IAT 2 temperature check - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

newz · 04-25-2019, 12:52 AM

Is there a way to check the iat2 temp using a SCTx4 hand held tuner and a lap top ? I us the DeRIVE software from SCT on the laptop.

I can read the temp fine on the AEROFORCE gauge?

Thanks for any info from the forum members.

Shodown · 04-29-2019, 08:37 PM

Great question. I was asking that myself last night. I am not sure if it's reading IAT1 or IAT2. I assume IAT1. I wish it would read boost too.

I just did a few datalogs of the IAT with my SCT X4 on my way to work and on my way home today to see how the car is performing before I install a Roto Fab coolant reservoir and Water Wetter. I want to see what the difference will be.

RobZL1 · 04-29-2019, 09:15 PM

In my experience, I was never able to get the x4 to read iat2. It only read iat1.

CAM....ZL1 · 04-29-2019, 09:38 PM

Quote:

Originally Posted by Shodown

Great question. I was asking that myself last night. I am not sure if it's reading IAT1 or IAT2. I assume IAT1. I wish it would read boost too.

I just did a few datalogs of the IAT with my SCT X4 on my way to work and on my way home today to see how the car is performing before I install a Roto Fab coolant reservoir and Water Wetter. I want to see what the difference will be.

SCT4 does read boost, it is in absolute manifold pressure. It reads it in KPA, you just use a conversion app to get psi

Shodown · 04-29-2019, 10:25 PM

Quote:

Originally Posted by CAM....ZL1

SCT4 does read boost, it is in absolute manifold pressure. It reads it in KPA, you just use a conversion app to get psi

Awesome, good to know. Thanks!!

It also logs everything in Celsius which is also annoying to have to convert. The reader can be changed to Fahrenheit but I cant get Live Link to display it in the log.

newz · 04-30-2019, 11:46 PM

Thanks every body for the info. I checked with Ted at JANNETTY MOTORSPORTS and he said SCTx4 Does not read IAT2. I have been logging Ignition Timing Advance cylinder #1 along with throttle position sensor number 1 and RPM. All I have seen so far is that when I go full throttle the timing advance goes from 40 degrees to 11 degrees instantly.This timing drop may be related to air trapped in the intercooler. I have the car on RACE RAMPS now and will bleed at the top of the intercooler tomorrow. The IAT1 temp actually drops a little when going to full throttle. I may find a gently used :-) HP device to log the IAT2 temps. You can log the IAT2 temp on the AEROFORCE gauge but I don't believe the value can be exported to a log that can be imported into LiveWire software to be compared to SCTx4 values.

RobZL1 · 05-01-2019, 11:26 AM

The timing is dropping because your g/cyl went up when you went WOT. It's supposed to do that. Not related to IAT2.

newz · 05-01-2019, 11:26 PM

RobZL1 Dynamic Cylinder Charge what you are referring to as part of what caused timing to drop so far ? I have only read about rising IAT2 values as being the reason for the timing to drop quickly .

RobZL1 · 05-02-2019, 10:44 AM

Timing is backed out when heat and pressure increase in order to prevent detonation in the cylinder. I'm referring to the base spark advance mapping in the ECM that maps a timing advance to cylinder air mass and rpm. Other addition/subtraction/multiplication factors are present, too (such as for IAT's).

Ignoring those other additive factors, when you increase the airmass into a cylinder, the commanded timing becomes less advanced. This is to line up the maximum pressure wave of combustion with the appropriate point in the piston travel. At cruise, 40 degrees or more timing does the trick. When you whack the throttle open and throw a ton of air in the cylinder, you can't ignite the mixture anywhere near as early as you did when you were just cruising around or it will knock. This is because you have faster flame propagation due to the denser charge contained in the same volume. If you ignite it too early, you'll be pushing down on the piston as it's still coming upward in the bore (detonation/knock).

Basically, the drop in timing is expected/normal when you suddenly go to WOT. If you kept the spark advance at 40+, you'd be harming the engine. 11 degrees is within the normal range (mod dependent) when you go WOT somewhere in the middle of the rev range.

Now let's say your IAT2's were 160 degrees F when you went WOT. There's a spark map for that, too. It maps spark adder vs. IAT and cylinder air mass. As IAT's climb, spark is removed. Again, because increased heat and pressure require less spark advance (otherwise you'll reach your max pressure while the cylinder is still on the upstroke in the bore = detonation/knock). In a stock map, you'd be pulling a lot of timing at 160F (7+ degrees, depending on the multipliers that are also present).

Hope that helps explain it a bit. Dynamic Cylinder Charge may be what SCT calls it, I'm not sure. But HPTuners and EFILive call it Cylinder Air Mass.

