Chrysler Repair/'97 3.5L Won't Start
QUESTION: Hi Roland. The camshaft sensor checked OK. I got the 5.0v and 0.3v signals when I slowly turned the engine by hand. The crankshaft sensor was showing 5.0v and 0.025v, so on the outside chance that the PCM was expecting 0.3v on the low side, I replaced the sensor. No change.
I moved the rod on the EGR valve with a screwdriver and it seems to move easily and stop positively. I could still try removing it if you think there's something to that.
I checked the resistance one the coil primary side again, 0.6 ohms each.
One difference I noted now is that there is no ground signal from the PCM to the coil on the red AND the white wires, meaning two sets of cylinders not firing. And I noted that the starter sounds different when it's cranking now. I actually had to look at the belts to confirm the engine was actually turning, which leads me to wonder if the different sound is due to no compression. Could the timing belt have jumped enough to do this?
Which leads me ask, is there a way to check the timing without exposing the timing belt? Any trick? I haven't seen anything that might tell how to do it by looking at the sequence of the camshaft sensor pulses and the crankshaft sensor pulses, but suspect that's possible.
ANSWER: Hi Mike,
If you are getting all the pulse sequencing from the sensors as I described then in theory the pcm should be able to do the coil primary wire groundings reliably. Are you sure there is no code for a faulty pcm? Try the on-off-on-off-on with the ignition key and see whether you get check engine light flashing showing a 53 or a 54, and then a 55. The '97 model could produce both OBD-I codes and OBD-II codes as that was a transition year. The timing belt being slightly out of adjustment shouldn't stop the grounding out, it would seem. Maybe the easiest approach would be to see what the cylinder compression readings are. Should be even and around 100 psi.
Clearly, the issue is there is no driving (grounding) pulses for four of the six cylinders, but the sensors are pulsing, so it either has to be the belt has slipped significantly and the cam signals are displaced from the crank signals so much that the pcm doesn't recognize the pulse timing sequences OR the belt/timing is ok and the pcm is bad. If it is cranking more easily then that might well indicate that the belt has slipped such that the compression is down.
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QUESTION: Thanks again Roland. The only codes I've seen this whole time are 12 (battery) and 55. When I was testing the camshaft sensor and removing the wires, it triggered "11" (no crankshaft pulses to PCM). But that went away once I reconnected the camshaft sensor.
I'll try the compression tonight.
ANSWER: OK, let us see how the compression looks.
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QUESTION: Hi Roland. I did the compression test tonight. I've never done one, but I got a result I didn't expect and which doesn't make sense to me.
The right side (1, 3, 5) went to 135, 140, and 110 after 4-5 cycles. The left side only got to 35, 60, and 50 after about 3 cycles. I expected low compression all around, since everything is connected by the belt. I looked for an explanation on-line with no luck. I suspect you'll have an idea though.
Recall that only yesterday did the sound of the starter during cranking change noticeably. During all the attempted starting I did last week it sounded normal. So it doesn't seem like a condition that arose while the engine was running. The oil looks normal.
On the Intrpeid forum there's all sorts of contradictory postings about 1st Gen 3.5 engines hitting when the timing belt is out of whack and bending valves. But the official information says they're free-wheeling, which is as you said.
I wonder whether the timing belt has slipped (at the left sprocket) such that the left bank valves are out of synch with the crank but the right side are not. That left side is also the side which the cam sensor is detecting so that would put the timing out for the spark id'ing as well. This is a guess on my part but it does suggest that you do have to remove the covers to check out the timing belt situation. It could also be an issue with the left side sprocket to valve shaft as an alternative. But in any case those left valves are wrongly positioned. I recall you said at the start of this that the belt had been changed recently.
Let me know what you find. Best of luck.