My car has been idling like crap for a few days now. I pulled everything off, cleaned it, and put it back together. I dont know what the problem was, but the series of things I did fixed the problem. New spark plugs, cleaned the cap and rotor contacts, new points, and cleaned and check my grounds. I set the dwell and timing and the car idles perfect now.

While I was pulling stuff out, I noticed that the spark plugs for cylinders two and three are toasty brown, and spark plugs for one and four and blacker than night. I know the injection system fires pulses to two and three and the one and four. The only thing I can think of that could cause this problem is trigger contacts. I just recently put in a new set of trigger contacts about a year ago, so I don't suspect that is the problem or at least I don't think.

The only thing that comes to mind...as you have already mentioned is the "trigger points" which account for diagonally opposed cylinder firing. They just about never fail...100,000 miles +. I know the FI injectors 1 and 3; 2 and 4 share the same ground on the cluster on the back on the engine by the transmission. Even though that isn't your problem you might check the grounds all to be good on the cluster.

Below are the contacts at the ECU...I guess you could check for continuity to the contacts on the ECU 21 and 22. You sounds like the problem lies in the trigger points. You can check them with an ohm meter.

Quoted from So, if only two injectors are firing in the pairs described, the most likely suspect is the trigger points. To replace, remove the distributor from the engine (this is the easiest way to replace the ignition points and condenser, also) and pull the trigger points out after removing the two retaining screws. You may be able to simply clean the points with a little emery paper. I use a tiny amount of distributor grease on the parts that rub on the cam. When reinstalling, note that there is some variability in the range setting of the points, try to get them near the middle of the range. You can now test them by using a voltmeter set to the ohms scale. Measure first between the middle connection and one of the outside connections. Spin the distributer shaft and you should see the points make and break connection. Now measure between the middle and the other side and repeat for the second set of points. Replace distributor and don't forget to plug in the trigger points.

1. Temp Sensor I
2. Not used
3. #1 Injector
4. #4 Injector
5. #2 Injector
6. #3 Injector
7. Pressure sensor, primary winding
8. Pressure sensor, secondary winding
9. Throttle switch (full load signal)
10. Pressure sensor, secondary winding
11. Ground, engine
12. Trigger points, common
13. Temp sensor I
14. Not used
15. Pressure sensor, primary winding
16. 12V power (from relay board)
17. Throttle switch
18. Starter motor (terminal 50)
19. Fuel pump relay
20. Throttle switch
21. Trigger points
22. Trigger points
23. Temp sensor II
24. 12V power