P0505 Suddenly lost all power, barely idles.

[BoofinBrettK]

On my second trip after doing some work to the FiST, something has gone funky. I've ran a KOEO and OFF and the only code I get consistently is p0505. Would that point to the throttle body?
I've checked for vacuum leaks, tested all the check valves and the purge valve, all working like they should and not blocked.

Swapped out the boost sensor and map sensor.

Car will start up just fine and run fine for a couple seconds then go super rough, sometimes dying.

Runs a little better if I pull the EVAP line off the front of the throttle body but not totally fine.

Poor car has been sitting at the end of the driveway for weeks now, riding the bike kinda sucks in this heat🔥

 

[Dialcaliper]

Is the problem that it just won’t idle? Will it run okay if you give it a little gas after you start it, or is it constant?

If it’s an Idle problem only, it might be a bad idle air control valve.

Which Evap line did you pull? The one on the front of the manifold that’s above the throttle body (see attached picture) or a different one? Pulling the post throttle body Evap line in the photo should cause the engine to rev up rather violently and hit the rev limiter (ask me how I know when I forgot to hook it up 🤣).

If it doesn’t do that or also doesn’t run right when given throttle the problem is likely elsewhere, maybe fuel or ignition system. Check that coil packs are seated as a first step and pull the spark plugs to see if anything obvious is going on there (rich/lean/fouled)

 

[BoofinBrettK]

I will Idle roughly when I start the car up. If I give it gas it definitely runs better till I let off the gas.
When I let off the throttle, the car will chug out and die pretty quick unless I give it a small amount of throttle before it does.

The part you have pointed out is what I pulled. Popping it out makes it idle almost totally fine.
A little high but not going full throttle by any means.
I'm going to swap some new plugs in, mine had gotten oil on them from a leaking valve cover, thought I'd get a misfire code if they were bad though.

 

[SteveS]

That code typically means a dirty or defective idle air control valve.

 

[Dialcaliper]

I will Idle roughly when I start the car up. If I give it gas it definitely runs better till I let off the gas.
When I let off the throttle, the car will chug out and die pretty quick unless I give it a small amount of throttle before it does.

The part you have pointed out is what I pulled. Popping it out makes it idle almost totally fine.
A little high but not going full throttle by any means.
I'm going to swap some new plugs in, mine had gotten oil on them from a leaking valve cover, thought I'd get a misfire code if they were bad though.

Codes are weird - sometimes they are accurate, but the ECU is basically looking around with a blindfold for odd signals or behaviors, and it doesn’t always catch it till it gets really bad and sees a very obvious pattern of signals either repeatedly or for a long enough duration to avoid flagging false codes. Basically it looks at symptoms and has no idea of the actual cause.

Pulling the hose I pointed to should definitely cause the engine to rev to redline (basically it that allows air from outside to bypass the throttle plate). Check the idle valve, but it’s likely something else. All that code really means is that the ECU is having trouble controlling the idle.

 

[BoofinBrettK]

That code typically means a dirty or defective idle air control valve.

Do we have an IAC valve in the ST180?

 

[BoofinBrettK]

Codes are weird - sometimes they are accurate, but the ECU is basically looking around with a blindfold for odd signals or behaviors, and it doesn’t always catch it till it gets really bad and sees a very obvious pattern of signals either repeatedly or for a long enough duration to avoid flagging false codes. Basically it looks at symptoms and has no idea of the actual cause.

Pulling the hose I pointed to should definitely cause the engine to rev to redline (basically it that allows air from outside to bypass the throttle plate). Check the idle valve, but it’s likely something else. All that code really means is that the ECU is having trouble controlling the idle.

I'll give the plugs a swap and see what happens tomorrow.
One of my coil packs has a little warpage on the rubber boot, doubt that my issue but thought I'd mention.

 

[BoofinBrettK]

I'll give the plugs a swap and see what happens tomorrow.
One of my coil packs has a little warpage on the rubber boot, doubt that my issue but thought I'd mention.

Might have to wait a few days on shipping for the plugs actually

 

[Dialcaliper]

Do we have an IAC valve in the ST180?

Hmm - looking at the parts catalog (Tasca), I think you're right - there's just the throttle body with two electrical plugs, one for the motor and one for the position sensor - no separate idle control valve and no wax valve. Everything is controlled electronically between the throttle plate, direct fuel injection and ignition timing, so basically it has to be a problem with one of those three systems. Unfortuntately the 2014 service manual is sparse on details and there's a separate "Powertrain Control and Emissions" manual that's referenced everywhere that I haven't been able to get my hands on - it deals with all of the actual engine control systems.

 

[TyphoonFiST]

Replace the Throttle body* buy one off amazon Their like $65. Mine failed and would be rough from time to time and then it started to Get stuck closed and shut the car down completely whike driving and throw the wrench light.

 

[BoofinBrettK]

Hmm - looking at the parts catalog (Tasca), I think you're right - there's just the throttle body with two electrical plugs, one for the motor and one for the position sensor - no separate idle control valve and no wax valve. Everything is controlled electronically between the throttle plate, direct fuel injection and ignition timing, so basically it has to be a problem with one of those three systems. Unfortuntately the 2014 service manual is sparse on details and there's a separate "Powertrain Control and Emissions" manual that's referenced everywhere that I haven't been able to get my hands on - it deals with all of the actual engine control systems.

I've been using this guy's site for the service manual. I didn't see powertrain control and emissions on a cursory search but might be there
Service manual for Fiesta

 

[BoofinBrettK]

Replace the Throttle body* buy one off amazon Their like $65. Mine failed and would be rough from time to time and then it started to Get stuck closed and shut the car down completely whike driving and throw the wrench light.

Just changed out my plugs and it helped a bit. I didn't try to drive it around because it's still chugging after hitting the throttle.
New TB is $110 at O'Reilly. I'll swap mine out this weekend and I hope that gets me back on the road. If that doesn't get me going I'll have to roll it to a shop

 

[BoofinBrettK]

Back today with a brand new throttle body, did not fix my issue. Not sure what to do other than save up for a tow and find a shop that works on these cars. Made a video showcasing how it's behaving, maybe it'll be obvious to someone who's been here before 🤞Video of Sad ST

 

[BoofinBrettK]

Threw in the towel and called a tow truck. I will report back to this thread with the results 🤞🤞

 

[BoofinBrettK]

Shop says it's jumped timing. Engine is probably fucked so I guess it's getting parked indefinitely.

 

[kivnul]

Damn. Hopefully it is not fucked. Good luck.

 

[waverider57]

That code typically means a dirty or defective idle air control valve.

That code can mean anything that interferes with a smooth idle, including bad gas, oil in the charge pipe, a dirty Maf sensor, even a broken turbo shaft causing exhaust to enter the compressor side of the turbo. There is no IAC valve on the Ford FiST, btw. I’ve noticed that a lot of rumor and heresay go as facts in this forum. Don’t guess, it makes you look bad, and wastes others time. Sorry, it’s a fact. .