Surging RPM whilst driving

[boston]

Good morning everyone,

I have a 2017 3.2 Wildtrack. When Im driving the RPMs will surge for a split second and then return. I thought it might be the MAF but when I scan literally no faults. Ive looked at peddle position when driving and that looks good. I have also looked at throttle position but it seems odd to me. Below is a OSC of the readings when I Reved the engine. Slowly up to about 3.5k over 3 sec. Does this look normal to you? Video also attached of the issuie.

Thank you

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[RangerBill]

It would appear to be a bad Throttle Position Sensor as you have a calculated error appearing and feedback voltage spike.

 

[worfner]

My 2019 Ranger was surging while driving between 35-50mph, I did a little googling and found it to be the DPFE sensor. I purchased one on ebay and it took about 10-15 mins to replace. Problem solved!

 

[boston]

It would appear to be a bad Throttle Position Sensor as you have a calculated error appearing and feedback voltage spike.

Do I need the whole throttle body

 

[RangerBill]

Do I need the whole throttle body

I only have info on our North American Rangers with the 2.3L gas engines. Before changing any parts, have you checked for any DTC codes?

 

[airline tech]

I do not see a bad TPS, I see the TPS reacting normally to a (unknown) input.

The KEY is when the TP Voltage dropped - after the event, not before, it's following the PCM correction from another input (command)

1. Accelerator Position (sensors) there are 2 on the pedal - if one glitches the other sensor corrects it.

2. Possible EGR (over command) and the PCM is correcting for it

I highly suspect the - Accelerator Pedal Position Sensors (First) if you are not experiencing any other symptoms - (Buck-Surge, Misfire - Transmission Slipping)

Graph These PIDs - First

APP Sensor 1 (Voltage)
APP Sensor 2 (Voltage)
Accelerator Pedal Position D %
Accelerator Pedal Position E %

Using the (Reference Chart) for APP Voltage
KOEO - Key On Engine Off - move slowly from Released to Full Applied and note any drop-outs

Released:
APP 1 - (0.61 - 0.97) volts
APP 2 - (0.27-0.53) volts

Fully Applied
APP 1 - (3.59-4.60) volts
APP 2 - (1.72-2.40) volts

If the voltage readings (flutter or drop out) at any point while (SLOWLY) pressing the pedal - this is the root of the issue. (i would highly focus) on the pedal position where you see the RPM bump

I also suspect that if you set up the drive monitor like posted but add the APP Voltage, you may be able to see (either APP 1 or APP2) voltage flutter when the RPM's bump, it may be too quick for Forscan to see it. (Refresh Rate) of data

There are other possible factors - but for me and its quick duration points to the pedal command and what you are seeing is the PCM and the TPS reacting to that command.
Now if we were seeing a voltage drop first - followed by the TPS Relative & Error then I would say bad TPS, it comes down to what happened first.

If this proves to be - GOOD, then monitor the EGR PIDs / MAP Sensor and TCC (Slip) but my hunch is telling me to check the APP first

 

[boston]

I do not see a bad TPS, I see the TPS reacting normally to a (unknown) input.

The KEY is when the TP Voltage dropped - after the event, not before, it's following the PCM correction from another input (command)

1. Accelerator Position (sensors) there are 2 on the pedal - if one glitches the other sensor corrects it.

2. Possible EGR (over command) and the PCM is correcting for it

I highly suspect the - Accelerator Pedal Position Sensors (First) if you are not experiencing any other symptoms - (Buck-Surge, Misfire - Transmission Slipping)

Graph These PIDs - First

APP Sensor 1 (Voltage)
APP Sensor 2 (Voltage)
Accelerator Pedal Position D %
Accelerator Pedal Position E %

Using the (Reference Chart) for APP Voltage
KOEO - Key On Engine Off - move slowly from Released to Full Applied and note any drop-outs

Released:
APP 1 - (0.61 - 0.97) volts
APP 2 - (0.27-0.53) volts

Fully Applied
APP 1 - (3.59-4.60) volts
APP 2 - (1.72-2.40) volts

If the voltage readings (flutter or drop out) at any point while (SLOWLY) pressing the pedal - this is the root of the issue. (i would highly focus) on the pedal position where you see the RPM bump

I also suspect that if you set up the drive monitor like posted but add the APP Voltage, you may be able to see (either APP 1 or APP2) voltage flutter when the RPM's bump, it may be too quick for Forscan to see it. (Refresh Rate) of data

There are other possible factors - but for me and its quick duration points to the pedal command and what you are seeing is the PCM and the TPS reacting to that command.
Now if we were seeing a voltage drop first - followed by the TPS Relative & Error then I would say bad TPS, it comes down to what happened first.

