The CEL in my 94X has been lit for quite some time now, but since it's getting close to smog time, I'm going to need to fix it.

KOEO-
111
Then-
172
212
214

KOER-
17
25
36

From what I can tell from those #'s, it's running lean on one side, there's an ignition issue, the spout connector is shorted out (where is it on my X), and it's spitting out non-existant codes(?).

Background- plugs were changed a month ago, pass side O2 a week ago, driver's O2 a year ago, plug wires, and fuel filter new a year ago (at the time I had a tech hook a guage up and the pressure was good). There is a definate flat spot at initial throttle tip-in/light throttle, much like a carburated car would feel like until it's warmed up.

Of course, I'd rather avoid throwing $ at various incorrect parts, suggestions appreciated. :thumbsup:

SOP when working on DTC's is to resolve KOEO codes first (you're already passing KOEO), then move on to KOER codes. So I would probably first suggest working on why you aren't getting correct KOER codes. Could they possibly be 172, 536?

With those CM 212/214 codes, I would probably also suggest you clear CM and test drive to see if those codes come right back.

I did clear them, they came right back.

I guess they could be 172 & 536? I'll check.

I think I am going to change out the fuel filter, I remember a local tech told me that the gas station tanks around here are really dirty, and that's not unusual to have to change out filters on a yearly basis.

Thanks for the reply, I'll keep you updated.

I'm pulling this thread back out with an update and a question.

After changing several parts and still coming up with the same basic issues and due to a lack of time I decided to pay the local tech to figure out why my CEL was still on.

One of the O2 sensors shows a dead short. He has decided that the actual computer has had a mild stroke (thankfully it's not the harness, which was the other possibility), and needs to be replaced.

So- my question is- will any 1st gen A/T computer work, or do I need to find another Limited model with similar VIN's? I presume a 2nd gen ECU won't work, even if it was from a 4.0 OHV motor?

Thanks!
:us:

Direct replacements for your '94 PCM will come from a '93 with sequential injection or a '94. Some '93, '92, and '91 used a batch fire model for firing the injectors and, therefore, aren't direct replacements. A '95+ PCM would be looking for the all electronic 4R55E or 5R55E transmission and won't know what to do with your A4LD.

That's not to say that they couldn't be made to work, but it would require other modifications (wiring harness, transmission, and/or sensors) to work properly. Since you seem to be after a direct replacement with a minimum of effort, stick with a '94 PCM or a '93 (with SEFI).

Mr Shorty, you're quite the scholar on EEC IV items. Well done.

How can I tell if a 93 is SEFI or batch-fire?

Matt Fisher

How can I tell if a 93 is SEFI or batch-fire? Your '94 has SEFI, an EGR valve, and 2 O2 sensors. My '92 is batch fire, no EGR valve, and 1 O2 sensor. '93 transitions between the two styles. Some are like my '92 (no EGR and 1 O2 sensor), and some are like your '94 (EGR, 2 O2 sensors). I've heard it said the difference is between Fed emissions (like my '92) and CA emissions (like your '94), but I can't be sure that it's that clear cut. As I understand it, if you find a '93 that's like your '94 (EGR, 2 O2 sensors), then the PCM should work in your '94.

Update:

I picked up a computer from a 93 SEFI Explorer, that seems to have done the trick- no more CE light. As a bonus, the ABS light is much less likely to come on.

While I was at the wrecking yard, I picked up a MAF from a 97 Lincoln Town car. Made of plastic, it appeared to have much greater flow capacity than the stock metal unit. Although it took a bit of lube to get the stock air intake pipe on, the other end bolted right to the airbox, and the stock electronics fit right in there. I also cut a 1"x6" hole in the bottom side of the airbox. Although I'm still running a paper filter, there was a substantial increase in power.

The fuel economy still sucks, and it's still gutless, but not quite as gutless now, and no CE light is a good thing.