Hunting idle, Pretty sure its the head temp sendor Options

[VaccaRabite]

Caveat: I'm using custom fuel injection (Microsquirt)

So this weekend my idle started hunting. I was pretty sure I had sprung a leak somewhere that was opening and closing a miniscule amount while the car vibrated at idle.

My idle would go from 1000 RPM (where I have it set) to about 1900 RPM for a few seconds and then settle back down again. Whatever, drove the car for 300 miles anyway. Only time when it became an issue was at stop lights and trying to get through the free bridge traffic jam between NJ and PA - and then it was just an added annoyance.

When I got home I did not find anything obviously wrong. I plugged my laptop in to see if my IAC had gone out of compliance. It was fine but I noted my "coolant" temps were all over the place.

Coolant sensor for me is the stock location head temp sensor, plugged into my ECU.

Are these things known for failing? Mine was giving readings with a 100+ degree swings every few seconds (I'm guessing cutting out), and my idle air valve was opening and closing trying to keep up, hence the idle hunting.

Zach

[VaccaRabite]

I bought one of the DubShop units.

I thought I was using the stock head temp sensor, but it appears to be one that has been modified (and I now remember Mark saying that he had made several modified ones). Its a 2wire unit that has been potted into the stock sensor housing.

I'm going to just pull it and replace it with the DubShop sensor when I have a spare moment. If the sensor is to blame (as it seems to be) it should be a quick fix. If not, I'll get deeper into it later.

Not going to lie, I've been busier lately than a stump tailed cow in fly season. Maybe next week I'll have time. Work. Cubs. Boy Scouts. Kids music lessons. and trying to get the bus repainted before it gets too cold to do so... Too busy.

[JamesM]

I bought one of the DubShop units.

I thought I was using the stock head temp sensor, but it appears to be one that has been modified (and I now remember Mark saying that he had made several modified ones). Its a 2wire unit that has been potted into the stock sensor housing.

I'm going to just pull it and replace it with the DubShop sensor when I have a spare moment. If the sensor is to blame (as it seems to be) it should be a quick fix. If not, I'll get deeper into it later.

Not going to lie, I've been busier lately than a stump tailed cow in fly season. Maybe next week I'll have time. Work. Cubs. Boy Scouts. Kids music lessons. and trying to get the bus repainted before it gets too cold to do so... Too busy.

Not sure what Mark was using in his sensors but if they had a custom curve you may need to change the sensor calibration table back to stock on the MS when using marios sensor.

I just use one of his standard sensors (not the larger type 4 sensor) and attach it with an engine tin screw. Way easier then trying to get to the stock sensor location.