Logging LT4 (C7/Z06) IAT, IAT2, and manifold temp.
I am assuming manifold temp is air after the internal heat ex-changers in the super charger that is being fed to the cylinders, IAT2 is the temp sensor in the MAF, but what is IAT measuring?
There is a PID for ambient but it shows outside air temp. IAT reads above ambient, IAT2 read above IAT, and manifold temp reads 200+ degrees under full load.
Any ideas?
IAT is in the MAF, Manifold Air Temp is used in place of IAT2 on these cars. Don't use IAT2 pid.
Just because the scanner has pids, doesn't mean they are all correct for your car.
Is the IAT spark advance correction table using Manifold Temp PID?
yesOriginally Posted by wstaab
I have a 2017 C7 Z06. I'm confused as to which is right. It logs two Manifold Air temps and one IAT2. I hope the Manifold Air temp are not what the engine is seeing. Awfully hot after a short idle period. Ambient was only in the upper 70s today when I ran this. And two vehicle speeds?
Need the Fan controls badly so when in the staging lanes can run the fan to keep these temps down some.
Here's my file. No tranny tables???
Last edited by 8850; 01-17-2017 at 04:57 AM.
i don't think the 17s have TCM support yet. are you using the beta?
http://www.hptuners.com/forum/showth...ison-Supported!
Yes, using 3.5 beta.
Oh me! However this tranny shifts like lightning so as long as I'm happy with shift rpm then I don't see the need for tuning.
How about just making our Vehicle Controls functional! I need to be able to turn my fan on in the staging lanes and during a pass.
Need the CAN ID for manifold temp so I can add it to an AIM data logger.
Can anyone help?
HPTuners shows IAT2 at manifold temp in the calibration file. But it does not map correctly in the scanner. What does IAT2 map to in the scanner?
IAT2 is the true manifold temp. IAT1 is in the MAF. "Manifold air temp" is a calculated air temp that references IAT1,IAT2 and Ambient air temp.
That being the case Manifold Air Temp tells us nothing we can use for tuning or fixing a problem? Also you and Higgs seem to differ. Monitoring true manifold temp (IAT2) is important to monitor if that's the true manifold air temperature that the engine sees.
In any case mine gets really hot idling and need to get that fan running in the staging lanes!
The ECM uses MAT for the IAT Modifier table, not IAT2.
I scan what the ECM uses, not what feels good. Just because it's calculated doesn't mean it's bad.
Go scan your IAT1, IAT2, and MAT and compare it to IAT Timing Retard and see for yourself. Many times I see IAT2 cool off under boost and MAT rises and IAT Spark Retard also rises, the two follow each other.
I was logging IAT2 at first wondering why it was so cool but I was still getting IAT Reduction.....
In my personal car and every other LT4 I have logs for all reference IAT2 for the "IAT Spark Advance Correction" table. Timing reduction and or timing add correlate with the IAT table.
I have 100 ish logs from 40ish 15,16 and 17 LT4's.
Maybe your Mult1, 2, 3, and 4 Tables are modifying them without your knowledge.
Maybe they are but I am not the only one who has had the same observation.
Maybe there is a scanner issue.
I don't really know why but you're the first person I have seen say their IAT table matches IAT2 with 3.4/3.5 on the LT4s.
I also delete logs after I am done with them so I don't have 100. ;-)
Do you think it's correct that IAT2 shows a reduction in temps under full load yet tons of timing is pulled on hot road courses and the car basically shuts down? Seems counterintuitive to me.
I can cruise down the road logging IAT2 and MAT and IAT2 might say 100 and MAT will say 170 and the IAT Correction in the log matches the IAT table/modifiers in the tune at 170.
Last edited by Higgs Boson; 01-18-2017 at 04:50 PM.
2016 LT4 HPTuners log.
Ambient 70 degrees, IAT 77 degrees, IAT2 88 degrees, Manifold temp 174 degrees.
Cylinder air mass .35 grams, IAT advance -2.8 degrees.
IAT Spark Advance Correction table shows -2.8 degrees at 174.
So table is using manifold temp. Infrared temp gun shows supercharger much hotter than 88 degrees.
Don't beleive IAT2 is air temp after the heat ex-changers in the supercharger.
This pid also utilizes engine coolant temp to derive this value. GM knows that heat transfer from the engine will effect the inlet charge temp so engine coolant adds to the equation. If you let a car cool down to where measured IAT is cooled off but engine coolant is still up; manifold temp will still be high.
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Looks like you are mixing units on your temps Deg C and DegF. Ambient of 70 F, with to 77 at the intake make sense warming up, IAT2 of 88 C (190 F) sounds correct , for post intercooler temp. IAT1 (post compressor) would be about 100F warmer (140 C)
on our 2017 Camaro ZL1 with the scanner i log pid manifold air temp. if i disconnect the sensor the value will not change in the scanner so i think ist calculated. with GDS2 and MDI on the car sensor name is IAT3 and value go to -40 degree Celsius if i dissconect the sensor
there two manifold air pids. one is calculated and the other is intake air 3.
manifold air temp.PNG
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