I have a 93 Town car that runs good until it warms up to normal running temperature, then the check engine light comes on and the car falls all over itself and sometimes stalls. I have changed everything but the kitchen sink Re; fuel filter, fuel pump, gas tank, IAC motor, TPS, cleaned out cats and when you scan it no codes show. HELP!
How do you “clean out the cats”?? I think this model still uses the OBD-1 system and pulling the codes is considerably different than modern cars…How many miles on this car? Just on a hunch, I would disconnect the EGR valve and see how it responds to that…
Thanks for responding…the car has 230,000, car still has R12 freon, I had someone use a cutting tool to open up the cats, empty the contents and then weld them shut. I had 2 mechanics tell me that’s what my problem was but car still does the same thing, I will disconnect the egr, and hope that’s the problem, I forgot to mention that I also replaced the o2 sensors. Caddyman? I’ll bet you’re glad they stopped making Northstar engines?
You need to use either a code reader that is specific to this car or has this cars program loaded into it or you follow a procedure to cause the CEL to flash in a pattern that gives you the code(s). Then you need a manual specific to this car to cypher the code(s).
You might get the information you need by googling for a forum dedicated to this car or early 4.6 engines or even a site dedicated to early Crown Vics
With the cats gutted, you are doomed to having a CEL all the time… “Catalytic Converter efficiency below failure threshold”…Something like that…The rear O2 sensors will send the same signal as the front ones…
So now you don’t know whether the CEL is related to your problem or not…On those early 4.6 engines, the small EGR delivery pipe gets plugged up and you get a “EGR low flow” message. But that will have little if any effect on performance…
This year model should be one of those TFI ignition module equipped ones. These modules are prone to failure and symptoms can vary. Testing the module is an exercise in futility unless it just flat fails for good and car quits completely.
It’s the gray module on the side of the distributor. If you change this module you MUST use the special grease that comes with the new module or the new module will soon fail.
In retrospect, and while removing foot from mouth, this car is not a TFI model. For some reason I was thinking of the 5.0. The problem could still be related to the module though.
Another possibility is a failing ignition switch; the electrical part. This would not be unheard of considering the mileage and the possibility that the cabin fan blower circuit may be routed through the ign. switch instead of a relay. A dragging cabin fan over the years pulls much more current and it all flows through a plastic switch.
I haven’t pulled up a schematic to see whether this is true on the 93 TC or not but it does apply to a number of other Fords.
If you say that AS SOON AS it warms up the check engine light illuminates and THEN it falls all over itself…Then that suggests to me that it could be an EGR issue…The EGR gets the signal to actuate when you reach OP temp… VERY much worth looking into… Have you looked at the EGR…cleaned the port for it…made sure it was working?
Another possibility is a vacuum leak. There is a vacuum tee on the back of the plenum on those 4.6s that is quite well hidden and has a tendency to rot out and cause just this sort of problem. Trace your vacuum lines and replace anything that is rotted out or close to it. I also agree with others who have suggested an EGR problem. Add to that any solenoid that actuates the EGR valve and the DPFE sensor if this car is so equipped. If the EGR valve is open when it should be closed, particularly at idle, you will have stumbling and poor idle. The EGR valve itself is not likely the problem, but it’s easy to test. Feed vacuum to the valve with the engine running. It should stall or come close to it. Remove vacuum before the engine stalls. If it picks back up right away and smooths out, the EGR valve itself is okay. If you disconnect the vacuum source to the EGR valve, drive the car, and no longer have these issues, you will be looking at an issue with the EGR solenoid or possibly DPFE sensor.
checking your excellent suggestions…will respond asap
You and I are the only ones talking about an EGR Markus… Either we are nuts or are on to something…LOL