88 3FE w code 41 ( throttle position sensor) (1 Viewer)

[gjolli1]

Trying to figure this out and we have it a wall. Vehicle symptoms are randomly cutting out and occasionally dying at a stop light. We have no voltage between ECU terminals (w key on) VTA & E2 (checked at ECU) - Replaced ECU but no change
E2 ground test good. Replaced new OEM TPS (adjusted) New OEM air meter, new oxy sensor, and new fuel injectors. Also, there is no change between on either TPS or air meter when opened or closed.

See the below attachments with notes on the results. Any help would be greatly appreciated!

Greg

 

[toy_tek]

How are you checking the wiring between the ECU and TPS?

 

[gjolli1]

How are you checking the wiring between the ECU and TPS?

We are following the steps in the attached manual, all of them. I appreciate your interest and feedback. Thank you

 

[Engineer8000]

The VTA wiper picks a voltage off the TPS potentiometer (pot) depending on throttle position. Since you have 5V across VC and E2, the voltage from VTA to E2 will vary between 5V and some lower number as the wiper approaches the E2 end of the pot (E2 is GND). Since your VTA voltage at the ECU is not changing with throttle position, there is a problem with the wiring between the ECU and TPS, or maybe the TPS is not properly engaging with the throttle body? The fact you have 4v on VTA at the ECU and 5v from IDL to E2 off idle sort of rules out a wiring problem. Check IDL to E2 with throttle valve closed to be sure E2 wiring is good (should be 0 v).


The VC-E2 voltage should not change with throttle position.

When measuring VS-E22, are you moving the plate in the AFM? The AFM VS wiper works like the VTA pot wiper in the TPS. VC to E22 is 5V so the voltage from VS to E22 at the ECU should vary from around 5v to nearly 0V as the plate in the AFM moves, and the wiper nears the E2 end of the pot.

Good luck, I know these can be frustrating.

Electronics Basics - How a Potentiometer Works | Random Nerd Tutorials

A potentiometer may come in a wide variety of shapes and are used in many applications in your daily life, for example to control the audio volume of the radio

randomnerdtutorials.com

 

[gjolli1]

Thank you for your pointers. These are the results below

Measured at the ECU key on

VTA-E2 Throttle open - OV
VTA-E2 Throttle closed- OV
IDl-E2 Throttle Closed- OV
VC-E2 Throttle open - 5V
VC-E2 Throttle closed - 5V
VS-E22 Air Meter Open - 0V
VS- E22 Air Meter closed - 0V

 

[Engineer8000]

Your initial post had VTA-E2 at 3.97V both open and closed, now it is 0?

 

[gjolli1]

Not sure, maybe we screwed up on the first the first time. After reading your response/question we re tested. It’s definitely 0

W key on
VTA- E2 ---0 volts at ECU and at TPS .
Throttle open and Throttle closed
Also Getting continuity on both wires. Tried this w both ecu’s for identical results