HELP BOYS AND GIRLS
THE CAR RUNS ROUGH AT IDLE OVER 700 RPM CAR RUNS LIKE A NEW ONE. THIS IS A CROSSFIRE CAR I HAVE FOUND AND FIXED ALL VACUM LEAKS. " IAC" MOTORS TAKEN OUT AND CLEANED TIGHTENED ALL PLENTUM BOLTS . THE CAR WAS STORED IN A GARAGE FOR SIX YEARS HAD TO PUT NEW FUEL PUMP AND FUEL FILTER IN CAR ALSO NEW INJECTORS .

MARK 82

Hi Mark 82,
My crossfire also idles rough. I did everything you did plus had the intake manifold gasket replaced(they usually leak), the throttle position sensor changed and I needed a new ECM. Also, did all the standard tune up things like plugs and wires. Are you showing any check engine light? I'm sorry I don't have an answer for you, but I'm starting to think I'm just going to have to live with the rough idle.
Good luck,
Tom

Crossfires are not bad to cure. When everything else is right, you need to balance the two units or it won't idle properly.

To do this, block off the IAC ports, so the car is running at base idle. There are special plugs to do this, but can be done without the tools. Make sure there are no leaks, or you will be wasting your time, and maybe making it worse. Look up the base idle specs. Now you need a very sensitive gauge. A water manometer works best. There is a port at the top of each throttle body assembly. Connect your very touchy gauge or manometer to these ports. Again, the manometer can be connected to both at the same time, which makes it easier.

Now adjust the throttle plate stop screw on one or the other TBI (throttle body) to get equal vacuum readings. This is a VERY TOUCHY adjustment. A standard vacuum gauge is no where near good enough. It won't even get you close. When you have the same vacuum, and the base idle is correct, the throttle bodies are balanced. It makes a huge difference in idle quality.

Don't have a touchy exact gauge or manometer? Make your own manometer. Just get about 4 feet of clear vinyl hose, the same size as your vacuum ports. Tape it to a yardstick, broom handle, etc. Put the center of your hose at the bottom and make a U shape going up. When you have about a foot high U shape, put a bit of water in the hose so it fills about 1/2 of the way up your hose U. Now connect the loose ends to your vacuum ports. You have a manometer. When the water level is balanced and at equal level on both sides of the U, the throttle bodies are balanced. A drop of food color in the water makes it much easier to see and read.

Make sure you had the IAC ports blocked, and set the minimum idle speed to specs.

If they are way off, you may suck the water out of one side. Don't worry it won't hurt anything. It might stall. Just restart.

The side with the higher water level has the greater vacuum. To increase vacuum, turn the screws to open the throttle plate a bit. To lessen vacuum, back off the screw to close the plate a bit.

You may find the throttle plate adjustment screws are under seals. You may have to drill out or cut away seals to adjust the screws. Be careful you don't damage the screws or surrounding area.

The second time you do this it's a piece of cake.