Direct injection engine struggles to warm up(Mazda 2.5NA) am I overreacting?

[Rally2045]

Hello,

I have a 2020 Mazda 3 has an issue getting up to operating temp. Both of the coolant sensors agree, the car is running cold. Unless I drive aggressively, in 10-40F temps, it struggles to get above 140-160F when I have the heat on.

This is a fairly well known issue, and there’s a TSB for it. https://static.nhtsa.gov/odi/tsbs/2023/MC-10248393-0001.pdf

The issue is that to fix it under Powertrain warranty. they want the check engine light to be set. Apparently either mine is mild enough not to trigger the light, or I’m not driving in the correct way for it to go off.

To replace the parts myself would be about $500, and that’s with DIY labor, as this car uses a fancy electronic coolant valve with an integrated thermostat. There’s also the issue that some people are apparently having to have this repair done multiple times.

Would you do this on your own dime? I’m just picturing carbon building up on my intake valves and it’s bothering me I admit.

I’ve written corporate and done all of the advocacy I can for a warranty fix and I’m going nowhere.

 

[ctechbob]

GDI Engines just don't warm up fast. I have datalogs from my Ranger, and that is a turbo engine (and a cousin to your 2.5)where it really struggles getting up to temp. On cold days there just isn't enough heat being made. The ECU knows it is completely normal or it would set a cold coolant code.

When it is cold outside, on my 14 mile drive home the truck will just BARELY get to 190 deg, and that is stop and go driving along with a 60 mph stretch.

Here's a log of my trip in to work, it gets up to 195, but then falls back down puttering through town with the heat on.

The trans never gets up to temp when it is cold out.

I wouldn't worry unless it sets a code.

datazap.me | ctechbob | Log 1705823547

datazap.me

 

[t1snwrbrdr12]

I guess mine is different bc it isn’t listed in that TSB (I have a 2017.5 Mazda 6), but I complained about lack of heat and they told me nothing was wrong. Anything mid 30s or colder and it struggles to get near the middle of the temp gauge, then as soon as I use the heat it dips back down to a notch above the cold indicator…same thing if I hit the highway, it’ll cool off. I’ve just become used to it but I still don’t like it.

Have driven a newer bunch on Hondas as loaners in the same conditions for when our new van had issues and none of them have this issue at all, in fact they’re warm and providing heat before I’m even out of my neighborhood. My old k24 Honda warmed up super fast as well.

 

[Jetronic]

Not a mazda but my diesel never got to operating temp before the cabin was close to the set temperature, and the heater fan calmed down to half speed or less. The temp gauge would climb a bit higher going uphill, then drop again going downhill. But I never had it in temperatures as low as 10F.

Never triggered any warning lights or codes.

I'm going to fit an aux heater on my coming t-gdi like Bailes1992 did with his Dacia. It would allow the heater to run at minimal speed and the engine to get hot.

 

[eljefino]

Does that car have grille shutters? If not I would try rigging up some cardboard over half the radiator (the half without the fan.) My Saturns used to lose heat going down hills even with good thermostats so I covered the rad. This also helped reduce the air blowing through the engine bay, over the engine itself and its oil pan, which rejects ~30% of the heat.

It might seem ghetto with a new car but having the rest of the stuff under the hood closer to a decent temperature will be helpful.

 

[KrisZ]

Your Mazda should have a manual shift option. I would use that to keep the revs in the higher range during warmup.

Otherwise it looks like we are back to the old school days of covering the front grills with cardboard boxes.

 

[BMWTurboDzl]

Hello,

I have a 2020 Mazda 3 has an issue getting up to operating temp. Both of the coolant sensors agree, the car is running cold. Unless I drive aggressively, in 10-40F temps, it struggles to get above 140-160F when I have the heat on.

This is a fairly well known issue, and there’s a TSB for it. https://static.nhtsa.gov/odi/tsbs/2023/MC-10248393-0001.pdf

The issue is that to fix it under Powertrain warranty. they want the check engine light to be set. Apparently either mine is mild enough not to trigger the light, or I’m not driving in the correct way for it to go off.

To replace the parts myself would be about $500, and that’s with DIY labor, as this car uses a fancy electronic coolant valve with an integrated thermostat. There’s also the issue that some people are apparently having to have this repair done multiple times.

Would you do this on your own dime? I’m just picturing carbon building up on my intake valves and it’s bothering me I admit.

I’ve written corporate and done all of the advocacy I can for a warranty fix and I’m going nowhere.

Sounds like a coolant circuit design issue because the automaker has every incentive to get the engine up to operating temps as quickly as possible.

It would be interesting to see from where the hose leading to the heater core originates.

Zoom..Zoom..to keep the heat on. hehe. (sorry, but I had too)

 

[vpr5703]

My 2018 Mazda6 w/ the 2.5NA took a little while to get hot in the cold months as well. I live on a rural 55MPH road, and it would be around 175F after 10 minutes unless the temp was in the single digits. Once I got on the highway after the 10 min drive it came up to temp within 5 minutes.

 

[JTK]

Is it a GDI thing or is it more dependent on the overall vehicle design?

