QuestionQUESTION: I have codes 54 and 11. We have replaced the crank sensor and cam sensor. Timing belt is fine. We have spark and fuel. Battery isn't but a year old. We can't get the 11 or 54 codes to go off. Code 11 says "Battery input to PCM disconnected within the last 50 starts." I have had trouble with the defrost coming on whenever it felt like it and not going off. How can we ensure that the PCM is bad before I fork out $475 to get a new one? Or could it be something as simple as a wire from the battery to the PCM?? Any help would be appreciated.
ANSWER: Hi Sherri,
There is a bit of confustion here. The code 11 says the crank sensor signal is absent. The code 54 says the cam sensor signal is absent. Now those could be stale codes, present before you changed the sensors. You can erase old codes by simply disconnecting the battery for a minute or so. But when you do that it sets a 12 code (which is what you called 11) and that will only go away after 50 on-off cycles of the key code. So I would begin by erasing the codes, to get rid of the 11 and 54, and of course set a new 12. Then try to start it severeal times and see what the fresh codes are other than 12. Let me know and we'll go from there. There are codes for faulty pcm's, such as 52, 53, 63. Absent those, I would not replace the pcm.
If you have spark and fuel, then maybe it is a mixture issue, such as the exhaust gas recirculation valve being stuck ajar.
I would take a look at the exhaust gas recirculation valve which is located behind the engine near the air intake throttle valve. It is mounted in a pipe that runs between passenger side exhaust manifold and the air intake manifold. The valve is mounted horizontally and has a valve stem between its round vacuum actuator top and the body of the valve attached to the pipe, inside the flange that connects the two parts. The stem has a slot into which you can insert the tip of a flat-bladed screwdriver so as to lever the stem back and forth against spring action which should move freely and close tightly. If the stem seems to be sticky so that stem doesn't close all the way by spring action, then you can try spraying some penetrating solvent like WD-40 on the valve stem to freeup its motion.
If the valve is sticking slightly ajar it will make for to start because the mixture is too dilute. It is one of the most common causes of this symptom. So see if you can find the valve and check/lubricate the stem. To check it in motion you can rev the engine from idle to 2500 rpm and back to idle and watch to see if the valve stem moves freely in both directions to the extreme open and closed positions. It may be that the interior of the valve is cruddy so that might require that it be unbolted from the pipe where it it attached and cleaned. But chances are good it will only be a sticky stem. Feel free to write back with the results and other questions you might have.
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QUESTION: Hi Roland-
I guess I should've said that the car would crank at first but not turn over. We sprayed starting fluid and it would run for a few seconds. Then after a few million tries it began backfiring through the airbox and won't start at all now, even with starting fluid. That's when we did the codes and replaced the sensors. Fuel pressure is at 45-50psi, so we know the pump is good. Timing belt is lined up with the dots. The guys are telling me they didn't think it would be the EGR valve and that I should tell you what I just did. Do you still think it could be the EGR valve?
AnswerHi Sherri,
I think if the egr is slightly ajar when you try to start it that the mixture will be too lean. That is why I suggested checking that. The mixture can also be affected by the engine coolant sensor and the MAP sensor being off-value, but there are codes for those two item, but no code for the egr. So be sure to check the egr as I described it, to make sure the stem is seated in the full-closed position by means of the internal spring action. And of course, re-check for codes.
I have had a situation where my MAP was working but not accurately, but not so bad as to set a code. So see what the MAP voltage signal is while cranking it over is another possible test.
Roland