EDIT- I was looking for a graph of spark advance for you since I don't have my tuning laptop right now, and I found this. It's got a graph and more explanation of the above.
https://www.camaro5.com/forums/showthread.php?t=205294

newz · 05-06-2019, 02:35 PM

Thanks for the good tutorial. The drop in timing related to engine speed I get. Did not know about the table that links engine speed to IAT2 temp. Thanks again

RobZL1 · 05-06-2019, 04:43 PM

No problem. Glad it made some sense.

To add detail for you, the IAT is linked to cylinder air mass, RPM, and ECT. The IAT/cylinder mass table has a value in it, which is then multiplied by a value from the IAT/RPM table and multiplied by another value from the IAT/ECT table. That final value is then subtracted from the base commanded spark.

So, in the 160F example- you could be at 4000rpm, 1.20g/cyl and 200F ECT and have 160F IAT2. Your spark due to increased IAT2 would then be something like: 20 base, minus 9*0.75*0.98 = 20-6.6 = 13.4

newz · 05-06-2019, 10:08 PM

RobZL1 the additional info is most welcome. Now I need to purchase something to be able to scan all the values with.

JANNETTYRACING · 05-07-2019, 09:38 AM

Quote:

Originally Posted by newz

RobZL1 the additional info is most welcome. Now I need to purchase something to be able to scan all the values with.

More and more HPtuners is making a huge comeback in the GM market and we are setting our customers up with Hptuners hardware.

It logs Ethanol content and IAT2 where SCT does not.

In livelink, I can usually tell from the timing commanded and actual that the IAT2 is pulling it to protect the engine though.

newz · 05-07-2019, 07:31 PM

Ted Thanks for the information. Man I wish I had half of your Knowledge on tuning :-) OK experience would probably help too.

04-29-2019, 09:15 PM	#3
RobZL1 fo'shizZL1 Drives: 2017 ZL1 Join Date: Aug 2017 Location: ATL Posts: 1,281	In my experience, I was never able to get the x4 to read iat2. It only read iat1. __________________ 2017 ZL1 M6 Black \| Maggie 2650 // 103TB // Big Gulp Past Rides- 2014 ZL1 M6 Red Hot \| Tons of mods 2004 CTS-V M6 Silver \| Many mods 1995 Corvette M6 Torch Red \| A few more mods 1992 Camaro M5 White \| A few mods

05-01-2019, 11:26 AM	#7
RobZL1 fo'shizZL1 Drives: 2017 ZL1 Join Date: Aug 2017 Location: ATL Posts: 1,281	The timing is dropping because your g/cyl went up when you went WOT. It's supposed to do that. Not related to IAT2. __________________ 2017 ZL1 M6 Black \| Maggie 2650 // 103TB // Big Gulp Past Rides- 2014 ZL1 M6 Red Hot \| Tons of mods 2004 CTS-V M6 Silver \| Many mods 1995 Corvette M6 Torch Red \| A few more mods 1992 Camaro M5 White \| A few mods

05-02-2019, 10:44 AM	#9
RobZL1 fo'shizZL1 Drives: 2017 ZL1 Join Date: Aug 2017 Location: ATL Posts: 1,281	Timing is backed out when heat and pressure increase in order to prevent detonation in the cylinder. I'm referring to the base spark advance mapping in the ECM that maps a timing advance to cylinder air mass and rpm. Other addition/subtraction/multiplication factors are present, too (such as for IAT's). Ignoring those other additive factors, when you increase the airmass into a cylinder, the commanded timing becomes less advanced. This is to line up the maximum pressure wave of combustion with the appropriate point in the piston travel. At cruise, 40 degrees or more timing does the trick. When you whack the throttle open and throw a ton of air in the cylinder, you can't ignite the mixture anywhere near as early as you did when you were just cruising around or it will knock. This is because you have faster flame propagation due to the denser charge contained in the same volume. If you ignite it too early, you'll be pushing down on the piston as it's still coming upward in the bore (detonation/knock). Basically, the drop in timing is expected/normal when you suddenly go to WOT. If you kept the spark advance at 40+, you'd be harming the engine. 11 degrees is within the normal range (mod dependent) when you go WOT somewhere in the middle of the rev range. Now let's say your IAT2's were 160 degrees F when you went WOT. There's a spark map for that, too. It maps spark adder vs. IAT and cylinder air mass. As IAT's climb, spark is removed. Again, because increased heat and pressure require less spark advance (otherwise you'll reach your max pressure while the cylinder is still on the upstroke in the bore = detonation/knock). In a stock map, you'd be pulling a lot of timing at 160F (7+ degrees, depending on the multipliers that are also present). Hope that helps explain it a bit. Dynamic Cylinder Charge may be what SCT calls it, I'm not sure. But HPTuners and EFILive call it Cylinder Air Mass. EDIT- I was looking for a graph of spark advance for you since I don't have my tuning laptop right now, and I found this. It's got a graph and more explanation of the above. https://www.camaro5.com/forums/showthread.php?t=205294 __________________ 2017 ZL1 M6 Black \| Maggie 2650 // 103TB // Big Gulp Past Rides- 2014 ZL1 M6 Red Hot \| Tons of mods 2004 CTS-V M6 Silver \| Many mods 1995 Corvette M6 Torch Red \| A few more mods 1992 Camaro M5 White \| A few mods

