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Discussion Starter · #1 ·
Return of my dreaded P2172, original thread here: Mystery hose connection under airbox

Summary: In chilly weather, when the car (2013 Abarth with stick) is partially warmed up, it will flip into limp mode and start revving, but only when I am stopped. I can shut off the car and start it again, if I do that within a few seconds it stays in limp mode; but if I give it 5-10 seconds before starting it again, it will run just fine. Throws codes P2172 P1046 P1048 P104A P104C.

I am using 5w40 synthetic oil that meets specs 10725 and 12991, filled to exactly the top of the hatches on the dipstick.

Fiat studio replaced throttle body and MAP sensor. I have replaced the Air Oil Separator & PCV as well as the stoplight switch, all using genuine Mopar parts. I performed the repair on the trunk lid wiring (jackets had rubbed through so I rewrapped the individual wires and then re-sheated the whole thing). To the best I can tell the car is stock, although I do wonder if a previous owner had modified it and returned it to stock before selling, or the engine was replaced at some point in its life. I have visually inspected the vacuum lines around the evap system wrapping around the back and sides of the motor, as well as shot some starting fluid around while running, to listen for a reaction, so I think I probably do not have a vacuum leak.

I thought I had the right tool for checking the crack pressure of the wastegate actuator (appears to be OEM, unmodified), although my tool is vacuum-only and apparently I need one that I can use to build pressure. I think that's my next step, but I'm looking for other ideas. There's the EVAP purge valve above my intake, or the wastegate solenoid down by the timing cover, although I don't want to just throw parts at it if I can test/confirm those.

The only other clue I have is, this seems to be a chilly weather problem. Didn't happen until I started driving it in 40 degrees or so, anything above that it has run great with absolutely zero issues.
 

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Return of my dreaded P2172, original thread here: Mystery hose connection under airbox

Summary: In chilly weather, when the car (2013 Abarth with stick) is partially warmed up, it will flip into limp mode and start revving, but only when I am stopped. I can shut off the car and start it again, if I do that within a few seconds it stays in limp mode; but if I give it 5-10 seconds before starting it again, it will run just fine. Throws codes P2172 P1046 P1048 P104A P104C.

I am using 5w40 synthetic oil that meets specs 10725 and 12991, filled to exactly the top of the hatches on the dipstick.

Fiat studio replaced throttle body and MAP sensor. I have replaced the Air Oil Separator & PCV as well as the stoplight switch, all using genuine Mopar parts. I performed the repair on the trunk lid wiring (jackets had rubbed through so I rewrapped the individual wires and then re-sheated the whole thing). To the best I can tell the car is stock, although I do wonder if a previous owner had modified it and returned it to stock before selling, or the engine was replaced at some point in its life. I have visually inspected the vacuum lines around the evap system wrapping around the back and sides of the motor, as well as shot some starting fluid around while running, to listen for a reaction, so I think I probably do not have a vacuum leak.

I thought I had the right tool for checking the crack pressure of the wastegate actuator (appears to be OEM, unmodified), although my tool is vacuum-only and apparently I need one that I can use to build pressure. I think that's my next step, but I'm looking for other ideas. There's the EVAP purge valve above my intake, or the wastegate solenoid down by the timing cover, although I don't want to just throw parts at it if I can test/confirm those.

The only other clue I have is, this seems to be a chilly weather problem. Didn't happen until I started driving it in 40 degrees or so, anything above that it has run great with absolutely zero issues.
Just out of curiosity - what's the outside temperature reading? Is it accurate?
 

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Discussion Starter · #3 ·
Yeah, the dash readout is usually within a couple degrees of my outdoor thermometer. Interesting question, wondering if the ambient tempt sensor was giving an incorrect value resulting in it feeding the wrong volume of air?
 

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I asked because I had an issue with ambient temperature sensor, and it occasionally threw CEL, but only when there’s a distinctive seasonal change in outside temperature. But if yours is reading correctly, it probably isn’t it. Is there anyway that you can try another PCM?
 

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Discussion Starter · #6 ·
Heck, used PCMs are pretty cheap on the auction site…. May be worth snagging one anyways.

My experience with other vehicles is that I can’t just swap it though, it has to be programmed. That the case here?

My train of thought is if I were going to a dealer to program it, then I may as well be paying a dealer to reflash my own.
 

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Discussion Starter · #7 ·
Returning to the idea that, fundamentally, extra air is finding its way into the intake - I'm questioning the purge valve system, as disconnecting that hose seems to offer improvement (with some limited testing). Getting the valve and the solenoid and will replace those next. Part numbers for historical reference. Cost me around $110 delivered to my door.

4627336AA
4627182AA
 

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Discussion Starter · #8 ·
Replaced the 4627182AA today - simple enough job, remove the intake assembly, slide hose off left barb, squeeze green tabs on upper hose on the right, slide white tab underneath electrical connector to the DS of the car and then squeeze the connector on the bottom while pulling, to release it. Test drive shows ok, although this happens every couple days so not certain yet. Specifically waiting on the other piece, so I can see if one of them is the fix, which one it was.
 

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Discussion Starter · #9 ·
Noting, I had previously left the "intake manifold to PCV" hose disconnected, and capped off the intake manifold hose barb. I returned that to OEM condition by reconnecting the hose (since I realize I shouldn't be troubleshooting having modified the system like so). Still have the new 4627182AA in place, and symptoms haven't returned. Fingers crossed.
 

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Discussion Starter · #10 ·
Of course I spoke too soon. The same five codes appeared, with a new variable: P0106 has entered the chat. So I cleared them out and replaced 4627336AA which was an enormous PITA. Single torx screw, one vacuum hose, one electrical connector, but it's all on the back/bottom of the intake manifold. Just high enough that going from below is tricky, and just far enough back that it was annoying to get my hands back there.

Anyways, problem returned, now including P0106 which is joining the party. My next step is swapping the charcoal canister at the rear of the car, because at this point I'm basically following all these little emissions hoses and looking for cracks (not finding any) and that's the next stop on the system. I also see some kind of valve/solenoid mounted to the strut tower on the passenger side, behind the coolant expansion tank, not sure what that's called. I'm also curious about a faulty PCM/ECU, but would like to learn more about what's involved in replacing that, if that's the case.
 

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Discussion Starter · #11 ·
I took one more crack at the emissions system with the vapor canister under the rear of the car (followed the hoses from my intake manifold through the valves I replaced above and landed here next). Mopar 68233276AE for historical reference. Part I installed was much lighter than the one I removed, but no success. Limp mode returned.

Following the Evap system hoses, there’s also a valve or solenoid behind the coolant expansion tank. Going to see where that road takes me next, I think. Any chance someone knows how to test it or what it’s called?
 

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Hey, thanks for keeping this updated. I'm totally out of suggestions! I mean, you pretty much replaced all the potential trouble pieces! At this point, I'm tempted to say PCM. Keep us posted.
 

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Discussion Starter · #13 ·
Latest update. The dealers all swore up and down there was no new flash available… turns out there was this one from 2015. I finally got that done, good news is that it cleared up the P1046 P1048 P104A and P104C codes. Bad news, didn’t fix the limp mode issues. Though now they only trigger a P2172 and P0106.

Im not sure if I should keep on the emission system or return to the idea of a vacuum leak, but there are more hoses around the timing belt cover that I didn’t check before (when I was spraying around the engine bay). That’s my next step I think, although I’m inclined to think that should yield boost problems if that’s the case.
 
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