll need a manometer or inches of water gauge, a dremel tool, and a drill.
First drive car until operating temperature is reached.
Ground the diagnostics terminal (closing IAC's, they cycle in and out, remove iac connector when iac's cycle out, repeat untill fully seated) and disconnect both IAC connectors.
You can also use special plugs or a duct tape to plug the IAC (kidney shaped) holes on the TB's. The best would be to do both.
Pop out plug on rear throttle Body by drilling a hole at an angle behind it, then poking something in it to pop it out.
There is another way to remove the plugs without damaging the throttle bodies.
Remove the square vacuum fitting behind the rear Throttle Body for clearane, the front TB's plug can be reached easily.
Use a small drill to makel a hole in the caps and use a small screwdriver and a fulcrum to pop them out.
It maybe a little harder than the other method but it'll keep your Throttle Bodies undamaged.
Break the weld on the balance screw so it can be adjusted.
Set the balance screw so that it doesn't interfere with the setting of both plates (this is the pos. where the plates are angled the same and there's the elast sideways friction in the link)
Put the water manometer on the center port of the rear Throttle Body.
Set the vacuum with idle stop screw to 6 inches of water.
Cap the rear Throttle Body port.
Put the gauge on front Throttle Body center port.
Adjust the BALANCE/SYNCHRO screw to get 6 inches of water.
Cap all open ports when done.
If you don't have a manometer there is a method to get acceptable minimum air settings. Use this for emergency and have the minimum air set correctly later. Turn both Throttle stop screws until the screw is loose from the linkage. Then turn the balance srew so that both throttle valves are in the same position (fully closed) This position can be found as the position where the linkage connection rod can be moved side to side with the least resistance. Then turn the rear stop screw 1/2 a turn and the front 3/4 of a turn.
Here you can see the rear TB's throttle stop screw:
Here is the original balance screw:
And here's a "new" screw in it's place:
It is NOT recommended to replace the original screw with another one like this. The original screw (when the weld is broken) is much more convenient to adjust that this one. The original screw can be turned by hand easily.
When doing the balancing with a manometer this is how you "read" it:
Figure 2.1 is the situation with no vacuum on the manometer, Fig. 2.2 is not relevant, Fig. 2.3. shows the height h wich must be 6" of water or 0,45" Hg when using a mercury manometer. Here you can see that using the water type manometer will result in a more accurate setting. .
After setting minimum air the Throttle Position Sensor needs to be readjusted. to 0,525V at closed throttle.
You'll need a manometer or inches of water gauge, a dremel tool, and a drill.
First drive car until operating temperature is reached.
Ground the diagnostics terminal (closing IAC's, they cycle in and out, remove iac connector when iac's cycle out, repeat untill fully seated) and disconnect both IAC connectors.
You can also use special plugs or a duct tape to plug the IAC (kidney shaped) holes on the TB's. The best would be to do both.
Pop out plug on rear throttle Body by drilling a hole at an angle behind it, then poking something in it to pop it out.
There is another way to remove the plugs without damaging the throttle bodies.
Remove the square vacuum fitting behind the rear Throttle Body for clearane, the front TB's plug can be reached easily.
Use a small drill to makel a hole in the caps and use a small screwdriver and a fulcrum to pop them out.
It maybe a little harder than the other method but it'll keep your Throttle Bodies undamaged.
Break the weld on the balance screw so it can be adjusted.
Set the balance screw so that it doesn't interfere with the setting of both plates (this is the pos. where the plates are angled the same and there's the elast sideways friction in the link)
Put the water manometer on the center port of the rear Throttle Body.
Set the vacuum with idle stop screw to 6 inches of water.
Cap the rear Throttle Body port.
Put the gauge on front Throttle Body center port.
Adjust the BALANCE/SYNCHRO screw to get 6 inches of water.
Cap all open ports when done.
If you don't have a manometer there is a method to get acceptable minimum air settings. Use this for emergency and have the minimum air set correctly later. Turn both Throttle stop screws until the screw is loose from the linkage. Then turn the balance srew so that both throttle valves are in the same position (fully closed) This position can be found as the position where the linkage connection rod can be moved side to side with the least resistance. Then turn the rear stop screw 1/2 a turn and the front 3/4 of a turn.
Here you can see the rear TB's throttle stop screw:
Here is the original balance screw:
And here's a "new" screw in it's place:
It is NOT recommended to replace the original screw with another one like this. The original screw (when the weld is broken) is much more convenient to adjust that this one. The original screw can be turned by hand easily.
When doing the balancing with a manometer this is how you "read" it:
Figure 2.1 is the situation with no vacuum on the manometer, Fig. 2.2 is not relevant, Fig. 2.3. shows the height h wich must be 6" of water or 0,45" Hg when using a mercury manometer. Here you can see that using the water type manometer will result in a more accurate setting. .
After setting minimum air the Throttle Position Sensor needs to be readjusted. to 0,525V at closed throttle.
Melting Slicks
Joined: Jun 2001
Posts: 2,340
Likes: 2
From: Moro IL
Along with what twinturbo said, I'm not real familiar with the crossfire setup since it was a very short lived intake design, but I've run across similiar problems with GM's E4ME intakes when the heat crossover would become clogged with carbon causing cold driveability problems that would clear up once warmed. Not sure if the crossfire intake uses such a passage but I thought I'd toss it up as a possibility.
Pat Kunz
Pat Kunz