05-06-2019, 04:43 PM	#11
RobZL1 fo'shizZL1 Drives: 2017 ZL1 Join Date: Aug 2017 Location: ATL Posts: 1,281	No problem. Glad it made some sense. To add detail for you, the IAT is linked to cylinder air mass, RPM, and ECT. The IAT/cylinder mass table has a value in it, which is then multiplied by a value from the IAT/RPM table and multiplied by another value from the IAT/ECT table. That final value is then subtracted from the base commanded spark. So, in the 160F example- you could be at 4000rpm, 1.20g/cyl and 200F ECT and have 160F IAT2. Your spark due to increased IAT2 would then be something like: 20 base, minus 90.750.98 = 20-6.6 = 13.4 __________________ 2017 ZL1 M6 Black \| Maggie 2650 // 103TB // Big Gulp Past Rides- 2014 ZL1 M6 Red Hot \| Tons of mods 2004 CTS-V M6 Silver \| Many mods 1995 Corvette M6 Torch Red \| A few more mods 1992 Camaro M5 White \| A few mods

04-25-2019, 12:52 AM	#1
newz Drives: 2013 ZL1 Join Date: Dec 2017 Location: ohio Posts: 82	IAT 2 temperature check Is there a way to check the iat2 temp using a SCTx4 hand held tuner and a lap top ? I us the DeRIVE software from SCT on the laptop. I can read the temp fine on the AEROFORCE gauge? Thanks for any info from the forum members.

04-29-2019, 08:37 PM	#2
Shodown Drives: 2014 ZL1 Join Date: Jun 2009 Location: Tucson, AZ Posts: 314	Great question. I was asking that myself last night. I am not sure if it's reading IAT1 or IAT2. I assume IAT1. I wish it would read boost too. I just did a few datalogs of the IAT with my SCT X4 on my way to work and on my way home today to see how the car is performing before I install a Roto Fab coolant reservoir and Water Wetter. I want to see what the difference will be.

04-30-2019, 11:46 PM	#6
newz Drives: 2013 ZL1 Join Date: Dec 2017 Location: ohio Posts: 82	Thanks every body for the info. I checked with Ted at JANNETTY MOTORSPORTS and he said SCTx4 Does not read IAT2. I have been logging Ignition Timing Advance cylinder #1 along with throttle position sensor number 1 and RPM. All I have seen so far is that when I go full throttle the timing advance goes from 40 degrees to 11 degrees instantly.This timing drop may be related to air trapped in the intercooler. I have the car on RACE RAMPS now and will bleed at the top of the intercooler tomorrow. The IAT1 temp actually drops a little when going to full throttle. I may find a gently used :-) HP device to log the IAT2 temps. You can log the IAT2 temp on the AEROFORCE gauge but I don't believe the value can be exported to a log that can be imported into LiveWire software to be compared to SCTx4 values.

05-01-2019, 11:26 PM	#8
newz Drives: 2013 ZL1 Join Date: Dec 2017 Location: ohio Posts: 82	RobZL1 Dynamic Cylinder Charge what you are referring to as part of what caused timing to drop so far ? I have only read about rising IAT2 values as being the reason for the timing to drop quickly .

05-06-2019, 02:35 PM	#10
newz Drives: 2013 ZL1 Join Date: Dec 2017 Location: ohio Posts: 82	Thanks for the good tutorial. The drop in timing related to engine speed I get. Did not know about the table that links engine speed to IAT2 temp. Thanks again

05-06-2019, 10:08 PM	#12
newz Drives: 2013 ZL1 Join Date: Dec 2017 Location: ohio Posts: 82	RobZL1 the additional info is most welcome. Now I need to purchase something to be able to scan all the values with.

05-07-2019, 07:31 PM	#14
newz Drives: 2013 ZL1 Join Date: Dec 2017 Location: ohio Posts: 82	Ted Thanks for the information. Man I wish I had half of your Knowledge on tuning :-) OK experience would probably help too.