The subject of idiot-light-oriented simple 6 psi pressure switches + panel needle gauges masquerading as legitimate oil pressure gauge systems on '99 and earlier Cobras has been pretty well hashed out on other forums (BON, Corral), but I haven't seen much here on the L equivalent (which I understand to have similar non-function). Also, to date I haven't seen an aftermarket fix for this on any Cobra forum and I suspect the same reason has prevented much progress on a fix/upgrade for the L gauge... the computer has digital control of the gauge and the surgery required to get that straightened out likely involves mucking with the microcode to either a) get the CPU to ignore what you are doing with a rewired analog setup, or b) get the CPU to honor your rewired analog setup. Has anyone fussed with their L and made a working gauge out of the factory one? Failing that, is there a decent aftermarket kit that looks good, i.e., looks like it belongs in the cabin? TIA.

-tvw


[This message has been edited by tvw (edited 05-09-2000).]

 

I posted this question about 6 months ago, got no answers at all. I'd really like a real oil pressure gauge, not an idiot light with a stick on it.

If you ever find anything out let me know... will ya?

I was thinking about adding a couple gauges, such as fuel pressure, NOS pressure (whistling innocently) and I guess while I'm doing it I could put in a real oil pressure gauge, it just pisses me off that ford does this.

TIA
Brad


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Injection is nice, but I'd rather be blown. 99 Lightning, the best of both worlds!

 

The panel gauge needle deflection appears to be based on the result of analog-to-digital conversions of the voltages sent from the oil pressure switch to the computer, when the switch is closed and when it is open. The computer appears to make an 8-bit digital value (range = 0-255 decimal) out of the switch position with values above 176 decimal equating to low oil pressure, and values below equating to at least 6 psi oil pressure. See http://www.mustangworld.com/ourpics/news/99hec.htm

So it looks like the computer, seeing only two values for the switch (open and closed) will drive only the two deflections of the needle that we see (extreme left and mid-range). There is a faint chance that the computer -already has- the ability to interpret a full analog range of voltage and turn it into a linearly corresponding needle deflection, and we just don't know it. Based on this, an interesting experiment might be to measure the voltages, engine off and engine running, at the oil pressure switch sending wire, and then substitute a potentiometer circuit there to deliver all the voltages in between the two measured ones to see how the computer reacts. If the panel gauge moves as the potentiometer turns, voila; we're on to something and could then go forward with experiments with analog oil pressure sensors, etc. My guess is, FWIW, that things just aren't this easy.

-tvw


[This message has been edited by tvw (edited 05-10-2000).]

 

i believe the temp gage works this way. No matter what the temp is, it's right above the thing that looks like a thermometer. the other day, after driving home from work (60 miles), i parked and went into a 7-11 - back out in a minute or two. temp gage was STILL at the little thermometer. so i guess it's COLD, NORMAL and probably OVERHEAT.

 

Nope. the temperature gauge works like a real analog gauge. I have shut it down and been sitting in the vehicle during a snowstorm on a bridge in traffic ( do I sound as if I am happy summer is here? ), and it does indeed move down, and up when the engine is running and generating heat.

This engine needs a lot of cooling capacity because of the power, so you might be seeing a slow rise and fall during summer temperatures.

 

Although I have not researched Ford's system, the 97 GMC I once owned used a gage of similar type as the Ford. The reason given for the arrangement was that the computer "read" the oil pressure above 6psi and allowed the fuel pump relay to remain on to keep the engine running. I had a problem with having to excessively crank the truck to start, which was the fault of the oil pressure timer relay, which would delay the shut down feature of the fuel pump briefly to allow the engine to start. It is an additional safety feature to ensure that the fuel system does not remain active in the event of a crash or oil pump failure. Cost considerations probably did not allow both a real analog gage and a pressure switch for the fuel management system. Just a guess...do any Ford techs have a better view of their system? j.b.

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99 SC Sport, Silver color everywhere, 4.2 auto,3.55 rear gear, split bench, stock AM/FM @ 2 cheesy speakers w/Ford brand bedliner. Keep'n stock from the factory because we love it for what it is...One fine ride!