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IAT sensors

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After watching a tutorial on IAT sensors I was wondering if i could run a couple things by you guys.

So this application applies to EFI Harley Davidson engine. (don't laugh):

On all fuel injected Harley engines, the IAT sensor is located after the throttle body on the intake manifold. For those of you not completely familiar with Harley intake manifolds, they are short 1-2 pipe designs located at the top Centre of the V on the engine block.

After reading/watching the effect heat soak and engine temp can cause abnormal readings from the IAT sensor, by brain started to run through several scenarios that are very typical of Harley engines.

So on a hot day (in NZ) when the motorcycle is idling at the traffic lights you can get misfires or erratic idle. Could this be the effect where the hot engine temp (and outside air temp) could be heating up the intake manifold and causing the IAT sensor to read incorrectly?

Remember: Harley engines are air cooled, so reply heavily on air flow past the cylinders for cooling (as well as fuel).

Another situation would be when the engine has been run for a bit on a hot day, turned off, then started a short time after that. From the time the engine has been shut down, to the time your turn it back on, the engine will actually hold (or sometimes momentarily increase) in temp due to a lack of fuel for additional cooling. This excess heat could end up soaking into the intake manifold and cause false readings?

Most (especially performance and aftermarket) Harley intake manifolds are made of alloy, a material prone to heat soak.

Do you think there could be some gains in engine efficiency, hot starts, performance from moving the standard IAT sensor to the air filter before the throttle body and away from the center of the engine?

Or am i just talking gaga?

Thanks in advance.


Hello Hadyn

it is common on Harleys I have seen to have this heat soak issue i often move them to the air cleaner or ambient temp position

Regards Ross