Is power limited when ambient temperature is under 38F?

As discussed with you previously via email, we (@Formidable and I) determined via testing that under 38F the ECU was limiting via an application of throttle limiting, almost certainly a safety system

 

Your welcome.

Yeah. One of the YW testers was having a bad time dealing with this. Most dyno shops are open up for runs. The power limitation below 38F could ruin the day.

 

Marc,

We discussed it but didn't come to a conclusion.

Do you know which sensor the ECU is using to determine ambient temperature? Could it be the sensor that feeds the console temperature display? (The sensor by the hood latch)

 

I don't understand where this is coming from; like I wrote above, unless the throttle butterfly is being limited to how far it can open, then the engine WILL produce more power the colder the air gets. Once again, simple physics.

 

It's not like we can confirm whether or not we have access to every table. I chalked it up to an unavailable table which is basically a guarantee if it's a safety system

 

Could even be in a completely separate ECU, like the Skid Control.

 

If I had to make a wild guess I would say the intake air temp sensor. Probably much harder to trick than the front ambient temp sensor.

Dont the dynos have heated shops?

 

Not the one I go to. I live in WV so I am lucky there is one within a 2 hour drive of where I live.

 

Intake air temperature sensor is integrated into MAF

 

Dang. I didn't consider the tune with my previous message. That would make sense then if it was tuned to be that way. I wonder if the OTT tune would remedy that issue, looks like they're making pretty sweet power with that tune as well.

 

Yes. Not sure of an easy / safe way to trick that without a heated shop or some large source of warm air to draw into the intake

 

It's an ingrained thing.

 

Second winter with my truck and the first real cold day here this year (-25c) my truck absolutely struggled in the cold. I was just getting on to the highway, wasn't quite at full temp, and even with the pedal to the floor in fourth and fifth gear I couldn't get the engine speed up and I couldn't get the truck above 90km/h. Eventually it just started running as it normally would and hit 110km/h in 6th with no issues.

Hadn't happened before and hasn't happened since even though it's been colder.

It was definitely strange.

 

No issues with power here. This is my weather for the last 10 days. Like this every winter. Only thing I’ve ever noticed is sluggish steering.

 

Maybe those "cold" air intakes which suck warm engine bay air will finally have a place

 

On stock trucks it is. On Magnuson equipped vehicles it is moved onto the blower to get a more accurate temp.

 

I know some performance cars will limit engine output until the computer deems they have been fully warmed up, some might not even let you know when they have warmed up. A rule of thumb is your engine temperature is over 180°.

Cold air, for the most part is actually very dense, so your engine should be getting better airflow when it’s cold.

 

Tricking it also sounds like messing up your fuel air ratio. Mind you once the engine comes up to temp the only thing that should need to be heated is the intake air.

Maybe off the wall but makes me think of something like those Chinese diesel heaters ducted up next to the air intake. (Combustion exhaust is piped separate from the heated air duct on those)

 

Do you have a supercharger?

 

I can't imagine noticing a lot of difference at a balmy 20F, but when it gets to 0F or thereabouts I have noticed some sluggishness in all automobiles I've owned until they warm up. I've always assumed it is a combination of cold stiff drivetrain oil causing greater viscous resistance, cold stiff tires causing greater rolling resistance, and cold dense air causing greater air resistance.