Throttle pedal sensor

[suburbanK-2500HD]

Hi

Anyone know if the sensor piece is the same on suburban and G20 van with 6,5td, for the throttle pedal.

I might have a failure in the sensor, because when in overdrive with little throttle it feels like the engine is misfiring, but i was told that its probably the sensor is not ok...

Børge

[JohnC]

A faulty TPS all set codes. Also, the failure mode is idle power only, so I think it is unlikely that is your problem.

Have you checked the codes?

[suburbanK-2500HD]

I have no codes.
The guy i talked to about this problem is Tranny specalist, he has been working with theese trannys for a long time, and has a complete overhaul shop for most trannys.

he said that the problem as i explained it to him was that the lock up function was going on\off, and he has seen this many times, and meant that its was the TPS that causes it. He did not think it was a tranny problem since it works fine when applying some more throttle. Problem is only whit light throtlle, and not increasing speed.
I recently towed my caravan, and on flat road in overdirve when accselerating its no sympthoms.
I said in my earier post its like misfiring, that is maybe wrong explained.
Its like when in overdrive you tap the brake and then in unlocks, and locks by rekeasing the brake, only in a more even pattern when it occurs.

The engine runs normal when this happens.

I have had a few times when idling and just touching the throttle pedal its like it jumps on the rpm. so its something funny going on. This occured first time about 1-1\2 2 years ago. Newer had pump codes or performance issues related to this.

The lift pump works ok.
Performance is good
Fuel consuption is normal
Dieselfilter is 1 month old

[JohnC]

You don't have that type of TPS. Yours is actually an "Accelerator Pedal Position Sensor" (APPS). The APPS is only measuring the position of the throttle pedal. It has 3 sensors. A composite output is generated by the PCM. As long as 2 of the 3 sensors agree it will work correctly. Whenever one sensor is out of bounds a code is set. No codes means no problems. The lockup signal is also generated by the PCM.

You can confirm or eliminate the APPS as the source of your problem by monitoring it with a scanner. If it reads steady while the truck acts up then it is not the issue.

Surging at light throttle settings is more likely to be caused by the injection pump or an inconsistent supply of fuel to the pump.

[suburbanK-2500HD]

You don't have that type of TPS. Yours is actually an "Accelerator Pedal Position Sensor" (APPS). The APPS is only measuring the position of the throttle pedal. It has 3 sensors. A composite output is generated by the PCM. As long as 2 of the 3 sensors agree it will work correctly. Whenever one sensor is out of bounds a code is set. No codes means no problems. The lockup signal is also generated by the PCM.

You can confirm or eliminate the APPS as the source of your problem by monitoring it with a scanner. If it reads steady while the truck acts up then it is not the issue.

I can try to test this, i have the Gmtd Scantech from Enghs motor, it shows all 3 values from the sensors


Surging at light throttle settings is more likely to be caused by the injection pump or an inconsistent supply of fuel to the pump.

Should it not behave like this in all gears if it was the IP, it only occurs in Overdrive.

.

[DmaxMaverick]

[quote=JohnC;282245]You don't have that type of TPS. Yours is actually an "Accelerator Pedal Position Sensor" (APPS). The APPS is only measuring the position of the throttle pedal. It has 3 sensors. A composite output is generated by the PCM. As long as 2 of the 3 sensors agree it will work correctly. Whenever one sensor is out of bounds a code is set. No codes means no problems. The lockup signal is also generated by the PCM.

You can confirm or eliminate the APPS as the source of your problem by monitoring it with a scanner. If it reads steady while the truck acts up then it is not the issue.
I can try to test this, i have the Gmtd Scantech from Enghs motor, it shows all 3 values from the sensors

Surging at light throttle settings is more likely to be caused by the injection pump or an inconsistent supply of fuel to the pump.
[quote]Should it not behave like this in all gears if it was the IP, it only occurs in Overdrive.

.


Fuel supply problem.

[suburbanK-2500HD]

Ok

So then will try to check the fuel pressure from the lift pump, what was the normal pressure here.

Børge

[DmaxMaverick]

4-8 PSI is normal at idle or static. Any positive pressure is all that's needed to provide sufficient fuel supply to the IP, at any speed or load. Also verify you don't have a restriction in the system, such as a plugged fuel filter, collapsed/pinched hose or line, or a failed fuel filler cap.

[suburbanK-2500HD]

Fuel filter is 1 month old, shouldnt be that(original filter)
I have about 30 litres of fuel in the tank, i can try to loosen the cap to test also.
But if it is the lift pump wont i get this kind of syphtoms at full throttle going up a hill, i have experienced that before.
Lift pump was changed august 2009(AC Delco)

[Robyn]

Two items come to mind with the symptoms you describe.

The filter harness on the optical sensor (short harness that plugs into the top of the IP and has a small black box in it) could be taking a puke.

The other possibility is small air bubbles in the fuel flow.

To check the filter harness, replace with a new one.
A bad filter harness can cause a "Fish Bite" or a feeling of a MISS

To check for air in the system, install a length of clear tubing on the return line from the IP.

Loop this line from the IP up and under a windshield wiper with a LOOP in it.

This will allow you to observe an air bubbles.

A stream of SMALL bubbles can certainly upset the IP and cause various issues.

Check these items.

94 AND 95 trucks had the filter harness, later ones did not.

This filter is supposed to stop electronic "noise" from causing issues with the injection pump operation.


Keep us posted

Missy

[TTM]

The filter harness on the optical sensor (short harness that plugs into the top of the IP and has a small black box in it) could be taking a puke.To check the filter harness, replace with a new one.
A bad filter harness can cause a "Fish Bite" or a feeling of a MISS




Is the filter harness is what is the parts name is? Or is it the optical sensor...what is the part that has to be replaced?

I'm having a very slight fish biting or stuttering on acceleration ONLY at 1100-1500rpms no other problems at any other speed or rpm level.