QuestionHi Roland, I was on vacation since our last entry.
I have included our previous posts, since I do not know how to "follow up" again.
I have since borrowed an OBD-II tester and the code indicated cam/crank sensor. The odd thing here is that I hit "clear" on the OBD-II, and I no longer get any error codes- but the car still runs very, very rough (will not idle, sputters, backfires, chugs, etc.)!
As far as the EGR, I have a handheld vacuum tool and can actuate the valve. I see a smooth movement of the shaft you have mentioned in many other posts, as well as it returning to its normal (spring biased) position.
In reading your other posts, do you think it is advisable to remove the valve and clean whatever I can?
I have not yet looked at the voltage transitions on the cam/crank sensors since I no longer get the codes. Do you think this is still a worthwile task?
As below, I am always looking for any source of a vacuum leak. Since I had to remove the upper intake manifold, I have been very sensative to those vacuum connections. Do you know of any sources of vaccum leaks on the backside of the lower manifold? I can see the PCV valve on the front of the lower intake manifold, but this looks ok.
Thanks for any help!!
Date: 7/10/2007
Subject: 96 Sebring hard start, dies quickly
Question
QUESTION: The car "died" at the grocery store- the starter would turn over the engine, but no spark.
the computer codes were 12 11 55
I had it towed to the repair shop where they replaced the crankshaft sensor. It now started hard, but ran extremely rough (missing, backfiring) would not idle.
The repair shop wanted to keep replacing items, but they admitted they had no real idea what was wrong, so I had the car towed to my house.
after resetting, the computer codes were still 12 11 55
I have since replaced the:
Idle air motor/valve
Distributor
spark plugs, ignition wires, cap & rotor
I have looked for any kind of vacuum leak- none i can find
I watched the alternator output with various loads and no apparent voltage spikes 13.9VDC
At #1 TDC both camshafts line up perfectly with their marks. The timing belt is in very good condition.
after resetting, The computer codes are still 12 11 55
I understand code 11 to mean bad crank sensor or bad cam sensor or timing belt
I checked the fuel pressure last night:
at key "on" it came up to 38lbs and while it was running (missing, backfiring, etc) it went up to 54lbs and always stayed in this range.
after some reading, i was going to suspect the upstream O2 sensor next- can i test this?
can I recheck the crank sensor with a volt/ohmmeter? how?
Thanks for any help/ideas.
Steve.
ANSWER: Hi Steve,
You have done a good job seeking the problem and reporting the results. I would suggest that you take a look at your egr valve to see if it might be clogged or the stem is sticking in an ajar position. Spray the stem where it enters the valve body with WD-40 or similar solvent.
I assume that you have disconnected the battery for a few minutes to erase the codes, so that you still are generating a "fresh" code 11. You are correct about the multiple possibilities for an 11 code according to my '96 manual for the 2.5 V-6. You might get a specific indication by using an OBD-II reader to separate the timing belt (1390), from the no crank sensor (1391) or cam/crank sensor intermittant, or too much variation in crank target windows (1398). You can observe the output signals from the sensors by probing the wires with fine pins, turning the engine via the bolt on the crank pulley, and with the ignition in the run position. Measure between the gray/black and black/light blue (crank) and the tan/yellow and black/light blue (cam) sensor wires. The voltage should oscillate several times between 5V and 0.3V for every full revolution of the crank. You might try shaking the harnesses to be sure that there is a good connection between each sensor and the PCM. The signal wires are on pins 32 and 33 respectively of the black plug, while the ground wire is on pin 43 of the gray plug at the PCM if you want to check for continuity.
The O2 sensor should read around 1V, but I suspect that is not the problem because it would set a code, and also because it doesn't come into play until a few minutes after starting the engine.
Please let me know what you find out.
Roland
---------- FOLLOW-UP ----------
QUESTION: Thanks, I will get on this tonight. I was unsure of whether the 96 model would take the OBD-II reader. I have seen them with "16-pin interface", do you know it this is what fits the mitsubishi 2.5L v6?
Roland, you are a great help, thanks again.
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Answer
Hi Steve,
'96 was the year when most models came with the OBD-II system and the associated 16-pin plug. Take a look for it under the dash at the lower edge near the steering column.
But try the other tests before investing in a code reader because you still have the ability to use the key to get the OBD-I system codes.
Roland
ANSWER: Hi Steve,
If the engine falters when you open the egr valve then it probably is open enough to not require removal for clean out of the passageway.
On the fault code absence, it still could be a weak sensor that is not so bad as to set a code, or one that is not at the proper spacing to the surface it 'looks' at. Even the crank sensor that was installed earlier could be bad or not properly positioned. So get a new spacer paper from the parts dept. of a dealer and reinstall that with the paper in contact with the surface. Then check the voltage pulsing from it and from the cam sensor in the distributor using a voltmeter and turning the crank by hand with a socket and handle.
I don't know of any specific vacuum leak points on the manifold.
That is what I would do next. Thanks for the update and do let me know what happens.
Roland
---------- FOLLOW-UP ----------
QUESTION: Roland, I think you are correct.
Since my last entry, I reset the PCM by way of disconnecting power (instead of "clear" with the OBD-II), I now have the bad cam/crank code back.
Your calling out the pin#/color codes of the cam/crank signals were extremely helpful. I watch the cam sensor go high for one revolution of the crank and then low for 1 revolution of the crank. Note: at the low/high or high/low transition the fuel pump activates.
Watching the crank sensor is far, far more complicated. I am seeing rapid transitions (for example, high/low/high with 3 degree turn of the crank), and long periods (approx 20 degrees rotation)of high or low signal with 5 degree periods of the opposite. Is this output documented anywhere?
Since I did not replace the crank sensor to begin with, could you elaborate on the "spacer paper"? Is this a separatly sold item from the crank sensor?
I think we are narrowing in on this problem for sure.
Thanks for all your help.
AnswerHi Steve,
The cam of course turns half as rapidly as the crank, and what you are seeing there is correct because there is a shutter that is open or closed for 180 degrees of rotation of the cam (or 360 of the crank). On the cranks sensor: the flex plate has 12 slots grouped in 4's, so three groups, and they are separated by 20 degrees between slots within each group, and then a space of 60 degrees before the next group of 4 slots, etc. So you ought to see the high/low/high as one slot, then 20 degree and another high/low/high, etc. with a 60 degree space after each set of 4 high/low/highs.
That sounds close to what you see, no? The paper spacer is supposed to be either temporarily stuck on the tip of the sensor or if separate you are to stick on the tip before you install the sensor. Then install the sensor so it is pressing against the metal in a "non-slot" area of the flex plate. Then as the crank rotates that paper will gradually wear away but leave the tip of the sensor close to but not touching the metal. So with that in mind, see what you think, and if the pulsing and spacing is to your liking and you still get a code I would try to verify that the wires are patent between the sensors and the pcm, and even shake the harness to possibly divulge a broken wire.
I am glad to learn of what you observed and look forward to further reports.
Roland
