Mechanics

CHRYSLER LHS SPARK PROBLEM

1997 Chrysler LHS • 117,000 miles

My father has a chrysler and it had a miss so we hooked it up to diagnostic computer and it said we had a misfire in cylinder 2 and 5 and to change the cam position sensor so we did and it was a little better so we decided to replace the plugs and plug wires bad choice I guess the car is now worse it has no power and now is backfiring what else could it be I would appreciate it if someone could help me with this matter
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Jill909
January 19, 2013.




The fault code did not say to replace the camshaft position sensor. Codes never say to replace parts. They only indicate the circuit or system that needs further diagnosis. About 50 percent of the time the sensor in question is in fact the cause of the problem, but it's just as likely there is a wiring problem or a mechanical problem related to the sensor. Rust or metal filings on the end can interfere with generating a signal. Corrosion between two mating connector pins can reduce the strength of the signal. The engine will not start if either the camshaft position sensor or crankshaft position sensor is defective but on some engines, if the cam sensor fails once the engine is already running, it can continue running until it is stopped, then it won't restart. The cam and crank sensors rarely cause a misfire on just one or two cylinders.

Since it runs worse with the new parts, double-check the spark plugs' gaps, and be sure the plug wires are routed correctly.

Caradiodoc
Jan 19, 2013.
Hi we are puzzled by all of this after we changed the wires and spark plugs and the car did start but backfired and ran real bad and now the car won't start at all. Please give me any advise you have thank you.

Tiny
Jill909
Jan 19, 2013.
First of all, since we're talking about an engine running problem, we need to know the engine size.

If you've rechecked your work, the next thing would be to view live data on the scanner to see what the Engine Computer is seeing. In particular, the MAP sensor should have recorded approximately the correct current barometric pressure.

A compression test may be in order too. If the timing belt has jumped enough teeth, there could be bent valves.

Caradiodoc
Jan 19, 2013.
Okay the engine is a 3.5 and we recheck the wire and the cars will start but it is still missing we checked for spark of the coil and we had 2 wires not sparking number from 3 and 6 now does that mean the coil is bad

Tiny
Jill909
Jan 19, 2013.
It could be but you must realize that unlike the old single coils that worked with a distributor, this system has three individual circuits, and each one includes two spark plugs, two spark plug wires, the coil's secondary winding, and the cylinder heads to form one big loop. A break anywhere in that loop causes current to stop flowing and there will be no spark at either plug. That means one open plug wire will cause a loss of spark at both spark plugs.

To start with, measure the resistance between the two spark plug wire terminals on the coils. Compare the two that are working to the one that isn't. If there's a significant difference, suspect the coil pack. If they all measure about the same, the non-firing coil could still be arcing internally. To know for sure you would just have to try a new one.

Another trick is to disconnect both plug wires at the coil, then fashion a spark gap between the two coil terminals. You can bend up two pieces of wire to sit in each terminal with their ends almost touching each other, with about a 3/16" gap. If you don't get a nice solid spark while cranking the engine, replace the coil pack. The preference is to not use just one piece of wire to do that. With one end anchored in a terminal and the spark jumping at the other terminal, carbon is left behind by the arcing, and you don't want that carbon to be at the terminal. Carbon is a conductor and can short out the spark after the original problem is fixed.

If you have a scanner that has the automatic test mode feature, you can use that to cycle the individual ignition coils on and off so you don't have to crank the engine to do the testing.
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Caradiodoc
Jan 20, 2013.

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