CX-5 doesn't run as well in the hot humid weather

W

wlong01

:
2019 CX5 Reserve AWD
Noticed a difference in performance when the temp is hovering around 90 deg and the humidity is moderate to high. Car seems to stumble a bit and gas pedal needs more pressure to move the car. Not sure if it's the weather, summer blend, a/c or a "combination of all of the above".

Car seems to perform best in the 50-65 degree range.

Anybody else notice this?
 
Hotter air is thinner then colder air, basic principal of science. It makes since that the performance suffers a bit at warmer temps, the air is less dense and therefore less oxygen per unit of volume going into the engine. Its why short ram and cold air intakes are popular, they allow more and colder, denser air to enter the engine.
 
As discussed in other threads, the slightly higher octane will keep the ecu from pulling a ton of timing in hot weather. It will still pull timing but no where near as much. These motors like a cool charge and when hot they go into different maps that greatly reduce power.
Heat soak is not a friend of our high compression motors,,,,, especially when ran on the lowest octane fuel available.

Seriously, if you have another week of 90* temps run a tank of higher octane fuel and report back!

Lots of discussion here about the need for better fuel, with lots of doubters, but there have been lots of reports that better fuel (octane) helps! No, it wont give you a magic 20HP boost over the stock 184 HP our cars came with but it will help with the major timing pull (loss of HP ) when hot/humid conditions are the norm!

Slightly better discussion about timing pull vs temp here: http://www.mazdas247.com/forum/showthread.php?123855100-Skyactiv-only-runs-at-80celcius/page2
 
Last edited:
davesxx01 said:
As discussed in other threads, the slightly higher octane will keep the ecu from pulling a ton of timing in hot weather.....
No, it wont give you a magic 20HP boost over the stock 184 HP our cars came with but it will help with the major timing pull (loss of HP ) when hot/humid conditions are the norm!
Click to expand...
I agree.

You can always try 89 or 93-octane gas and see your sluggishness is less severe. But I'd simply try a good top-tier regular gas such as Shell or Costco if you're not using it. After all we don't push our engine to 5700 rpm for full 184 hp all the time, top-tier regular gas as SkyActiv-G is designed for should be fine for us under most conditions.
 
I live in Houston - its as hot and humid as it gets :) Will try 93 octane next time and report back.
 
I guess I should add more info...... Our cars may be rated at 184 HP but as stated, when driving at 3K rpm on a nice cool day lets say the engine is making 100 HP (no exact science here, just a number) at the same rpm on a 90* day with high humidity the engine is probably only making 85-90 HP due to timing pull, baro pressure, load, ect. If you use slightly better octane you engine won't pull anywhere near as much timing as it would on 87 octane.
Your throttle will "feel" sharper because your engine isn't being held back as much.
Hope that makes sense to ya.

Try 89 octane to see if that helps!
 
Run 91+ octane to prevent or limit timing being pulled

That way you can see the full 185HP of the 2.5L (rofl2)
 
I do not feel any power loss in the heat and mine gets better milage in high temps with AC going than at lower temps with no AC...
 
wlong01 said:
Noticed a difference in performance when the temp is hovering around 90 deg and the humidity is moderate to high. Car seems to stumble a bit and gas pedal needs more pressure to move the car. Not sure if it's the weather, summer blend, a/c or a "combination of all of the above".

Car seems to perform best in the 50-65 degree range.

Anybody else notice this?
Click to expand...

A/C and a combination of timing retard due to the heat, IMO. I know modern A/C systems are not supposed to drag much, but back when I had a WS6, I raced a guy in a modded camaro from a freeway roll. The first run, I left the A/C on (it is supposed to kick the compressor off under certain load/rpm). I then ran him again with it off. There was significant difference.
 
Chris_Top_Her said:
Excuse me, it's only rated at 184hp.
Click to expand...

Haha, it's easier to just round up, even the IRS allows one to round up. Everyone except a certain forum member who blows his gasket if you post 185HP instead of 184HP. It's a form of OCD I guess :)
 
wlong01 said:
Noticed a difference in performance when the temp is hovering around 90 deg and the humidity is moderate to high. Car seems to stumble a bit and gas pedal needs more pressure to move the car. Not sure if it's the weather, summer blend, a/c or a "combination of all of the above".

Car seems to perform best in the 50-65 degree range.

Anybody else notice this?
Click to expand...
Shouldn't be running that way particularly with the stumbling with fuel injection, get it checked out. I've had no problems in any temperature, maybe you have a sensor or something on the fringe. Higher octane might help but it might be only a bandaid. Are you using only Top Tier fuels?
 
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madar said:
Shouldn't be running that way particularly with the stumbling with fuel injection, get it checked out. I've had no problems in any temperature, maybe you have a sensor or something on the fringe. Higher octane might help but it might be only a bandaid. Are you using only Top Tier fuels?
Click to expand...


Yep, ExxonMobil. It's probably the weather. Went out today, temps were in the low 70's and it ran normally. A/C was set down low where the compressor didn't have to kick in much. Maybe it's just me.
 
Lbear said:
Haha, it's easier to just round up, even the IRS allows one to round up. Everyone except a certain forum member who blows his gasket if you post 185HP instead of 184HP. It's a form of OCD I guess :)
Click to expand...

Chris is competitive and OCD. That blend of passion is what progresses performance. When you are reaching diminishing returns on an already efficient engine, each HP gain is hard-fought and costly. Rounding a number marginalizes the effort. Besides, it is already a whole number.
 
So hotter temps equal lower performance...who knew?

Must be why they have the SAE correction factor on dynoes. :)
 
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