Different IATs temps

[Waffles_s4]

Hi,

Am seeing two different IATs temp sensors, as attached in the pics. Which one does what, and which one is more accurate for measuring IATs? When car is hot, there is 10C or more difference between the two. 20190831_150425.jpeg

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[s4matty]

There is pre and post compressor temp sensors
The one on back of charger is pre and the 2 on the sides of charger are post after being compressed
The 2 side are actually the temp that is getting feed into the cylinders.
i focus on those

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[Waffles_s4]

There is pre and post compressor temp sensors
The one on back of charger is pre and the 2 on the sides of charger are post after being compressed
The 2 side are actually the temp that is getting feed into the cylinders.
i focus on those

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So which is which based on my screenshot?

[Rodizzle]

Second is your post . That’s what you wanna focus on


IAT
-IDE04000 (Temperature intake sensor)
-IDE04003 (Charge air temperature sensors for B1 and B2)
-ENG101471 (average of the above two sensors.)



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[Waffles_s4]

^^ Thanks, but why would there be say 10 or 15C difference of the two when the car is sitting with engine off (after a long drive)?

My IATs look normal-ish when driving (below 60C most of the time) but when I check the IATs after the engine is off for 20 min, the IATs go up to 70+C. I bled the SC yesterday (thanks TC), but am not sure why IATs creep up 20-30C when engine is off.

[theweebabyseamus]

Because the air has just been sitting there heating up and there is no flow through the I/C system to cool them down. Takes a little bit of driving, maybe a minute, to bring them down.

[01northernS4]

Because the air has just been sitting there heating up and there is no flow through the I/C system to cool them down. Takes a little bit of driving, maybe a minute, to bring them down.

Same thing happens to me but a minute of driving definitely doesn't do it... 5+ and then once it sits off it heats right back up again... have to literally let it sit overnight or like 4 hours plus... strange.

- - - Updated - - -

^^ Thanks, but why would there be say 10 or 15C difference of the two when the car is sitting with engine off (after a long drive)?

My IATs look normal-ish when driving (below 60C most of the time) but when I check the IATs after the engine is off for 20 min, the IATs go up to 70+C. I bled the SC yesterday (thanks TC), but am not sure why IATs creep up 20-30C when engine is off.

when you bled was there any air in the system?

[Waffles_s4]

Same thing happens to me but a minute of driving definitely doesn't do it... 5+ and then once it sits off it heats right back up again... have to literally let it sit overnight or like 4 hours plus... strange.

- - - Updated - - -



when you bled was there any air in the system?

Hard to tell because you have to have the engine running, so just do it and that way u will be sure its bled properly.

[theweebabyseamus]

Same thing happens to me but a minute of driving definitely doesn't do it... 5+ and then once it sits off it heats right back up again... have to literally let it sit overnight or like 4 hours plus... strange.

- - - Updated - - -



when you bled was there any air in the system?

If I fired the car up and got a constant air source and started at 50*c I imagine Id be under 40* within a minute assuming not like 100*F ambient. 95% water, 5% Purple Ice.

[djn876]

It's going to heat soak like that any time you drive and turn the car off and let it sit. Until the car is fully cooled down it's going to be hot when you start it. Drive it and it's going to come down to normal. If it doesn't come down when you drive it there is a problem, otherwise I guess I don't really understand what the question is.

When you turn the engine off, there is no flow through the IC and all of the engine heat starts baking everything, the SC and coolers absorb a bunch of heat, and passes that to the air that's just sitting in there, or any new air coming in (which isn't a lot at idle). Until you drive, it can't really reject that heat well.

[Waffles_s4]

These cars need a fan for the sc intercooler, but space is very limited for that

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[01northernS4]

These cars need a fan for the sc intercooler, but space is very limited for that

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+1... surprised nobody has come up with a solution... like turbo timers and fans that run after the car is off... anybody?

[theweebabyseamus]

You’d never be able to actually cool off the s/c itself enough to matter.

[JoedreddUK]

How accurate is OBD fusion on reading IATs? Looking for alternatives rather than a P3 gauge

[Rodizzle]

How accurate is OBD fusion on reading IATs? Looking for alternatives rather than a P3 gauge

Same reading . Reads of the same parameters .
The issue is when user are trying to read “boost” , most of the devices read of “request” instead of “actual” .


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[Allan691]

Same reading . Reads of the same parameters .

Is the P3 IAT reading pre or post?

