Corvette LT4 really high IAT and MAT : 60-70 degrees above ambient air. Reason?

[djyankees31]

Every since I got the LT4 supercharger installed on my Z51, I've had super high IAT and MAT's.

I see others with IAT usually 10-15 degrees above ambient but I experience 60+ degree above ambient. This is just cruising around and not even tracking. When I run 70+ down interstate the temperature don't lower much either.

I've reinstalled the Halltech CAI and made sure everything was sealed. That help by 10 degrees as it was worse. Shop didn't install the sealing strip at air box opening and the round seal to tube was broken and only covering about half the tube.

Should the IAT's be running in the 10-20 degree range above ambient air?

Does this mean the air under the fender is getting to hot and not getting enough outside air?

Using a temperature gun, the intake tube is usually 130-160 degrees when i check it. Is that normal?

What should I check to determine the issue?

Please advice and much appreciated?

A log from last weekend is attached.

Thanks
Darryl

[TriPinTaZ]

Do you have the coolant line touching the MAF sensor by chance?

[djyankees31]

Do you have the coolant line touching the MAF sensor by chance?

It's not touching the sensor but the small line and a radiator hose is touching the air box and tube. I have tried wrapping with a heat wrap and placing a heat shield on the Halltech air box and tube. But that hasn't helped. It was installed this way by Weapon-X. I was wondering if the lines need to be moved or rerouted?

[TriPinTaZ]

It's not touching the sensor but the small line and a radiator hose is touching the air box and tube. I have tried wrapping with a heat wrap and placing a heat shield on the Halltech air box and tube. But that hasn't helped. It was installed this way by Weapon-X. I was wondering if the lines need to be moved or rerouted?

Unless its touching the MAF sensor, I don't see it being able to transfer enough heat with such a small contact area to affect intake temps. I assume the tuner didn't touch the IAT frequency calibration?

[djyankees31]

Unless its touching the MAF sensor, I don't see it being able to transfer enough heat with such a small contact area to affect intake temps. I assume the tuner didn't touch the IAT frequency calibration?

Just checked, the IAT Sensor calibration is the same as stock.

Is it possible that the air under the wheel well is getting that hot from an leak somewhere?

[paulsmithsr]

U need to use dsx tuning LT1 TO LT4 TMAP CONVERSION HARNESS and put your IAT / map in the back of the blower and use a z06 map/IAT sensor

LOOKED AT LOG and u are getting knock-- keep driving and motor will blow up sooner or later with knock
also throotle only opening 84% u need help with your tune

[djyankees31]

U need to use dsx tuning LT1 TO LT4 TMAP CONVERSION HARNESS and put your IAT / map in the back of the blower and use a z06 map/IAT sensor

LOOKED AT LOG and u are getting knock-- keep driving and motor will blow up sooner or later with knock
also throotle only opening 84% u need help with your tune

Weapon-X did the install and supplied the necessary harness's. I'm assuming everything should be correct as they pioneered the LT1 to LT4 conversion. I also paid for the various harness's. However, I wouldn't know by looking at it. Do you have a picture you can share of your harness setup so I can compare?

So is the IAT not pulled from the MAF sensor with the LT1 TO LT4 TMAP CONVERSION HARNESS?

As for the knocking, it's knocked the same or worse since picking up from Weapon-X. I was initially concerned by they have assured me many times that it's false knock. Even in the log attached, I'm running Boostane with 93 octane. So the octane should be 100+.

I thought the max Throttle Position SAE on Gen V was 84%. Do you get 100% for this PID?

[paulsmithsr]

Ok so it’s a z06 map and IAT so it reads in the back of the blower so that’s why your IAT-Reads higher it’s not in front of throttle body like a stock car - Who ever tuned car didn’t do it right With the knock and throttle not opening all the way’ I get 100% with my car and zero knock your (torque setting are off) and driver demand off

[littlefield]

I get 84% on mine , also. Actually 86. One of the other throttle, peddle or TPS PID?s will get to 100%.

[littlefield]

To mean anything the IAT (maybe more correctly IAT2) should be downstream of the inter cooler. How does the intercooler work? Air to air , air to water?

[djyankees31]

To mean anything the IAT (maybe more correctly IAT2) should be downstream of the inter cooler. How does the intercooler work? Air to air , air to water?

It has the factory LT4 intercooler tank and pump along with the Granatelli HX expansion tank. This is a nightmare to keep the air out properly. However, I am able to keep the pump from cavitation by using a method on Youtube to keep feeling with liquid until there is no excess air in the hoses. However, it's every other weekend and a pain is the as*.

There's so many conflicting information in this forum and corvetteforum on the IAT, IAT2, and MAT. I understand exactly MAT but still don't know for sure if IAT is in the MAF sensor or back of the supercharger and where is the IAT2 then.

Even my ambient air temps will increase by 20-30 degrees during a 30 minute drive. I thought ambient air would stay the same to match actual outside air temp. What would cause it to rise steadily too?

[littlefield]

Reading the How To/ Speed Density sticky at the top of this forum helped me understand the terminology. IAT is the temperature before the throttle, IAT2 is the temperature before the engine. On a NA car they’re the same thing, on a boosted engine not so much. On my Whipple a new IAT sensor is located downstream of the intercooler and a wiring harness is used to sense the temperature there rather than in the MAF. So in effect it is now IAT2 and there is no IAT. What’s MAT? The ambient air sensor on my truck is located on the front grill. It didn’t get put behind the intercooler, did it?

[paulsmithsr]

Ok basic stuff. Maf . Not mat Measures air coming in engine
IAT 1 is before Intake measures air temp on lt1 and lt4
IAT 2 after blower ;only on z06 lt4 measures air temp
On lt1 maf/map and IAT are together before throttle body
With lsxtuning (break out) takes IAT/ map from stock location and puts in back of blower
so reads higher IAT because is has heat (boost) on it - which is more accurate for boosted car ——the 3 bar z06 map sensor is both iat/ map

[littlefield]

I would guess the intercooler is not cooling properly. Still air in the system, pump not working properly, obstruction. If you can hear the pump cavitating either the level is really low, there's something blocking the suction or the coolant temperature is close to boiling.

[littlefield]

Did WeaponX change the thermostat? Whipple supplied a 160F thermostat. There's a place in the tune to change the mechanical thermostat setting.

[djyankees31]

littlefield, The current temp issues are not related to the water pump. I'm always monitoring and know if/when it stops based on a steady temperature increase for 3 minutes.

I did have the 160 thermostat installed and I've changed the mechanical thermostat setting too. However, WX didn't make the change. I've also changed the axis when the fans starts and the %.

thanks for your help!

[littlefield]

Was the pump running when you took the data?

[djyankees31]

Was the pump running when you took the data?

Yes, all the logging is with the pump working.

I have the pump working 99% of the time as I frequently check the system for air in the lines.

[littlefield]

Man, I don’t know. There is a cooling problem. Intercooler and engine are both too hot. Can’t imagine why the intercooler circulating pump should not operate all the time.

[ZBADESTZ]

If you are using a factory z06 intercooler pump take that off and install a C6 ZR1 intercooler pump....1 of the best flowing pumps....you can get a used 1 for like $250


I read somewhere in one of the corvetteforum threads that the stock pump would shut down for 3 minutes every now and them based on some calculations