QuestionHi Roland,
1997 Chrysler T&C minivan 3.8
Backfiring, missing under load. Engine code: 43 multiple misfires. Changed plugs and wires.
Reset A/C (flashing lights)
Ran fine for 2 days. Going down road at 50 mph, engine quit, not stalled, just quit, I didn't even realize
it had quit running. Would not restart,
Trouble code: 54 no signal from cam sensor. I didn't check the code until after I had tried to restart it.
Changed cam sensor and crank sensor. Still no start, engine coughs like it wants to start. Had it towed home.
Pulled ASD relay, 12 volts at pin 30. Got engine code: no output voltage from ASD. (this was from when I had the ASD relay out while checking voltage)
Changed ASD relay. (this gave me a spare relay to work with) Pulled dash and resoldered connections on main instrument cluster connector. ( 2 cold solder joints found)
Jumpered fuel pump relay, fuel pump working. Getting 12 volts at fuel injectors. Pulled front spark plugs, getting a weak, orange, erratic spark. Plugs were wet with gas.
Getting 8.8 volts at cam sensor input. Getting 12.65 volts at battery. Getting 10.6 to 11.4 volts at coil pack while cranking. Getting 11.6 volts at battery while cranking.
Checked resistance on coil pack, got 0.80 ohms on the primaries and 12k on the secondaries. The spec for the primaries is 0.45 to 0.65 @ 70 to 80 degrees.
It was 90 degrees. Secondaries spec is 7k to 15.8k.
jumpered the ASD by wrapping a piece of wire around terminal 30 & 87. Those are the pins that short together when the relay is activated. Plugged it back in and tried starting.
No start. But it did set a 42 code: shorted or open ASD....
Did cold boot on PCM. Still no start and no codes.
The only test tool I have is a digital multimeter and a continuity tester.
AnswerHi Rick,
Thanks for the very detailed and technical history. I would suggest beginning with a check out of the egr valve to make sure that it is closed tightly as an ajar valve will cause a too lean mixture to sustain an idle. It is located underneath the throttle body and is mounted in a pipe that comes to the area from the right exhaust manifold. The valve stem is in a flanged area between the round top and the valve body proper, hidden by a flange. You'll find a slot in the stem into which the tip of a screwdriver can be inserted that allows you to move the stem back and forth, against spring-action in one direction that is trying to close it. Make sure that spring causes the stem to come to a full close stop. If it is sticky in action spray some WD-40 on the stem and work it some more.
Then try to start it.
The multiple misfire code is a catch all. Here is how I answered recently to a fellow who had that code as well as specific cylinder misfire:
"The codes are based upon the detection of minor missing which causes subtle differences in the rpm as each cylinder fires to produce its rotational input (crankshaft speed sensor is the detector involved). The Chrysler troubleshooting manual lists the possible causes as:
secondary ignition wires, puel pump or fuel filter, injector harness connectors, ignition coil circuit, spark plugs, mechanical engine problem, contaminated fuel, water in fuel, PCM grounds, Injectors, Restricted exhaust, intake restriction, PCM, evap system, EGR system, Air gap at high rpm's, damaged sensor trigger wheel. That is quite a list!
The approach suggested is to check all electrical connectors and wiring, then do the tests in the following order:
secondary ignition
fuel delivery
engine vacuum
PCM power and ground connections
engine mechanical
The first one uses an engine analyzer scope to look at the high voltage pattern, then spray water on the cables to see if it changes. The possible repairs: individual spark plugs, coil or cable replacement
The second one involves pressure measurement and from there a variety of possible solutions
The third involves reading the intake manifold vacuum to see if it is steady at between 13 and 22 inches of HG. and if not the suspects depend upon the pattern shown by the gauge.
The PCM involves checking various wires at the PCM plugs
The last involves engine compression testing and a variety of other mechanical checks.
So I guess that beginning with the ignition wires makes sense unless you have a scope and the experience/knowledge at interpreting the patterns. You might try looking at the wires in the dark with the engine idling, then also spray some water mist on them to see in either case if you see arcing which would be a sign that the wires' insulation is breaking down. Then measure the coil resistances. If it passes that, then focus on the fuel filter and pump."
I know you have checked some of this already, but if the egr doesn't solve it, then consider some of the above and let me know what the status of codes is at that moment.
Roland
