Help Needed Guess what? Replacing the CPS didn't help!

[CHPMustang]

Just so I'm not making expensive recommendations that aren't the real answer, just a few clarifications on what it's doing.

1)We do not have "emissions system" lights on US trucks so I'm hoping and guessing that this is roughly equivalent to our Check Engine light unless they were required to install additional emissions equipment to meet your local emissions standards as US standard trucks have no computer controlled or monitored emissions equipment.
2) When the truck acts up does the engine die and need to be restarted? or just kick to idle?

If it is kicking to idle and/or giving less fuel than "normal" for throttle position then I would suspect the electronic pedal assembly. They are a couple hundred dollar part and fail somewhat regularly. An errant reading from the throttle position sensor and idle validation switch (one piece on SD trucks) will trigger a computer fault.

When a CPS fails the engine will go dead requiring you to turn the key to restart the engine.

I have had 7.3L trucks not restart and some that did but the engine ends up shutting off cold turkey not much longer afterwards

 

[BJS]

. The engine is in idle as the truck is decelerating and there is no response whatsoever from the throttle.

I have had 7.3L trucks not restart and some that did but the engine ends up shutting off cold turkey not much longer afterwards

exactly my point when the CPS fails the engine shuts off and is no longer idling or running at all.

His description leads me to believe that the engine is running but no throttle response and the PCM is providing fuel to idle and no more.

 

[Friis]

1)We do not have "emissions system" lights on US trucks so I'm hoping and guessing that this is roughly equivalent to our Check Engine light unless they were required to install additional emissions equipment to meet your local emissions standards as US standard trucks have no computer controlled or monitored emissions equipment.

I don't think there are any special systems on my truck. The owners manual says that this light is called emission system, but I would suspect it is the check engine light. It's the light above the arrow in the attached picture.

2) When the truck acts up does the engine die and need to be restarted? or just kick to idle?

It kicks to idle. Never dies. And usually after a few seconds (and a few presses on the gas pedal) the throttle is back.

If it is kicking to idle and/or giving less fuel than "normal" for throttle position then I would suspect the electronic pedal assembly. They are a couple hundred dollar part and fail somewhat regularly. An errant reading from the throttle position sensor and idle validation switch (one piece on SD trucks) will trigger a computer fault.

This seems likely. Would this show up as an error code if scanned?

 

[JLDickmon]

This seems likely. Would this show up as an error code if scanned?

not necessarily.

in the picture you posted, it looks like all the prove-out's are working.. all this is, is a bulb check.

illuminated like it is now does not mean a problem.

once the truck is started, the rest of the lights cycle off,
if it stays on, YES there is a problem detected and a fault code stored.

 

[iracemine]

I like the chip idea, but don't minimize the battery connections. and then I could also throw in the idea of pedal assembly going bad.

 

[Friis]

not necessarily.

in the picture you posted, it looks like all the prove-out's are working.. all this is, is a bulb check.

illuminated like it is now does not mean a problem.

once the truck is started, the rest of the lights cycle off,
if it stays on, YES there is a problem detected and a fault code stored.

I know, I just took this pic to show which light I was talking about. It doesn't stay on. It lights up at random while driving, followed by the symptoms I described below.

 

[BJS]

I don't think there are any special systems on my truck. The owners manual says that this light is called emission system, but I would suspect it is the check engine light. It's the light above the arrow in the attached picture.



It kicks to idle. Never dies. And usually after a few seconds (and a few presses on the gas pedal) the throttle is back.



This seems likely. Would this show up as an error code if scanned?

the light is the standard CEL (check engine light) or SES (service engine soon) light that is on US trucks and is triggered by a computer sensed failure.
Kicking to idle but not dying is one of the most common symptoms of the pedal assembly failing. The pedal assembly on the SD is a combination that includes a potentiometer to determine how far you're pressing the pedal and an idle validation switch that is engaged when the throttle is released tells the computer to ignore the signal from the potentiometer. the IVS portion does not fail too frequently but the potentiometers often will develop dead spots so the computer receives a signal outside of the normal voltage range and it throws an error and the engine reverts to idle speed. Often a short term fix while driving is to rapidly fully cycle the pedal from idle to full throttle. These are not exactly cheap and there are some mid year breaks in the part numbers so you may need to have your build date handy when ordering.

It should show an error P0221 If memory serves me right when scanned however I can say that my brother's '01 never stored a code when his was on the fritz.

 

[Friis]

the light is the standard CEL (check engine light) or SES (service engine soon) light that is on US trucks and is triggered by a computer sensed failure.
Kicking to idle but not dying is one of the most common symptoms of the pedal assembly failing. The pedal assembly on the SD is a combination that includes a potentiometer to determine how far you're pressing the pedal and an idle validation switch that is engaged when the throttle is released tells the computer to ignore the signal from the potentiometer. the IVS portion does not fail too frequently but the potentiometers often will develop dead spots so the computer receives a signal outside of the normal voltage range and it throws an error and the engine reverts to idle speed. Often a short term fix while driving is to rapidly fully cycle the pedal from idle to full throttle. These are not exactly cheap and there are some mid year breaks in the part numbers so you may need to have your build date handy when ordering.

It should show an error P0221 If memory serves me right when scanned however I can say that my brother's '01 never stored a code when his was on the fritz.

Thanks. I'm almost sure that's the problem then. Especially since I've had the problem for years, and it always disappears after restarting the vehicle.

Would this be the part in question? Car Part Wholesale - Auto Parts and Accessories Catalog - Dorman Accelerator Pedal Position Sensor

 

[BJS]

that looks like the right part, double check your truck to ensure that the TPS can be removed. Some they can't and you're in for a full pedal assembly.