I know my Subarus had terrible HVAC output overall for me. A 2014 Crosstrek and a 2016 Forester. One was a 5MT, the other CVT. These were port injected. My 2022 Nissan Frontier takes a good 10 miles of driving before you get decent heat. It's GDI.

 

[vpr5703]

Is it a GDI thing or is it more dependent on the overall vehicle design?

I know my Subarus had terrible HVAC output overall for me. A 2014 Crosstrek and a 2016 Forester. One was a 5MT, the other CVT. These were port injected. My 2022 Nissan Frontier takes a good 10 miles of driving before you get decent heat. It's GDI.

I think it's an engine/vehicle design thing. My MIL has a 2004 ranger with a 3.0L V6, and that thing takes FOREVER to get up to temp. Long than any of my GDI cars.

 

[Rally2045]

GDI Engines just don't warm up fast. I have datalogs from my Ranger, and that is a turbo engine (and a cousin to your 2.5)where it really struggles getting up to temp. On cold days there just isn't enough heat being made. The ECU knows it is completely normal or it would set a cold coolant code.

When it is cold outside, on my 14 mile drive home the truck will just BARELY get to 190 deg, and that is stop and go driving along with a 60 mph stretch.

Here's a log of my trip in to work, it gets up to 195, but then falls back down puttering through town with the heat on.

The trans never gets up to temp when it is cold out.

I wouldn't worry unless it sets a code.

datazap.me | ctechbob | Log 1705823547

datazap.me

View attachment 210271

I have occasionally seen a pending P0126, but it never actually sets as a confirmed code.

I understand that a lot of these modern engines seem to take awhile to warm, but for reference I drove 25 minutes/25 miles, almost all freeway to work and it was reading maybe 140F at the end of that.

Heat was on but I was just trying to stay comfortable and I wasn’t intentionally trying to blast it on max the entire time or anything.

 

[Rally2045]

Sounds like a coolant circuit design issue because the automaker has every incentive to get the engine up to operating temps as quickly as possible.

It would be interesting to see from where the hose leading to the heater core originates.

Zoom..Zoom..to keep the heat on. hehe. (sorry, but I had too)

I’ve done some research, I have a bootleg copy of most of the Mazda service information on my computer as well, so I know a fair amount about the cooling system.

My understanding is that by design, the cooling system of this car is supposed to be regulated by an electronic valve, which opens on ECU command, to allow coolant to flow to the radiator, A/T heat exchanger, and I believe from the heater core.

That being said there’s a backup system inside this valve that is an old school thermostat and opens the radiator coolant loop, and that is opening too early.

 

[GMBoy]

There is nothing different about a GDI vs non GDI as far as temps are related. My DI cars reach operating temps just as quickly just as non DI. You clearly have an issue and the TSB proves it - go to the dealership and voice your concerns about deposits etc and that it is polluting more at cold temps. I would not repair it myself.

 

[bobdoo]

HA! I just datalogged my CX-5 this morning.

40 minutes driving 65-75 mph. Engine hit 190ish at about 30 minutes, tranny hit 185ish around 40 minutes, and the diff got up to a balmy 105ish somewhere around 25-30 minutes.

Here's HP and torque: https://mazdas247.com/forum/t/comparing-mx-to-dyno.123880915/

 

[ctechbob]

There is nothing different about a GDI vs non GDI as far as temps are related. My DI cars reach operating temps just as quickly just as non DI. You clearly have an issue and the TSB proves it - go to the dealership and voice your concerns about deposits etc and that it is polluting more at cold temps. I would not repair it myself.

Are you looking at the needle on the dash or actual data?

And what kind of ambient temps are we talking.

 

[Exhaustgases]

Drain all the coolant out and you will see it will jump to a nice high temperature real quick.
GDI or No GDI.
Right on GMBoy.

Only time GDI could be affecting temps and warm up time is if it was using the diesel engine throttling scheme.

 

[GMBoy]

Are you looking at the needle on the dash or actual data?

And what kind of ambient temps are we talking.

ALL the data on scan tool and gauge on dash and ALL temps 0 - 110 degrees. My point was his car is having a known issue (TSB issued) on why it's running cool. Also temp need to be high for emissions purposes and so the engine is most efficient.

 

[GMBoy]

Drain all the coolant out and you will see it will jump to a nice high temperature real quick.
GDI or No GDI.
Right on GMBoy.

Only time GDI could be affecting temps and warm up time is if it was using the diesel engine throttling scheme.

Exactly! The only difference in GDI is where the injectors spray the fuel.

 

[Rally2045]

Unfortunately I’m traveling for work and away from my car, that being said I did record one graph with data before leaving. This was from driving and idling, the car wasn’t off at any point. I do live in a mountainous area, so I was going up and downhill.

Also sorry about the time axis, feel free to divide by 60.

I do want to to a more normal test with flat terrain at some point.

 

[KrisZ]

Yeah, that’s quite a fluctuation going on there. It Doesn’t look normal in a conventional sense, but if this is intentional one begs the question, what is the benefit of running the coolant temp up and down like that?