VX CEL Issues
 

Update: 6/9/08 I replaced the distributor and that fixed the code 9. I still have the code 48 (lean fuel sensor) to contend with.


This seems to be the place for VX experts so hopefully someone here can help. Bear with me through my long description:

I have a 1992 Civic VX I picked up a few months ago. It had the check engine light on when I bought it. It was throwing codes 9 (cylinder sensor) and 48 (O2 sensor). I pulled up the diagnostic steps from Mitchell. They showed no problems with the sensors or wiring. The ECU was the only possible issue. So I started looking for another ECU.

Well, it turns out my car is a California emissions car. The difference between Cal. and Federal emissions cars is the Cal. one does not use a 5-wire o2 sensor. I guess lean burn produced too much NOX for California. The thing is, my car has a 5-wire sensor on it. So I did a little research and found out that all '92 VXs came with the 5-wire. The only differences between Cali. and Fed. was the ECU itself. After asking around, I was told a FED. ECU would work on my car and it would give me lean burn.

I found a fed. ecu. I hooked it up, and the car started and ran fine, but the check engine light came back on. It was showing the same two codes: 9 and 48. I ran through the diagnostic checks again, and came to the same conclusion- bad ecu!

So, what do I do now? Is it common for VX ecus to go bad. It seems like too much of a coincidence for both computers to have the same problem.

Has anyone else had this problem? Should I try picking up another ECU?

Does the check engine light stay on all the time? How's your mpg? You should be getting no less than 40 or something is seriously amiss.

Are you sure you have the codes correct? Since you have two codes the dash CEL light should flash 9 times short four times long and eight times short and repeat this sequence over and over.

If you do have a code 9 and 48, it makes no sense that the ECU would be faulty. What's more likely is that the distributor is faulty and that is making the engine misfire which in turn triggers the code 48. Don't completely trust the troubleshooting procedure given in the shop manual. It doesn't always find every fault.

You should buy/borrow another TD-42U distributor and find out if the code 9 disappears. If so the code 48 might go away too.

The gas mileage is low to mid 40s. The CEL is on all the time. I haven't noticed any misfiring. Thanks for the help. Besides Ebay and junkyards, what's a good source for a distributor? Is the VX distributor special or is it the same as other VTEC d-series (EX, Si, etc.)?

Yes, the VX distributor is special. The D15Z1 and D16Z6 share the same TD42U dizzy. You can try going to an Autozone or Advance Auto for one and return it if the code doesn't go away. I bought a rebuilt dizzy on Ebay for $60 shipped.

Do you know if a D16Y8 dizzy will work?

No idea. All I'm sure of is that the dizzy must be a TD-42U for a VX engine. Go to www.hondapartsdeals.com and research it.

What I've read in a few places is that Honda ECUs go bad rarely or never. So the odds that you really have two bad ECUs seem to be extremely small.

Your mpg is OK but not great. I bet it will go up, especially with the Federal ECU, once you solve the CEL problem.

Swapping the dist seems like a good idea. Here's something you can do first: check the timing. At Harbor Freight you can get a timing light for about $12.

No, a Y8 distributor will not work. ONLY an OBD1 SOHC VTEC D-Series distributor will work.

That's your problem for sure (unless you hacked your wiring). Honda distributors and their internals unfortunately are notorious for going bad. If you buy a used distributor, you have a 50% chance of it also being bad.

Thanks for the help.

How do I test my distributor to see if it's bad?