[EMF Audio (McMedics)]

Did you do the tune before or after the modifications? One modification after the tune could be triggering it, particularly the downpipes. You might also check to see if the pipe between the air box and MAF is still connected and seated correctly.

 

[EMF Audio (McMedics)]

Quick update,
Car performance seems not consistent due to IAT sensor and its impact on the tune. Heat soak and high reading of IAT (Intake air temperature) caused power reduction and retarded ignition timing. The ambient was around 25c(77f) but the IAT reading was very high around 69c (156f) before making a pass in dragstrip! seems moving at low speed and setting idle in the lane for long time caused such power loss issue. However, checking different logs of WOT at 35C (95F) days seems to have some power loss as well due to the safety in tune (timing retards) and false positive high IAT temps due to heat soak of IAT.

I replicated the same scenario while driving ON STREET and tried to observe the IAT when cruising or when setting at idle, shutting off the car, starting, moving at low speed, etc. Conclusion is the higher outside/ambient temp is, the worse the situation it gets with heat soak. Driving at medium speed, will bring the IAT down but not so quickly and not close to the ambient at all and still IAT will read high temperature due to heat soak from engine bay, exhaust most probably, etc.

Thinking of possible solutions:

• Have anyone thought off relocation of the IAT sensor to a cooler place where it is less prone to heat soak? where is that IAT sensor located actually on 12c/650s?
• Try to insulate/wrap the exhaust manifold, sensors, radiator hoses, intercooler?
• Methanol injection (is it helpful to get the starting point of IAT lower? because if it like reading 70c then you sprayed meth, it will cool down, but still you lost power, and according to m-engineering, the tune read from low ignition table sue to high IAT reading) so not sure if this will help the situation from the base start.
• Adjust the tune not to retard timing until high IAT, but it seems not good idea if you get to that high temperature somehow and not pull the necessary timings
• Better control IAT via standalone ECU like syvecs as might the stock ECU is reducing power/torque because of different calculations/factors like highs temperature where it is not discovered/known by current tuners
• Any other idea to try?

Living in hot climate areas like 85f+ you will immediately lose power after first pull or after driving and reaching to the racing area unless if you race immediately after a cold start like drag race cars lol

Moving the AIT sensor to show a lower temperature to manipulate the tune is like closing your eyes while you get robbed. It doesn't make a good thing happen, it just masks the bad. The failsafes are there for a reason, to protect your engine from blowing up.
Yes, wrapping the exhaust will help with engine bay temps, possibly quite a bit if you do it right. Intercooler and other items you might try gold tape.
Meth injection WILL bring down temps but while idling it won't do much I suspect.
Adjusting the tuning is the same result as changing the temperature sensor location, bad.

The best thing you can do is NOT idle it, push it through lanes till you get to the line.

 

[EMF Audio (McMedics)]

Thanks for your support and taking this step by step with me in private, very informative. The idea not to fool and IAT to read colder air, it is actually the quite opposite where to find a solution for such sensor that enable it to read the actual/close to ambient temp or actual air temp before entering to engine.

Current issue shows (not specific to Mclarens) that IAT sensor is pro depending on its location, IAT design and material, engine bay temp, ambient temp, exhaust close to IAT, modification to car is that IAT sensor is prone to heat soak issues which causing incorrect reading of the actual air temp going to engine. The other issue I see on my car, once the sensor heat soaked , it will not cool off quickly to same 10 degree of ambient after long/normal cruising. I might be wrong thought, but at least this is my experience on my car in past weeks. I was monitoring the IAT readings with OBD/Torque app and it is really heat soaked close to grilled sensor lol, especially for short runs, stopping the car, riding again, etc. Outside temp now around 37c.

Pushing the car to the lane like a drag race car is not a good option for me, also I might do that for an ultimate pass/record. However if you are in competition, and you will have minimum 3 drag passes, you are done with this issue

Anyone have a picture of the IAT sensor or part# ?

Thank you

I'm traveling but I can show where it is later. Pushing the car may not be a great option but it's the best solution. There is a reason drag cars do it and it's not just fuel usage.