QuestionHi,
The engine light came on in my 1995 Chrysler Concord. Around the same time the car started very rough idle/skip when at stop. Code read misfire in cylinder #5. Fuel rail recall has been done. Intake manifold was replaced. Engine light still on and still skips at idle. Any ideas? Fuel injector? Thanks.
paul Carpenter
AnswerHi Paul.
P.S. Here is another response I gave a fellow who had a similar one cyl miss plus a general miss condition, just for completerness, but it is more extensive because it involve general missing not just one cylinder which should make you focus on those things related to cyl 5 only:
"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.
The code pointing to cyl #3 means the general problem is affecting that cylinder more than the others, but the approach to it is identical to that for the general misfiring problem, perhaps with a focus on #3. But the 0300 code is probably the controlling factor (involving multiple cylinder misfires rather than just one).
I can't give you any personal experience with this situation, unfortunately.
I'd be interested in learning what you find to have been the solution.
Roland "
Hi Paul,
It could be the injector but that would be only after checking some other things with greater probabilty:
check the spark ignition cable routing to cyl #5 and its connction to the spark coil unit and the spark plug cap. Then if possible to check in the dark, with the engine idling spray the cable lightly with water and watch for arcing indicating a need to replace the spark plug wire.
Remove #5 plug and check its condition. Insert screwdriver with insulated handle in spark plug cap so tip of driver touches center wire, then position shaft of screwdriver 1/4" from cylinder head and have helper crank engine for 5 seconds. See if spark looks strong. Then do it again for 5 seconds of cranking only this time back the shaft of the screwdriver slowly away from the head and watch for arcing at the spark pack end of that wire (indicating breakdown of insulation at the tower).
Check the spark plug to see if it is torqued tight (about 20 foot pounds).
Remove all the plugs and do a compression test with the engine warmed up (spec 100 psi +/- 25psi)
If all that checks out, then the injector is a possible reason to consider. But I would try to get a diagnostic readout/test done on the injector before getting into that possibility because of the cost and fragility of the fuel rail.
Let me know what you find or have other questions.
Roland
