when i start my truck it idles fine but when i put it in reverse and give it a little gas it shudders and almost stalls. it will also shudders in drive too. it will do this sometimes and then sometimes it doesn't. the truck is a 5.8 automatic and i have replaced the map sensor. it doesnt spit any codes when i hook it up to a reader. please help

 

Sounds like a bad TPS but you need to run the self-test to check for any codes. Both the KOER and see if any codes are stored in CM. If it is a TPS it will show up in the KOER part of the self-test.

 

how do i run the self test

 

Assuming you do not have a California truck (OBD-II).

The easy way is to buy a code reader for about $20-$30.
The one to get is the Equus 3145:


You can get it at most auto part stores or on amazon.

The hard way is to ground the STI (Self Test In) wire and get behind the wheel with paper and pin or a video camera, turn on the key and count the flashes the MIL in your cluster flashes out.

It will output the KOEO electrical test first and then a space code of one flash and then the CM stored codes will flash out.
If you get the all clear for the KOEO (111, 111) and then the space (1) and then the CM of 111, 111 then you can run the KOER actuator self-test to check the response of the actuators and their paired up sensors.

To run the KOER self-test ground the STI wire and start the engine. You will need to goose it once push on the brake once and push the OD button during the test.

 

More info on doing a self-test AKA quick-Test:

Special Notes:
The Key On Engine Off and Key On Engine Running Self-Tests detect faults that are present at the time of testing. Faults that occur only when the vehicle is operating or intermittent faults that have occurred in the last 80 warm-up cycles are detected during Continuous Memory Self-Test, stored in Continuous Memory and displayed during Key On Engine Off Self-Test.

When directed to a Pinpoint Test, always read the cover page(s) for special notes and look carefully at the Pinpoint Test Schematic.

After service, rerun Quick Test to ensure that service was effective.

It may be necessary to disconnect or disassemble harness connector assemblies to do some of the inspections. Pin locations should be noted before disassembly.

Visual Check

1. Inspect the air cleaner and inlet ducting.
2. Check all engine vacuum hoses for damage, leaks, cracks, blockage, proper routing, etc.
3. Check EEC system wiring harness for proper connections, bent or broken pins, corrosion, loose wires, proper routing, etc.
4. Check the Powertrain Control Module (PCM), sensors and actuators for physical damage.
5. Check the engine coolant for proper level and mixture.
6. Check the transmission fluid level and quality.

Make all necessary repairs before continuing with QUICK TEST.

Vehicle Preparation
1. Perform ALL safety steps required to start and run vehicle tests - apply parking brake, put shift lever firmly in PARK position (NEUTRAL on manual transmission), block drive wheels, etc.
2. Turn off ALL electrical loads--radios, lights, A/C, heater, blower, fans, etc.

Using the Malfunction Indicator Lamp (MIL)

No special equipment hookup is required. STI is jumpered to SIG RTN at Self-Test Input (STI) connector and the Data Link Connector (DLC).

Key On Engine Off Self-Test

Special Notes:
Continuous Memory Diagnostic Trouble Codes (DTCs) recorded in this step will be used for diagnosis after a PASS code 111 is received in both the Key On Engine Off and the Engine Running Self-Tests.
Deviation from this procedure may cause the output of false DTCs.

How To Run The Key On Engine Off Self-Test
DO
Verify that the vehicle has been properly prepared.
Start engine and run until it reaches normal operating temperature.
Turn engine off and wait 10 seconds.
Activate Self-Test.

Jumper STI to SIG RTN at the DLC and STI connectors. DTCs will be flashed on the Malfunction Indicator Lamp (MIL).

Place ignition key in the ON position.
Record all Diagnostic Trouble Codes (DTCs) displayed.

DON'T
Depress throttle during Key On Engine Off Self-Test.

Key On Engine Running Self-Test

Special Notes:
On vehicles equipped with the Brake On/Off (BOO) circuit, the brake pedal MUST be depressed and released AFTER the ID code.

On vehicles equipped with electronic overdrive transmission, the Transmission Control Switch (TCS) must be cycled after the ID code.

The Dynamic Response code is a single pulse (or a 10 code on the Super Star II Tester) that occurs 6-20 seconds after the engine running identification code. (See Code Output Format in this section.)

When/if the Dynamic Response code occurs, perform a brief wide open throttle.