[TC_S4]

Same reading . Reads of the same parameters .
The issue is when user are trying to read “boost” , most of the devices read of “request” instead of “actual” .


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OBDfusion IAT readings seems pretty accurate when I did some comparaison with Vagcom. As for the boost reading I believe it actual readings. The only complaint I have with OBDfusion is the refresh rate for the logs are too slow, you lose some infos. Example my rev limiter is at 7200rpm, it shifts just little before like 7100rpm. In my logs I only see 6759 @ 14.14 psi. Next data is 5985 rpm @ 15.76 psi. I am missing the data logs when it shifts at 7k rpm when boost should be ~16psi.

[Rodizzle]

Is the P3 IAT reading pre or post?

Post


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[Waffles_s4]

OBDfusion IAT readings seems pretty accurate when I did some comparaison with Vagcom. As for the boost reading I believe it actual readings. The only complaint I have with OBDfusion is the refresh rate for the logs are too slow, you lose some infos. Example my rev limiter is at 7200rpm, it shifts just little before like 7100rpm. In my logs I only see 6759 @ 14.14 psi. Next data is 5985 rpm @ 15.76 psi. I am missing the data logs when it shifts at 7k rpm when boost should be ~16psi.

Could be limitations of bluetooth, and the processing power of the phone you are using.

[unaimed1337]

I'm just dumbfounded by the amount of misconceptions and bad solutions here. This issue is not limited to SC cars, virtually every car will heatsoak and it's not because of the temperature of the coolant in the SC.
Adding fan to the SC intercooler makes so little sense that I think that whoever suggested it does not really understand the issue at all in the first place. You don't have any coolant flow, it doesn't matter at all, the heatsoak comes from the lack of air flow, coolant flow, and a giant metal block called engine.
You would literally have to have fan powerful enough to drop down the temperature of the whole engine compartment, which I believe would have to be bigger than the engine compartment itself.

Could be limitations of bluetooth, and the processing power of the phone you are using.

I don't think there is a phone on the market that has bluetooth but doesn't have enough processing power to process up to 100 PIDs per second, which IIRC is almost the max throughtput OBD2 receivers can read. And I'm talking about 10 year old nokias here too.
Torque allows you to enter high speed data mode or something like that though it doesn't work on all receivers. You could perhaps try looking for similar option in OBDFusion.

[Waffles_s4]

And do you think your phone is doing nothing else while it's logging your Bluetooth data?

Logging data via Bluetooth and a cell phone is just not the way to go. As soon as the phone's cpu is 100%, you are missing logging data, without you even realizing it.

Just hook up any app via Bluetooth and rev your engine, see how long it takes to reflect the Rpm on your phone. It's nowhere near real time, and that could be because of lack of cpu ressources on the phone and/or the Bluetooth protocol used.

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[theweebabyseamus]

I'm just dumbfounded by the amount of misconceptions and bad solutions here. This issue is not limited to SC cars, virtually every car will heatsoak and it's not because of the temperature of the coolant in the SC.
Adding fan to the SC intercooler makes so little sense that I think that whoever suggested it does not really understand the issue at all in the first place. You don't have any coolant flow, it doesn't matter at all, the heatsoak comes from the lack of air flow, coolant flow, and a giant metal block called engine.
You would literally have to have fan powerful enough to drop down the temperature of the whole engine compartment, which I believe would have to be bigger than the engine compartment itself.

I don't think there is a phone on the market that has bluetooth but doesn't have enough processing power to process up to 100 PIDs per second, which IIRC is almost the max throughtput OBD2 receivers can read. And I'm talking about 10 year old nokias here too.
Torque allows you to enter high speed data mode or something like that though it doesn't work on all receivers. You could perhaps try looking for similar option in OBDFusion.

I’m kind of wondering the same thing about your post...it doesn’t seem like you understand how the s/c loop works.

Anywho, the fans should work for the drag strip IAT issue as almost all (I think it probably IS all) tunes alter the s/c coolant pump dynamics in multiple ways, one being the use of coolant flow at idle. In addition, anybody with the cooling pump mod would have 100% cooling pump output as long as the cars running and some times with it off. So essentially with the fans on and car idling, you’d have external air being drawn through the heat exchanger, same as you would when the car is moving. Would it be as effective as driving along at 70 mph at neutral throttle? Of course not, but it should be better.

