I just finished the engine swap in my 84 TA and it is idling terrible. I have no codes in the system and the dwell is stuck at 9 degrees at idle. I have a new O2 sensor, and CTS too. I dont know what could be causing it, unless maybe I have a vacuum leak that im overlooking. I wont idle on its own when its warm. It runs OK when you first start it up when its cold, but as it warms up it starts running worse and worse and I have to keep my foot on thegas to keep it idling. Part throttle is fine. Anyway, what are some other things to check here. The only thing I can think is a vacuum leak, but I cant seem to find one. BTW, the MCS does click when I turn the key on.

 

You may need to bring the idle mixture screws into the adjustment process.

 

Check temp sensor-ecm may think it's not warmed up yet and check throttle position sensor-ecm may think it's at full-throttle.

Assuming you've already checked your timing.

 

Wouldnt it throw a code if the CTS was bad??

 

Sounds like it's trying to run full rich. Does the dwell vary as you open the throttle? If so your sensors are probably good but your idle mixture is likely off. This is most likely if the system was working properly before the swap. Five7 usually gives good advice.

Could also mean your o2 sensor isn't warm enough at idle for a good reading and the ecm stays closed. If you swapped from the cast iron exhaust, a switch to a heated o2 sensor is an option.

The system's really basic and will only throw codes when the ecm sees parameters that are way out of whack. The sensors are easy to check with a voltmeter if the above didn't apply.

 

The dwell does change as the throttle is opened.....

 

Check your idle mixture screws, start at four turns out on each. Make sure it's warmed up and you can adjust these until you start seeing some dwell at idle. Then you can adjust your idle air mixture screw until you're at 30 degrees.

If your o2 sensor's not hot enough at idle you can swap in a heated o2 sensor. Shouldn't be a problem if you're still running the cast iron exhaust.

 

Ill have to check the mixture screws. Gonna be a chore though...the factory plugs are still there....

 

If the factory plugs are still there, I'd check everything else first. Sounds like it's running too lean at idle-when it's cold it runs fine cause the choke richens the mixture. Was this carb running good before the swap? Could it be an issue with the float level, lean or rich stop adjustment, etc? When you unplug the tps does it run different/better? Is it idling low-then dying? Can you bump up the idle speed to keep it running? How much adjustment did you try with the idle air mixture screw? There's alot to check.