QuestionRoland reading your posts has saved me LOTS of $$$ and I thank you tremendously !! I just used the ignition switch to read codes--12,43,21,52,43. I did recently change battery and had transmission work done. Car has started idling rough when in gear. I also changed timing belt and water pump a month ago. I am also losing coolant and can't pinpoint location, I have to add water every week or so. The engine never burns a drop of oil between changes,. Any help would be greatly appreciated !!! Thanks Jamie
AnswerHi Jamie,
You are very welcome.
I assume that you have either the 3.3 or 3.8L engine in the car, because the 2.7/3.2L engines came out in the '98 model year, I believe. The 21 and 53 codes both speak to problems with the oxygen sensors, but unfortunately the self-readout doesn't say whether it is the left or the right side sensor that is acting up. A readout using an OBD-II reader plugged into a socket under the dash next to the steering column would tell you which one is at fault (P followed by a four-digit number). You might get a free readout at an Autozone parts store, or find a "special" at a shop for around $40.
On the rough idle, the 43 code is saying there may be a problem with the spark coil. Check the resistance between the common 12V input pin of the 4-pin socket at the coil (which is the one on the upper right if you consider the side of the inner surface of the socket with the bulge to be the bottom of the socket) and each of the other 3 pins of the socket which you should find to be 0.45-0.65 ohms, and also check the resistance between each of the three pairs of spark output sockets which should be 7,000 to 15,800 ohms. If those measurements checks out then you may find that the code readout also gives you a better handle on the cause of the miss, which could be several possibilities. It could also be a problem with the "driver" wires from the PCM to those three socket pins, so let me know the engine and I can give you the pin assignments to check the continuity of the harness.
The loss of water with no sign external on the engine or cooling system as the source leads me to wonder if you might have a slight head gasket leak which is manifested by excess white smoke coming from the tail pipe immediately following a cold start. Such a leak could cause a miss as well. So watch the exhaust immediately after you start the engine, if the condensate on your hand held in the exhaust stream smells like antifreeze then that would corroborate such a leak. Then the question would be which bank of cylinders has the leaky gasket. That you could tell by alternately disconnecting plug wire to find if one of the six when disconnected doesn't make the idle more rough, which would mean that cylinder is not combusting well already due to a presumed gasket leak.
Of course the rought idle could also be due to a slightly stuck ajar egr valve so check the function of the stem of the valve by levering it in and out with the tip of a screwdriver in the slot of the stem to assure free movement to the full closed position via the internal spring.
Those are the sorts of approaches I would recommend. Let me know as you learn more and tell me the engine you have should you write back. I have the trouble shooting manuals for these engines to work with.
Roland