The part that’s most confusing is that is has been effective on other s/c platforms so why you’d think it wouldn’t work on ours is beyond me.

[Waffles_s4]

If the ambient temp is low, and u have a fan on the IC, while the coolant pump is running for 5 minutes after you turn off the car, yes it will have a positive effect

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[unaimed1337]

I’m kind of wondering the same thing about your post...it doesn’t seem like you understand how the s/c loop works.

Anywho, the fans should work for the drag strip IAT issue as almost all (I think it probably IS all) tunes alter the s/c coolant pump dynamics in multiple ways, one being the use of coolant flow at idle. In addition, anybody with the cooling pump mod would have 100% cooling pump output as long as the cars running and some times with it off. So essentially with the fans on and car idling, you’d have external air being drawn through the heat exchanger, same as you would when the car is moving. Would it be as effective as driving along at 70 mph at neutral throttle? Of course not, but it should be better.

The part that’s most confusing is that is has been effective on other s/c platforms so why you’d think it wouldn’t work on ours is beyond me.

You are talking about fully circulating car with presumable AC on and heater at full blast. Of course it makes a difference, however if the car is turned off, what difference would the pump and fan for the SC heat exchanger make?
Don't you see it just doesn't make any sense? How long do you want the fan and pump to run? 10 minutes? Then it's gonna still heatsoak after 15 minutes etc. To stop the heatsoak you would essentially have to equalize the temperatures through the engine compartment.
The whole idea just doesn't make any sense, unless you always shut the engine off for 10 minutes, it's a pointless exercise.

Just hook up any app via Bluetooth and rev your engine, see how long it takes to reflect the Rpm on your phone. It's nowhere near real time, and that could be because of lack of cpu ressources on the phone and/or the Bluetooth protocol used.

You obviously have no idea what you are talking about, first of all please read how actually OBD2 works from the programming side (hint: it's a querying protocol). And then finish it off with how for instance Android handles bluetooth and how much delay is inserted by the OS itself (there are couple interesting benchmarks for bluetooth audio).

If the ambient temp is low, and u have a fan on the IC, while the coolant pump is running for 5 minutes after you turn off the car, yes it will have a positive effect

Yes, for 5 minutes, after that it will still heatsoak away.

[bhvrdr]

You are talking about fully circulating car with presumable AC on and heater at full blast. Of course it makes a difference, however if the car is turned off, what difference would the pump and fan for the SC heat exchanger make?
Don't you see it just doesn't make any sense? How long do you want the fan and pump to run? 10 minutes? Then it's gonna still heatsoak after 15 minutes etc. To stop the heatsoak you would essentially have to equalize the temperatures through the engine compartment.
The whole idea just doesn't make any sense, unless you always shut the engine off for 10 minutes, it's a pointless exercise.

You obviously have no idea what you are talking about, first of all please read how actually OBD2 works from the programming side (hint: it's a querying protocol). And then finish it off with how for instance Android handles bluetooth and how much delay is inserted by the OS itself (there are couple interesting benchmarks for bluetooth audio).

Yes, for 5 minutes, after that it will still heatsoak away.

The capture rate for these free bluetooth apps are crap compared to vcds which is itself crap compared to professional dataloggers.

[Rodizzle]

The capture rate for these free bluetooth apps are crap compared to vcds which is itself crap compared to professional dataloggers.

Agreed


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[Waffles_s4]

You are talking about fully circulating car with presumable AC on and heater at full blast. Of course it makes a difference, however if the car is turned off, what difference would the pump and fan for the SC heat exchanger make?
Don't you see it just doesn't make any sense? How long do you want the fan and pump to run? 10 minutes? Then it's gonna still heatsoak after 15 minutes etc. To stop the heatsoak you would essentially have to equalize the temperatures through the engine compartment.
The whole idea just doesn't make any sense, unless you always shut the engine off for 10 minutes, it's a pointless exercise.

You obviously have no idea what you are talking about, first of all please read how actually OBD2 works from the programming side (hint: it's a querying protocol). And then finish it off with how for instance Android handles bluetooth and how much delay is inserted by the OS itself (there are couple interesting benchmarks for bluetooth audio).

Yes, for 5 minutes, after that it will still heatsoak away.

