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Example of Z06 track use reduced power problem.
2016 Z06, FE7, M7. GM auxiliary radiator and DeWitts Gen 2 radiator.
Fuel 98 octane unleaded. Engine stock. Ambient temp 77 degrees.
5 minutes of track time coolant 214, oil 248, boost 12.1 psi, IAT2 91 degrees, manifold temp 235 degrees, A/F commanded 10.45 (cat over temp protection), total advance 11 degrees, IAT retard -14.7 degrees, coolant retard -.3 degrees, knock retard -1.67 degrees, 16.67 of timing retard due to temp and spark knock. Power reduction was very noticeable. After 15 minutes engine would not accelerate beyond 5000 rpm at full throttle. After a cool down lap engine would accelerate to red line for a few laps and then have reduced power again. Can't wait till summer when ambient is 90+.
Another log at 70 degrees ambient. Timing reduced to 9 degrees!
Intercooler coolant system is full and pump is working. GM claims IAT2 is the air temp going into the cylinders and manifold air temp is calculated based on IAT, water temp, and who knows what. IAT retard is based on calculated manifold air temp not IAT2.
Maybe the intercooler pump isn't running. Look for a big bubble in the reservoir too, something feels like it's amiss with the intercooler circuit to me if you're getting into reduce power that easily.
In keeping my timing theory, once it gets into timing retard that heats up the motor which pushes it further into timing retard, and so on.
But are the snapshots after the fact? In your snapshot the IAT2 is only 90-100 degrees, which shouldn't be causing much timing retard at all. Since you've got 98 octane I wouldn't expect you to be detonating with the stock tune.
The one gauge, if I'm reading it right, seems to indicate IAT2 got hot during the run, which is why you got retard I think.
IAT retard is based on calculated manifold air temp not IAT2.
I'm no expert but that seems backwards. IAT2 is what the combustion process sees, so other than startup, I thought IAT1 was largely ignored. I'm not saying you're wrong, but... I think you might be.
Second log IAT2 started out high due to sitting in pit lane lane idling. IAT2 temp lowered to 100 degrees once car was moving and had airflow through he intercooler radiator. This test was done using second and third gear running to red line in each gear at full throttle. RPM was above 4500 during the test to have a maximum load on the engine.
The table for IAT retard maps to the calculated manifold temp and not the actual IAT2 temp.
With the stock radiator and the GM auxiliary radiator and 93 octane pump gas the water temp would climb to 240 and the oil temp would climb to 290 degrees at 88 ambient last summer during track use which caused reduced power. So over the winter I added the DeWitts radiator thinking it would help the problem. Did not help. Water temps are 220 and oil temps are 260 at 80 degrees ambient. Problem is IAT temps inside the supercharger. Not sure if the 2017 supercharger upgrades helped but waiting to see if GM has a upgrade kit for 2015 & 2016 models. If some one shows up at our local track with a 2017 a would data log it to see if the IAT temps are reduced.
I dunno... I still think that table is IAT2 even though it just says IAT. After all, under what conditions would you have 275F ambient air? Just a hunch, not an expert.
Intercooler coolant system is full and pump is working....
I agree with DAVE396LT1 - it sounds like an intercooler pump problem to me.
I'm sure you've probably seen this thread below - it has to do with an exactly 3 minute shutdown of the intercooler pump when it cavitates, resulting a power loss for those 3 minutes.
There are no lights, codes, or anything else telling you of a problem, just a loss of power for 3 minutes.
You may think the intercooler coolant is full, but if there's a big enough bubble of air in the reservoir, or air otherwise in the system, you may need to do a vacuum refill of the system to make sure there is only a small bubble in that reservoir tank to keep the pump from cavitating. Take a look at the thread below:
I have twice now had a cracked catalytic converter that resulted in symptoms similar to what you describe once you run the car hard on track. In one case the car world barely rev at all and was limited to 4000 rpm. Cooling the car of made no difference unless you let it sit overnight.
In both cases I couldn't see the crack but you could hear the tick tick tick under the car.
02-26-2017, 01:16 PM
Z06 track use reduced power
