I have a 97 XJ that has an intermittent miss. I recently changed the plugs, wires & coil thinking it was in need of a tune up. Last week it missed & stumbled pretty hard & threw a P0205 code.

I cleared the code and it came back the following day. The miss is definitely getting progressively worse. Yesterday, I replaced the #5 injector with a rebuilt injector from Bostech.

FWIW, I have 703 Neon injectors. I also have a 99-up intake installed. Both the injectors & intake have been on the XJ for over 3 years and the miss has just started in the last few months.

I've read that XJ's with the later intake had some type of heat shield to protect the #5 injector from heat soak. The miss doesn't seem to occur until the engine is up to temp, but it seems odd that if it was heat soak then why hasn't it been a problem for the last 3 years?

The connector and wiring both look ok, but I haven't unwrapped the harness to look inside.

Also, the miss is almost always under the following situations:
*Engine up to temp
*Almost always in overdrive (it's an automatic)
*Engine under relative light load (very light acceleration that doesn't cause downshift or maintaining speed going up a slight hill that doesn't necessitate a downshift)

It is so consistent when it misses that I know exactly when and where it will miss on my drive home from work before it even happens...strange

I've read that a TPS can possibly cause a P0205 code, but I'm unsure of how a TPS could cause the computer to see an open circuit to the #5 injector.

Any ideas?

 

It's unlikely to be heat soak. The problem comes from the California emissions package that has two cats directly below the intake. The common heat soak problem is also on hot starts not when just driving.

 

The more I research this and study the FSM the more I think it has to either be a damaged wire or loose connection in the power wire to the injector or a damaged wire between the injector & the PCM which operates the injector by opening and closing the ground.

I think I'll look in the harness for damage to the power wire to the injector. All of the injectors get 12v from a single splice. It is close to the fuel rail so it should be easy enough to inspect. If that looks good I'll run a new wire from the injector to the PCM. I'd rather run a new wire than cut open 5-6 feet of factory harness.

If it's not in the power lead or the wire to the PCM, then it pretty much has to be the PCM...here's to hoping I find a broken or damaged wire.

 

Think I just found the culprit. One power feed wire has insulation that was worn through where the wires exit the the long skinny housing that runs alongside the fuel rail.

 

That seems to have fixed it...we'll see.

I suppose that engine load, etc probably didn't have anything to do with whether it missed or not, but it probably did affect my noticing the miss...especially if it was a bit intermittent. A dead miss at low rpm under load is much more noticeable than at higher rpms or no load.

I'm curious what material that the harness trough if made out of. It looks like plastic, but obviously the wire was arcing to it. I wonder if it has graphite or some other carbon in the mixture making it somewhat conductive.

 

here's hoping you found the issue. I had the same problem and after all the same troubleshooting and replacing the injector wire harness complete, the answer was replace the PCM. That fixed it.