starting without glowplug in cylinder no. 1

[tungs10]

Hi,

We are doing a sort of research project. We want to outfit a 6L Powerstroke with a fiber optic pressure sensor in one of the cylinders. This sensor is connected to some electronics that is also connected to the buffered crankshaft position sensor signal that runs from the PCM to the FICM. This electronic system then logs data and can make a plot of pressure vs. volume called an indicator diagram. This is for fuels research.

So my question, what is the best procedure for starting the engine? I was thinking, start the engine with the glowplug in, get it hot. Swap out with the sensor while the engine is still hot. Then restart the engine and run the tests.
...or... just try and start with the sensor in. There will probably be some unburned fuel in the cylinder by the time it gets going and a bit smoke and soot and hope the sensor doesn't get fouled with soot.

The company that makes the sensor, Optrand has a patent for a glowplug with their sensor built in. But it was a development they never pursued. All they have is sensor that will fit into the glow plug port.

[2006PSDSD]

Easier to start with the cylinders warm, but may be harder to get the GP out. It will still start with only on GP out though. What are you trying to accomplish by having a sensor installed permanently? Just to keep an eye on compression?

[APEowner]

A fiber-optic pressure sensor works by optically measuring the deflection of a metal diaphragm. Since the optical part is isolated from the pressure vessel (in this case the combustion chamber) it should be pretty immune to soot.

If you're trying to get data during the warmup cycle (which, by the way, is extremely difficult to accurately reproduce) then you need to figure out a way to get both the sensor and the glow plug in the chamber. Otherwise I'd just stick it in there and live with the slight skip on cold start.

You'll want to come up with a test sequence that ensures that both the entire engine and that cylinder in particular are up to temp before you start gathering data. You might want to include monitoring cylinder contribution before gathering data in you test procedure.

[tungs10]

Thanks

I just want to get a feel for the difficulty of starting the engine in warm weather with one of the glowplugs off-line. (Won't be doing this in winter, thats for sure). I am not sure how much volume the glow plug tip occupies but if the sensor doesn't displace that volume, I should think it is going to reduce the compression ratio a bit on that cylinder.

[APEowner]

It'll start fine. It might skip a bit at first but it'll start.