Urgh, the OS`s load, in terms of ressources, is directly related to the CPU power (and memory available). Run 2 OSs, one with a weak CPU, it will consistenly run at 90-100% of usage, where as, if you run it on a powerful CPU, with the exact same settings and configuration, it might run at 5% or less. When your CPU is running above 90%, it automatically start to drop packets. Add to that the BT protocol limitations, the ppor design of smartphone apps, and the fact that these phones are doing many more things than just capture your data logs for your car, and you end up missing a lot of results.

If you want proper logs, use a powerful laptop, with a professional interface/application, which are all purely dedicated to logging with absolutely the bare min running in the background.

Am gonna say it again: if ur using a phone, ur doing it wrong.

[Waffles_s4]

You are talking about fully circulating car with presumable AC on and heater at full blast. Of course it makes a difference, however if the car is turned off, what difference would the pump and fan for the SC heat exchanger make?
Don't you see it just doesn't make any sense? How long do you want the fan and pump to run? 10 minutes? Then it's gonna still heatsoak after 15 minutes etc. To stop the heatsoak you would essentially have to equalize the temperatures through the engine compartment.
The whole idea just doesn't make any sense, unless you always shut the engine off for 10 minutes, it's a pointless exercise.

You obviously have no idea what you are talking about, first of all please read how actually OBD2 works from the programming side (hint: it's a querying protocol). And then finish it off with how for instance Android handles bluetooth and how much delay is inserted by the OS itself (there are couple interesting benchmarks for bluetooth audio).

Yes, for 5 minutes, after that it will still heatsoak away.

The 5 min will help a lot if the car is sitting in traffic, or constant stop and go traffic. Also, if the car heat soaks at 80C (without the fan), versus 70C (with a fan hitting the IC), well I rather have it at 70C so it cools down in 1-2 hours versus a lot longer. There are always advantages to always run IATs as low as possible, or to decrease the amount of heat as much as possible.

[unaimed1337]

Urgh, the OS`s load, in terms of ressources, is directly related to the CPU power (and memory available). Run 2 OSs, one with a weak CPU, it will consistenly run at 90-100% of usage, where as, if you run it on a powerful CPU, with the exact same settings and configuration, it might run at 5% or less. When your CPU is running above 90%, it automatically start to drop packets. Add to that the BT protocol limitations, the ppor design of smartphone apps, and the fact that these phones are doing many more things than just capture your data logs for your car, and you end up missing a lot of results.

If you want proper logs, use a powerful laptop, with a professional interface/application, which are all purely dedicated to logging with absolutely the bare min running in the background.

Am gonna say it again: if ur using a phone, ur doing it wrong.

You are, again, incorrect about the load, please look at how linux calculates load for instance.
What you say might've made sense 10 years ago in the era of single core single threaded CPU's, but is completely incorrect given modern architectures. What does it even mean to run 90% CPU? Is it 9 out of 10 cores running at 100%, or 10 cores running at 90%?
Wheter it drops the packets or not is entirely up to the OS scheduler, application priority, etc.

[Waffles_s4]

You are, again, incorrect about the load, please look at how linux calculates load for instance.
What you say might've made sense 10 years ago in the era of single core single threaded CPU's, but is completely incorrect given modern architectures. What does it even mean to run 90% CPU? Is it 9 out of 10 cores running at 100%, or 10 cores running at 90%?
Wheter it drops the packets or not is entirely up to the OS scheduler, application priority, etc.

Sorry dude, you are completely wrong. 90% would be for all cores, and threads, which means the entire physical cpu. Packets start dropping at the network interface level when the cpu is at 90% or more. This is true for any device, including routers, firewalls, desktops, and even more for smartphones. When the packet arrives, and the cpu is at 100%, and its not even capable of processing it, let alone putting in memory for the OS to use it, it will be dropped at the interface, meaning, before it hits the cpu and then the OS. The packet drop will be random, not sequential, until the cpu is able to process packets. At this point, u might have packets at the interface buffer, but smartphones have veryyyy limited or no buffer at all for their interfaces. They are not built for that kind of requirements.

This has nothing to do with which os is used in the background. Scheduling is for process prioritization, scheduling has nothing to do with packets dropping when the cpu is over loaded.

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[unaimed1337]

Sorry dude, you are completely wrong. 90% would be for all cores, and threads, which means the entire physical cpu. Packets start dropping at the network interface level when the cpu is at 90% or more. This is true for any device, including routers, firewalls, desktops, and even more for smartphones. When the packet arrives, and the cpu is at 100%, and its not even capable of processing it, let alone putting in memory for the OS to use it, it will be dropped at the interface, meaning, before it hits the cpu and then the OS. The packet drop will be random, not sequential, until the cpu is able to process packets. At this point, u might have packets at the interface buffer, but smartphones have veryyyy limited or no buffer at all for their interfaces. They are not built for that kind of requirements.

