midmofarmer

obd reads 21, 24, 10 ,18 so i'm lost idles rough also, new plugs and wires and new fuel filters

what is 21 X X X ECT out of self test range 0.3 to 3.7 volts. ?

temerature sensor? whers it at on a 302

GhostriderI

Codes

21
Engine Coolant Temperature Higher Or Lower Than Expected

24
Intake Air Temperature Higher Or Lower Than Expected

10
Cylinder 1 Contribution Or Balance Malfunction

18
Loss Of Ignition Diagnostic Monitor Input To Power train Control Module SLASH Spark Output Circuit Grounded

Source: https://actron.com/code-lookup

Hope this helps

klricks

You can get a false 21 and 24 if you attempt to run the diagnostics / code read on a cold engine.
10 is not a code. It is a separator digit between the KOEO codes and the CM codes.
The KOEO codes are generated at the time the tests are performed. The CM codes are codes stored in memory and are from faults that happened in the past during normal recent operation of the vehicle.

The same code number can have different meaning depending on if KOEO or CM.
Also codes can have different meanings if from car or truck or different engines.

For detailed information on the diagnostic tests see the OBD1 write-up in my web page.

Also this is a good code reference: http://equus.com/Content/Support/Man..._20NOV2002.pdf