Service Electronic Throttle Control and the Rabbit Hole

[Ram_Okie]

Hello everyone. I am a new owner of a 2019 Ram Limited 5.7 Hemi without eTorque. When I bought this truck it had some minor issues and I have been working through them. I tripped a P2173 code which made me start down the path of looking at the ETC. During that time I found out I had cracked exhaust manifolds and had those replaced. I was hoping that was the result of my lean issues but I have received that check engine twice since then. I was looking at another thread here were people were pulling Fuse 53 to reset the module. That helped clear the CEL but I have since bought a OBD2 reader and have started trouble shooting other related components. I found my throttle pedal sensor might be acting up. I plotted ACC Pedal D and ACC pedal E on my reader and pedal E has some drop out. Has anyone else noticed this?

 

[Ram_Okie]

After doing some research pedal E is pulled to ground as part of a ground fault test on the PCM. Back to trying to figure out my issue. When researching the P2173 that it throws intermittently; it looks like that is labeled: Powertrain Control Module (PCM) - High Airflow/Vacuum Leak Detected (Slow Accumulation). So maybe PCV valve or vacuum leaks. I would think if it was a hard failure that it wouldn't go away and then come back. This is a difficult one.

 

[Cbty2050]

I will attach a few documents. Out of the two attachments, I have seen multiple camshaft pin failures. Good luck.

 

[kapinallinen2]

Pin failure, no good.
Lets hope for a good old vacuum leak.

P2173-HIGH AIRFLOW/VACUUM LEAK DETECTED (SLOW ACCUMULATION)

Theory of Operation

The Powertrain Control Module (PCM) uses the Manifold Absolute Pressure (MAP) Sensor base model and the Electronic Throttle Control (ETC) Motor position value to create a calculated MAP model value. This calculated MAP model is then compared to the actual MAP Sensor Signal input to the PCM. The PCM uses this comparison to detect vacuum leaks or restrictions in the intake air system. The purpose of this monitor is to detect an instantaneous or gradual change in the intake manifold vacuum that exceeds the calibrated high or low thresholds.

NOTE: Do not use shop air to clean out the MAP Sensor when diagnosing a MAP Sensor related fault as this will cause internal damage to the sensor.

When Monitored and Set Conditions

When Monitored: This diagnostic runs when the following conditions are met:

With the engine running.

Engine speed above approximately 285 rpm.

No active MAP Sensor, Throttle Position Sensor, CMP/CKP Sensor or 5-Volt Reference DTCs.

P2172 or P2174 are not present.


Set Conditions:

The Powertrain Control Module (PCM) monitors and compares the difference between the actual Map Sensor reading and the calculated Map Sensor model over time. The PCM detects a gradual long term increase in the difference between these two values, beyond a calibrated adaptive limit, indicating that there is an air leak in the intake system.

Default Actions:

The MIL will illuminate.

The ETC light is enabled.


Possible Causes

VACUUM LEAK

PCV VALVE OR HOSE LEAKING OR RESTRICTED

RESTRICTION IN THE EXHAUST SYSTEM

INTERNAL ENGINE MECHANICAL COMPONENTS

RESISTANCE IN THE 5-VOLT SUPPLY CIRCUIT

RESISTANCE IN THE MAP SIGNAL CIRCUIT

RESISTANCE IN THE MAP SENSOR GROUND CIRCUIT

MAP SENSOR

THROTTLE BODY - OBSTRUCTION OR FOREIGN OBJECT/MATERIAL

POWERTRAIN CONTROL MODULE (PCM)

 

[Cbty2050]

Lets hope for a good old vacuum leak.

Not a known issue of vacuum leaks. If so that would be an easier fix.

 

[Ram_Okie]

So the weird thing is it only happens every so often (Maybe once a month). I'll drive all the way to work and it trips after I get into a parking spot and shift into park. I would think a vacuum leak would cause me to have this more often and not so sporadic. I'll check all the vacuum hoses just to be sure. When I plugged in the reader it said replace throttle body as the recommended repair.

 

[jonnygobig]

Cool string, possibly related to other reported shifts to neutral and park at slow speed intermittently. This string gets intense fast but the quickest free checks might help, Throttle body clean has fixed the quasi low speed stall, my guess is it plays into this code as well, before you clean it, exercise by hand and you can feel some sticky right at fully closed. Breakaway stiction could cause software to see upper or lower control limits momentarily. I cleaned and exercised manually through home (closed) position a good 15 cycles by hand. Hope something helps here- software is overconstrained I think.

 

[Ram_Okie]

@jonnygobig I was planning on getting some throttle body cleaner and starting that process. From your replay it seems like you did this installed on the truck. Did you just cycle yours on the truck and not clean? I was thinking about taking mine off but I would think I should order a new gasket if I get to that point to just be safe. I found the appropriate torque specs of the TB bolts on the manifold (71 in pounds) so I can't imagine it would be that difficult. I did try and do a ETC Relearn on my 5160 RS but it kept giving me an error. I would think I would want to recalibrate the TB and pedal after doing that work but not sure why my reader wouldn't let me perform it.

 

[jonnygobig]

@jonnygobig I was planning on getting some throttle body cleaner and starting that process. From your replay it seems like you did this installed on the truck. Did you just cycle yours on the truck and not clean? I was thinking about taking mine off but I would think I should order a new gasket if I get to that point to just be safe. I found the appropriate torque specs of the TB bolts on the manifold (71 in pounds) so I can't imagine it would be that difficult. I did try and do a ETC Relearn on my 5160 RS but it kept giving me an error. I would think I would want to recalibrate the TB and pedal after doing that work but not sure why my reader wouldn't let me perform it.

Sorry for the slow reply! I did it in place, using lint free shop wipes. Start exercising by hand and you can feel a little sticky feed back in closed position about where it will be when this issue occurs. I just wiped until had clean wipes, make sure to exercise through full range of motion to hardtops.

Hope this helps!

 

[Ram_Okie]

So I checked the Throttle Body and it feels fine and there are no noticeable vacuum leaks.
I sprayed starting fluid all around the manifold to see if there was any leaks around the mounting surface.
I also sprayed at the base of the throttle body.
The vapor line on my EVAP solenoid seems weirdly loose at the connector but not sure if that is normal.

The P2173 is only active once I get to work and put the truck in park.
Before then there is nothing.
When I get back to my truck after work the CEL is illuminated because its a stored code but it is no longer actively tripped.

It tripped Monday when I got to work and I took it into the dealer Tuesday.
They told me they couldn't find the issue and that I would have to bring the Truck in the with the code actively tripped.
That seems bogus to me as it would be about a 30 mile drive in limp mode.

I think they couldn't find the issue quickly and were over booked.
They did say that I could leave the truck with them for them to put miles on until it tripped again
This is my only vehicle and it only happens about once a month so maybe 500 miles or so.
Would this be an option that you guys took or should I find a better mechanic?

Since its intermittent the tech pubs say I need to do a lot of harness checks.
Not sure what else to do here.