I have a 1995 Ford Contour. I've been trying to figure out what's wrong with for about a week now. I've replaced a ton of components, tested a ton of them as well, but nothing is working.
Anyways, I noticed that my PCM is not giving me any codes...even when I disconnect the MAF Sensor, or IAC, etc.
How can I not be getting a CHECK ENGINE light as SOON as I am disconnecting an important sensor!!!???? Is my PCM shot??
It does not light up the check engine light as soon as you unplug a sensor.. hell i had my o2 sensor unplugged on my 1994 dodge spriit for a whole day and it still didnt come up with a failure. People rely on the damn computers in the car to act too fast... it likely writes a code to its memory that the sensor failed... but it may take 20 or 30 small failures to cause a check engine light... I do not know how their code was written this is only what i assume.
OBD II systems often require several logged failures before the MIL is illuminated (depending on specific fault indicated). EEC-IV is not OBD II compliant, but I would suspect that it may follow the same pattern. Those older ECMs aren't necessarily the greatest anyway, as they lack monitor routines, ie, they don't have active sanity checks for the associated components. Furthermore, if one is (dis)connecting components before the ECM enters closed loop, it possibly won't log anything anyway, at least not to the point of illuminating the MIL. Disconnecting the MAF should make it pretty much run like shit however, and probably stall, regardless of loop mode. It should be requisite (along with CMP and CKP) for the PCM to follow its default fuel map.
What's the original problem? When you turn the key from OFF to RUN (not start) do you hear the fuel pump run for a few seconds? Does the "Check Engine" light come on right then?
If the ECA's not coming on, it's not going to check anything.
Not at all. If you don't see the "Check Engine" light come on when you turn the key from OFF to RUN, (it's not a code, it's simply telling you that it's "booting up" so to speak), and hear the fuel pump run for a couple of seconds, then it's likely the ECA/EEC-IV isn't turning on. If it's not on (and there's a sequence of events that occur to turn it on) then it can't go out and get check the state of the sensors. Like your PC, if it's not on, you can't tell if the keys on the keyboard are any good.
Get back to us after you've hooked everything back up. You give us symptoms, we'll come up with some things to check for.
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