So tell me about hot limp mode

[Reaper]

Is this limp mode? I'm 3/4 thru a rallycross course in 105F temps and I hear a faint ding ding ding coming from somewhere and suddenly my power is cut way back. I see nothing on the dash or info screen. My cheapie code reader says no codes. The limp mode is gone when I shut off and then restart the car. But it happens again on the next lap at the same place. Call it a day, trailer it and take last place.

On top of that it still misfires when hot idling and longer than a minute or so it throws one of three misfire engine codes. No change after new NGK plugs and coils. But at least car runs fine and the codes usually go away on their own. Otherwise I reset them with the cheapie reader.

Very low mileage stock engine with only a 91 octane Stratified tune. But Ford won't even look at it because of the tune.

 

[NATYPE]

Feels like you'd have to be seeing some high coolant temps (or something) to approach that kind of scenario, any ID on anything like that creeping up on you? This happened twice on my old 2015 non ST.

 

[Dialcaliper]

When it happened to me, I heard the “ding ding” and then lost power, and when I had the presence of mind to check the dash display, the LED temp gauge was over to the right (only one bar on the gauge was blank, instead of being in the middle) and the thermometer light on the dash lit up. So I pulled over - it happened pretty quickly after I started driving uphill

Word of advice. If it happens again, *do not* turn the car off. Pull over and let the car idle so the water pump keeps runningfans and radiator can still cool the engine block back down. pop the hood if you can and check your now boiling coolant tank. Keeping the hood open will also allow the hot air coming out of the radiator to exhaust more easily than pushing into the closed engine bay.

When the engine stays hot without cooling available, the hot parts start to heat soak and equalize temperature (normal temperature gradient from head and combustion chamber through walls to coolant reverses direction because the hot coolant keeps the block hot) while other parts will be cooling down, and that’s when there’s a higher chance for warpage to happen.

If the coolant level is still full, the car cools back down fairly quickly at idle, and you’re not spewing coolant everywhere, the engine and cooling system are probably going to be fine (the limp mode is there to protect the engine), but you might consider looking into better cooling options (i.e. better radiator)

The only time you should shut the car off for overheating is if at idle, the temperature keeps rising instead of coming back down, which usually means a coolant leak and low coolant level, complete water pump failure or something else nasty, in which case you’ve got a different problem.

If you’ve blown a head gasket and coolant is leaking into your oil, you’ll see white smoke (steam) out the exhaust. Oil in coolant should show up as sludge in your coolant reservoir.

If none of those have happened, you’re probably fine and just have a normal inadequate Fiesta radiator in the car that won’t hold up to the style of driving you want to do

 

[Jabbit]

That's when you reach a certain age and see an attractive person but can't do anything about it.

Kidding aside, log some runs with the Accessport and see if you can correlate any data. I suspect coolant temp too high.

 

[Dialcaliper]

Almost forgot to mention, but I plugged in Forscan the other day, and there was a P0217 over temperature error code from the day I overheated, along with another code which I’ve forgot the number, but seemed to indicate going into limp mode.

The details for both labeled them as not triggering any warning or check engine lights, so you have to use a proper scan tool to see if they are there (Accessport might pick them up if you have one, otherwise download Forscan and a buy a $40 OBD port dongle)

https://forscan.org/home.html

 

[Reaper]

So how do I go about "learning" Forscan? Is reading a manual good enough or is there an on-line tutorial somewhere? Is there a particular OBD dongle that's the go-to for FiST? This cable adapter seems popular on Amazon and they say they have Forscan approval.
https://www.amazon.com/OBDLink-EX-F...6-49d0-877e-c555f49bd267&ref_=pd_gw_ci_mcx_mi

Ahh -- found these:
https://www.fiestastforum.com/threads/forscan-basic-info-and-getting-started.19945/

.

View: https://www.youtube.com/watch?v=ZvkkQZFIzyA

 

[BillSchm]

I have a 2019 FiST and had an overheating problem almost immediately when climbing out of the Phoenix valley at 110 degrees. I also kept the motor running and limped up the hill after pulling over and letting the temp gauge go down a bit, then drive a little more, etc.

I swapped in a Mountune radiator and have nad no problems since. I think the issue is that the standard Fiesta radiator is fine for most of the Fiesta versions, but is undersize for the ST. Simply that.

 

[Dialcaliper]

So how do I go about "learning" Forscan? Is reading a manual good enough or is there an on-line tutorial somewhere? Is there a particular OBD dongle that's the go-to for FiST? This cable adapter seems popular on Amazon and they say they have Forscan approval.
https://www.amazon.com/OBDLink-EX-F...6-49d0-877e-c555f49bd267&ref_=pd_gw_ci_mcx_mi

Ahh -- found these:
https://www.fiestastforum.com/threads/forscan-basic-info-and-getting-started.19945/

.

View: https://www.youtube.com/watch?v=ZvkkQZFIzyA

For Forscan, the list the adapters on the front page - I bought the Vlinker one
https://forscan.org/home.html

First rule of forscan is to back up *everything* for any module before you change anything by hitting Save once you open it.

Reading the diagnostics is pretty straightforward - there are some videos online if you need info

Second is that if you decide to get the extended version so you can change things in the car, the Fiesta uses “central configuration” which means most changes happen either in IPC module or BCM module that list “central configuration” changes. Basically it means you don’t need to change every module individuall

 

[cidsamuth]

For me on the track with the stock radiator, I started overheating with the ambient only in the 70s. It started to noticeably lose power, and I looked at the Accessport to find engine temps had approached 245 degrees. I stayed out and just eased up, and the temps dropped to under 240 -- the power then came back. Did that cycle the rest of the session, then called it a day. The overheating light came on at some point but, interesting enough, not until after the computer starting pulling power.

Had a Mishimoto radiator in it by the next weekend. Temps are obviously better now and a non-issue even on really hot days at the track. Although I will note, once I accidentally went out on the track with the A/C blowing full on during a 90+ degree day, and the car still got to 235+ even with the Mishimoto. Since then, I've been extra careful to ensure the A/C goes off as I leave the staging lanes, and temps have never exceeded 220 even under the harshest conditions.

 

[Erick_V]

Have a Mountune Rad and I got pretty close to 230 by the end of my 3rd 20 minute session. I believe ambient temp was around 90. Popped the hood, blasted heat and let it run while I logged tire pressures and before I turned it off it was already around 200 (OEM 2016 thermostat).

I see you’re in San Diego, you could get away with running a 70/30 water/coolant mix with water wetter. Even with Texas heat at 100+ and the AC blasting I’ve never been close to overheating on the street.

Only problem I have with the Mountune Rad is because I didn’t overheat I blew through an entire tank of E30 at my track day, had 20 miles to empty when I pulled in at the end of the day. Pick up an OEM rad bleeder too, mine broke when I uninstalled it. Lastly, AFAIK the biggest oil filter you can run with the Mountune is the FL400s FoST filter.

 

[Intuit]

Kind of reminds me of that one person's vehicle that wouldn't let him drive, in the same spot on the track because it thought he had a wreck. I guess there was a turn with a bump on it or something the car's shock sensor(s) didn't like. I think his cut all throttle rather than just reduce power... I think.

............... AFAIK the biggest oil filter you can run with the Mountune is the FL400s FoST filter.

Ran those on my 1994 vehicle. That was a SOHC 1.9L 88HP engine. 🙂 At some point, maybe a decade ago, they downsized it. Probably still bigger than the can in that cramped space between oil cooler and radiator though.