If this proves to be - GOOD, then monitor the EGR PIDs / MAP Sensor and TCC (Slip) but my hunch is telling me to check the APP first

I am experiencing bucking when it's happening. I'll.graph it and post it here. I'll do it today. And thank you!

 

[boston]

My 2019 Ranger was surging while driving between 35-50mph, I did a little googling and found it to be the DPFE sensor. I purchased one on ebay and it took about 10-15 mins to replace. Problem solved!

I'll have a look too

 

[RangerBill]

I am experiencing bucking when it's happening. I'll.graph it and post it here. I'll do it today. And thank you!

Have you checked for any DTC codes?

 

[airline tech]

With the bucking symptom as well then check the following PIDs

During the event

Check

EGR Desired
EGR (Error Percentage)
EGR (Command) Duty Cycle
EGR Actual (may be noted as - Linear Lift Position - Percent)

Note how these respond when EGR is commanded

MAF - should slightly drop (smoothly)
MAP - should slightly increase

TCC Slip

Desired vs Actual

 

[airline tech]

A quick garage test - using Bi-Directional control of the EGR valve

At Idle - command the EGR valve open to 10% and note
Engine Stumble and MAF Response to help isolate clogged EGR Tube vs bad MAF reading

 

[boston]

I watched the APP and it did jump on D when it happens. However I did notice when cruise control is on it will still jump but obviously no APP as cruise is on. I then checked EGR . Have a look and see what you think. Looks to me like it's pulsing with it. I messed the recording up but still got the attached.

 

[boston]

With the bucking symptom as well then check the following PIDs

During the event

Check

EGR Desired
EGR (Error Percentage)
EGR (Command) Duty Cycle
EGR Actual (may be noted as - Linear Lift Position - Percent)

Note how these respond when EGR is commanded

MAF - should slightly drop (smoothly)
MAP - should slightly increase

TCC Slip

Desired vs Actual

Just seen this. I'll get the data from the recording.

 

[boston]

Just seen this. I'll get the data from the recording.

Here is a screenshot. It's just a short recording I messed it up. I've posted it twice so you can see what each trend line is via the key at the bottom

 

[airline tech]

From the busy overlay of data - it looks like the EGR Valve is hunting for correct position.
So:
Sticking EGR Valve (or bad position sensor-feedback)
Clogged or restricted EGR Tube - causing low flow (on MAF) and PCM is trying to adjust
Bad MAF feedback not seeing the EGR Flow


Try displaying the PIDs in a (data) vs (graph) and include the MAF response

Tighten it up with only - to get a better view of what the EGR Valve is doing

EGR Desired
EGR Command
EGR Actual
MAF
RPM

The MAF should drop (smoothly) when EGR is flowing, if it fluctuates it will cause the EGR Command to attempt to adjust the EGR valve until it sees the correct response, so this can be restricted EGR flow (tube) and the MAF reading correctly or the actual MAF - not seeing the actual flow

Summary:
From what I see - in that busy PID data is the EGR Valve is hunting for correct position and its erratic
Now it just needs to be isolated down to is it the EGR Valve sticking - slow response to movement or is it restricted EGR flow (Tube) or the MAF sensor not responding to the flow.

EGR Desired should remain stable until commanded to change
EGR Command - adjusts to EGR Desired, then fine tunes the command from the actual flow response (MAF)
In a normal operation - the EGR Command and the Actual should match (closely)


NOTE:
I cannot see the manuals for the 3.2 variant - from what I can tell, the 3.2 does not have the DPFE sensor (used for EGR Flow) the same as the 2.3 does - the 3.2 uses the MAF instead.
However, there is a DFE sensor that is used for the particulate filter, and this creates conflicting information due to the close naming of the 2 sensors, so if I am correct here you do not have a DPFE and the MAF is providing the feedback the same way the DPFE does for the 2.3 engine.

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