QuestionHi Roland,
I have '98 Cirrus v6 2.5L with 115k on the odometer. It developed ignition problem. When cold, it seems not to fire on all cylinders. The "engine" light is on. Code read is 302, 303, 305 "random cylinder misfire". I have replaced new spark plugs and cables and it did not help. It slowly gets worse every week.
It tends to behave better on higher RPM. Even when hot, it will show the problem on low RPM, but not so bad than when it is cold.
It seems to have full power on highway with higher RPM and accelerator pedal depressed.
I suspect the computer module that probably holds the ignition electronics. Probably not the coil, since it seems to fire on sometimes 2, 4 or 6 cylinders. From my limited experience, the coil when it fails, it fails for each cylinder pair. I think this car has no distributor. Let me know what you think. Thanks in advance. -Andy
AnswerHere is the procedure to remove the distributor cap:
remove the bolt holding the air intake resonator to the intake maifold
loosen clamps holding air cleaner cover to air cleaner housing
remove PCV make-up air hose from air inlet tube
loosen hose clamp at throttle body
remove air inlet tube, resonator and air cleaner cover
remove EGR tube
remove spark plug cable from distributor cap
loosen distributor cap hold down screws and remove cap
note position of rotor and remove rotor
Assembly is the reverse
Hi Andy,
No the 2.5L V-6 has an integral coil/distributor, a rotor and cap. So you might want to check the condition of the rotor and the cap. I can send you the steps for doing that from the '96 manual which is what I'm using as a reference.
The trouble shooting manual for the 2.0, 2.4, and 2.5L engines pretty much says this about multiple misfires:
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.
But there is no distinction in the discussion between the 2.0 and 2.4 vs the 2.5. The former don't have a distributor or rotor, so that is why I would suggest that you check those out. I will look thru my archive and find whether I have the 9-step procedure already 'processed' and forward it to you as a follow up in any case.
Roland
