Gentleman. I have a 1992 F-150 with a 5.0 auto trans.
Engine surges during low speed.
Pulled codes
KOEO
127
327
328

KOER
121
311

I plan on cleaning throttle body and EGR.
But what does code 311 mean "Thermactor air system/fault during engine run self test.

Thx in advance

 

You might not have three digit codes as there is not a code 127.

But if you do and they are as stated and no CM codes then:

DTC 121 indicates the Throttle Position (TP) sensor rotational setting may be out of Self-Test range.
Possible causes:
-- Binding throttle linkage.
-- TP sensor may not be seated properly (tightened down).
-- Damaged TP sensor.
-- Damaged Powertrain Control Module (PCM).

DTCs 311 indicate the Secondary Air Injection system is inoperative.

Possible causes:
-- Vacuum hoses damaged.
-- AIRB/AIRD valve inoperative.
-- Air Pump inoperative.
-- AIRB/AIRD solenoids damaged.

DTC 327 indicates the EGR Valve Position (EVP) sensor signal is less than the Self-Test minimum value of 0.2 volt.
NOTE:
Because the EVP sensor is preloaded when attached to the EGR valve, a failure in the EGR valve causing the EVP sensor to lose preload may also set DTC 327.

Possible causes:
-- Damaged EVP sensor.
-- Damaged EGR valve.
-- Open harness.
-- Grounded harness.
-- Damaged Powertrain Control Module (PCM).

DTC 328 in Key On Engine Off (KOEO) and Key On Engine Running (KOER) indicates the EGR valve and/or EVP sensor voltage is lower than normal in the closed position. The EVP voltage is less than the closed limit voltage of 0.24 volts. Because of the preload of the EVP sensor, it is difficult to determine whether the EGR valve has malfunctioned or the EVP sensor has an abnormally high resistance.

Possible causes:
-- Poor continuity in EVP sensor harness or connectors.
-- Damaged EGR valve.
-- Damaged EVP sensor.
-- Damaged Powertrain Control Module (PCM).

 

Thank You suibford.
My type O. The code is 121 not 127
Do you thing testing the EGR wit vacum will eliminate that code if sticking? I dont have the knowledge you have and rely on tis forum for some elp.

 

DTC 121 indicates the Throttle Position (TP) sensor's rotational setting may be out of Self-Test range.

Possible causes:
-- Binding throttle linkage.
-- TP sensor may not be seated properly (tightened down).
-- Damaged TP sensor.
-- Damaged Powertrain Control Module (PCM).

 

I would check voltage as you may not have a good 5 volt reference voltage.
You might start by opening up the PCM Computer and checking the caps. I think you may find you have some leaky ones.

 

Tanks again subford. I will check all this weekend weater permiting.