a general question about sensors

[Mac626]

I have a 94 Ranger 4cyl (8 plug) with a manual 5 spd.

I am having a problem with intermittant rough running. I plan to buy a tester to see what the CEL is trying to tell me, but I have a general question before I begin replacing parts. Here is how the problem manifests:

I am driving down the road and for no apparent reason, the CEL comes on. After a second or two, the engine runs rough and misses. This may continue for minutes, hours or even days. All of a sudden (again, for no apparent reason) the truck will start running properly again and the CEL light will go out.

Does this indicate a sensor problem or a mechanical one? I think it's a bad sensor, simply because it seems like a sensor giving a bad reading would cause this type of behavior. However, I wanted to ask the gurus here.

Thanks

[Psychopete]

The CEL means that the computer sees a fault in the electrical system. More than likely a problem with a sensor, especially since it's intermittent. I am thinking you can avoid getting the scanner on some 95 and younger Fords. If you can find the self-diagnostic plug, you should be able to follow this simple procedure to display the codes on the CEL.

http://www.troublecodes.net/Ford/

Pete

[Mac626]

Originally Posted by Psychopete

The CEL means that the computer sees a fault in the electrical system. More than likely a problem with a sensor, especially since it's intermittent. I am thinking you can avoid getting the scanner on some 95 and younger Fords. If you can find the self-diagnostic plug, you should be able to follow this simple procedure to display the codes on the CEL.

http://www.troublecodes.net/Ford/

Pete

Thanks Pete, I'll give that a try before spending the cash on the reader.

[Mac626]

Just a couple of quick questions, Pete.

I have a test light, but it looks like the MIL jumper set-up might be easier. As I read this, I set up the jumper wire, then turn on the key and record both sets of flashes to get the two digit DTC.

Looks pretty straightforward, but what is that part about continuous memory DTCs? Will it give me that after the regular DTC or instead of them? And are the CMDTCs on the three digit code chart, or the two?

Thanks

Mac

On edit: can this test be performed using all three modes?
(R) = Engine Running test (M) = Memory code (O)=Key On Engine Off test

[stuzman]

Originally Posted by Mac626

Just a couple of quick questions, Pete.

I have a test light, but it looks like the MIL jumper set-up might be easier. As I read this, I set up the jumper wire, then turn on the key and record both sets of flashes to get the two digit DTC.

Looks pretty straightforward, but what is that part about continuous memory DTCs? Will it give me that after the regular DTC or instead of them? And are the CMDTCs on the three digit code chart, or the two?

Thanks

Mac

On edit: can this test be performed using all three modes?
(R) = Engine Running test (M) = Memory code (O)=Key On Engine Off test

Although the link above for reading codes is given, I feel that this article gives a more detailed description of how to retrieve both sets of codes (KOEO and KOER) with three different ways of accessing the codes. Although the article describes a Mustang for its example, the system described is for EEC-IV which fits your Ranger. Hope this helps you out!

http://www.corral.net/tech/maintenance/eecivtest.html

[Mac626]

Thanks, Stuzman - that clears things up a lot.

I know what I'm doing when I get home