How To Run Key On Engine Running Self-Test

DO
Deactivate Self-Test.
Start and run engine until it reaches normal operating temperature.
Turn engine off, wait 10 seconds.
Activate Self-Test.
Start engine.
After the ID code, depress and release the brake pedal if appropriate. See Special Notes above.
If a Dynamic Response Code occurs, perform a brief wide-open throttle (WOT).
Record all Diagnostic Trouble Codes (DTCs) displayed.

DON'T
Depress the throttle unless a Dynamic Response code is displayed.

Self-Test Description

The Self-Test is divided into three specialized tests: Key On Engine Off Self-Test, Key On Engine Running Self-Test, and Continuous Memory Self-Test. The Self-Test is not a conclusive test by itself, but is used as a part of the functional Quick-Test diagnostic procedure. The PCM stores the Self-Test program in permanent memory. When activated, Self-Test checks the EEC system by testing memory integrity and processing capability, and verifies that various sensors and actuators are connected and operating properly.

The Key On Engine Off and Key On Engine Running Self-Tests are functional tests which only detect faults present at the time of the Self-Test. Continuous Memory Self-Test is performed during normal vehicle operation and stores any fault information in Keep Alive Memory (KAM) for retrieval at a later time.

Key On Engine Off Self-Test

At this time, a test of the EEC system is conducted with power applied and engine at rest.

To detect errors during Key On Engine Off Self-Test, the fault must be present at the time of testing.


Separator Pulse

A single 1/2 second separator pulse is issued 6-9 seconds after the last Key On Engine Off DTC. Then, 6-9 seconds after the single 1/2 second separator pulse, the Continuous Memory DTCs will be issued.


Continuous Memory Diagnostic Trouble Codes (DTCs)

Continuous Memory DTCs are issued as a result of information stored during Continuous Memory Self-Test, while the vehicle was in normal operation. These DTCs are displayed only during Key On Engine Off Self-Test and after the separator pulse. Intermittent faults that have not occurred in the last 80 warm-up cycles (40 cycles on some applications) are erased from Continuous Memory and will not produce a Continuous Memory DTC.

NOTE:
The separator pulse and Continuous Memory DTCs follow Key On Engine Off DTCs ONLY.


Key On Engine Running Self-Test

At this time, a test of the EEC system is conducted with the engine running. The sensors are checked under actual operating conditions and at normal operating temperatures. The actuators are exercised and checked for expected results.


Engine Identification Codes (ID Codes)

Engine ID codes are issued at the beginning of Key On Engine Running Self-Test and are one-digit numbers represented by the number of pulses sent out. For gasoline engines, the engine ID code is equal to one-half the number of engine cylinders (i.e. 4 pulses = 8 cylinders). These codes are used to verify the proper PCM is installed and that the Self-Test has been entered.

Dynamic Response Check

The dynamic response check is used on some applications to verify operation of the TP, MAF, MAP and KS sensors during the brief Wide-Open Throttle (WOT) performed during the Key On Engine Running Self-Test. The signal for the operator to perform the brief WOT is a single pulse or 10 code.


Brake On/Off Test

On vehicles equipped with Brake On/Off (BOO) input, the brake pedal MUST be depressed and released AFTER the ID Code has been displayed. This tests the ability of the EEC system to detect a change of state in the Brakelamp Switch.


Transmission Control Switch (TCS) Test

On vehicles equipped with TCS, the switch must be cycled after the ID code has been displayed. This tests the ability of the EEC system to detect a change of state in the TCS.


Adaptive Fuel Self-Test

Adaptive fuel logic is used in fuel injection systems primarily to account for normal variability in fuel system components. When the fuel system is detected to be biased rich or lean during steady state vehicle operation, Adaptive Fuel will make a corresponding shift in the fuel delivery calculations so an unbiased condition will exist. The adaptive fuel "shift" is stored in Keep Alive Memory (KAM), which is powered by the vehicle battery. This prevents Adaptive Fuel from being lost when the vehicle is turned off.


Code Output Format

The EEC system communicates service information through the Diagnostic Trouble Codes (DTCs). These DTCs are three-digit numbers representing the results of Self-Test.

The DTCs are transmitted on the Self-Test Output (STO) circuit found in the Data Link Connector (DLC). They are in the form of timed pulses, and are read by the technician on a voltmeter, SUPER STAR II tester or Malfunction Indicator Lamp (MIL)



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Thank for the info