I have a strange issue with my IAT. The car is running fine, but on the logs rather than a smooth-ish line, it's more like a saw tooth trace. And every now and then (rhythmically) the temp spikes down 4-5 degrees but just for a split second before coming back up again. The odd thing is the engine doesn't need to be running to get this to happen, just the ignition on.
So far I have checked the wiring. All earths are a healthy 0.2 Ohms and including the LC-1 Wideband Lambda are earthed at the same point. I've got a constant 4.950V at the TPS. I’ve shorted the IAT and TunerStudeo reads exactly 21 degrees. And today I fitted a new IAT, but it seems the same. The only odd thing is.... As is normal the TPS, IAT,CLT are earthed through the Microsquirt (pin 20); when checking earths to the chassis I get 0.2 ohms. But when I turn the ignition on that jumps to 4.2 ohms.
Is this normal? And should I be worried about it?
I have the car booked in for a rolling road session in a couple of weeks, so if it's going to be an issue I'd rather it's sorted before as it's £60 p/h there.