This has nothing to do with which os is used in the background. Scheduling is for process prioritization, scheduling has nothing to do with packets dropping when the cpu is over loaded.

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https://unix.stackexchange.com/quest...d-in-this-case
We can agree to disagree, I'm not here to educate you about the workings of a modern architecture, be it CPU or OS.

[Waffles_s4]

Besides, any serious logging with wireless devices, be it BT, or WiFi, or lte is completely inaccurate if u want millisecond based reliable data logging. Just not the right way to do it.

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[unaimed1337]

Besides, any serious logging with wireless devices, be it BT, or WiFi, or lte is completely inaccurate if u want millisecond based reliable data logging. Just not the right way to do it.

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No questions there, you are completely correct in this statement.

[Waffles_s4]

https://unix.stackexchange.com/quest...d-in-this-case
We can agree to disagree, I'm not here to educate you about the workings of a modern architecture, be it CPU or OS.

I used to do this stuff for a living, I don't rely on some random posts on stackoverflow or stackwhatever to tell you what really happens in real production environments and why exactly they happen

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[Waffles_s4]

https://unix.stackexchange.com/quest...d-in-this-case
We can agree to disagree, I'm not here to educate you about the workings of a modern architecture, be it CPU or OS.

It's simple. If a packet never reaches the cpu, and therefore the os, and therefore the scheduling of the os, how is it supposed to process it for scheduling? It cannot.

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[unaimed1337]

It's simple. If a packet never reaches the cpu, and therefore the os, and therefore the scheduling of the os, how is it supposed to process it for scheduling? It cannot.

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It's even simpler, if that happens it's either a massive scheduler fuckup that should be filed as a bug report, or completely bonkers process priority/niceness, which again, won't really happen in a mobile phone under regular usage circumstances.
What you're saying could actually drop phone calls (even emergency ones) which is an obvious mistake from user end perspective, which is exactly why noone could afford it to happen.
Anyways, I'm done with this discussion, if you want to continue, please do it via private messages. Otherwise, we'll sidetrack an actual discussion here.

[Waffles_s4]

Sure let's drop it and be back to the subject. No point to argue. If u wanna know more PM me for more info on the why, and what happens when ur phone is frozen and cannot accept any phone calls :)

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[theweebabyseamus]

You are talking about fully circulating car with presumable AC on and heater at full blast. Of course it makes a difference, however if the car is turned off, what difference would the pump and fan for the SC heat exchanger make?
Don't you see it just doesn't make any sense? How long do you want the fan and pump to run? 10 minutes? Then it's gonna still heatsoak after 15 minutes etc. To stop the heatsoak you would essentially have to equalize the temperatures through the engine compartment.
The whole idea just doesn't make any sense, unless you always shut the engine off for 10 minutes, it's a pointless exercise.

I’m not sure why you’d think the car sits, off? Literally the whole discussion, aside from Waffles input, has been about bringing down IATs during the initial section of the drag strip. So you see you’re about 5 cars out in staging and you fire up your car to move it up a spot and leave it running, with the pump running on it’s own to circulate coolant and you turn the fan on to imitate to some extent, regular driving and airflow across the heat exchanger. It’s such a proven and common concept that I feel like I’m being trolled.

[Morritse]

[unaimed1337]

I’m not sure why you’d think the car sits, off? Literally the whole discussion, aside from Waffles input, has been about bringing down IATs during the initial section of the drag strip. So you see you’re about 5 cars out in staging and you fire up your car to move it up a spot and leave it running, with the pump running on it’s own to circulate coolant and you turn the fan on to imitate to some extent, regular driving and airflow across the heat exchanger. It’s such a proven and common concept that I feel like I’m being trolled.

What...? The OP literally asks about the car sitting OFF and creates a topic about the car heatsoaking while being OFF and then you tell me that it's about a dragstrip. Yes, turning the car on with heaters on full blast and pump on 100 and AC to trigger the fan is an obvious way to bring IAT and ECT down, I'm not questioning that.
The only post that mentions dragstrip is yours, and it's in response to mine, so please tell me how this has been about the dragstrip the whole time when literally the very first post is about the car heatsoaking without the engine running.