CHT sensor extension, Curious, does it work? Who uses one? Options

[malcolm2]

I want to cover all my bases here. I have purchased the new GB CHT sensor from 914Rubber to try.

So, I think I will buy a spacer from Brad Mayeur to have the option. From what he says it should:

"Porsche 914/4 Cylinder Head Temperature Sensor Extension.

This little device slows down the heating of the sensor and improves warm up drivability."

I do have "warm up drivability" problems = Low idle RPM until the VDO CHT hits about 250*F. So it seems like my problems don't need the warm up to slow down, it needs to SPEED UP. (IMG:style_emoticons/default/WTF.gif)

914LTD.com





Also found on RATWELL (scroll down to WORKAROUNDS)http://www.ratwell.com/technical/TempSensorII.html#parts

[pbanders]

OK, I have one of these and have been using it for a while. It definitely does help keep the car richer for longer during warm-up, and helps keep the idle good even after the AAR has closed and the car is still warming up. That's the good part. The bad part is that when you stop the engine, and go into Target for 30 minutes, it causes the CHT to cool off faster than if it were directly connected to the head. Since D-Jet 914's already have a hot start problem due to the differential cooling of the aluminum heads as compared to the iron cylinder sleeves (making the mixture too rich), this additional cooling makes it even worse. So you're trading one driveability problem for another.

The "solution" (which doesn't exist) is to have a properly-curved CHT that's directly attached to the iron cylinder sleeve. Or, maybe some other clever thing. IMO, it's just something we live with owning a 45-year-old car. I'm on the fence about taking it out the next time I have a chance. Fact is any time I drive the car, it's got to go through the warm-up phase, and this spacer does help, whereas I don't always take a 15-30 minute break on every drive, so I'll probably keep it installed.

BTW, when you have the "rich hot-start" problem, the solution is more air without more fuel. Here's what I do: with the key off, open the throttle about 1/4 to 1/3, then start the car. You don't want to turn the key and press the throttle down, because the "accelerator pump" action of the TPS will dump even more gas in. Immediately back off the throttle to keep the revs down when it starts. The additional air from the open throttle will start the car quickly, and the slight fouling of the plugs from the extra fuel will go away rapidly as you drive.