QuestionRoland,
Changed Distributor cap and rotor. Still idles funny, sounds like a misfire and changes when car put in gear(No longer sounds like has a misfire. And when coming to stop light idles down low(maybe 200-500rpm) before coming back up to about 750 rpms.It is generating no codes at this time, in the past, the check engine would come and go. Checked 2,4,6 plugs and they looked the same and appeared to be in good shape. I guess the next step would be to change plug wires, but that involves removing the intake manifold. Would you recommend that as the next step and send the procedure to me. Thanks Hubert.
Followup To
Question -
Roland,
Have 97 Sebring with 2.5 V-6 ...Generating codes P0300-PO310. And Misfire on cyclinders 4&6. Can you provide any help? P.S Just had starting problem, which I'm told was a loose timing belt that had jumped time. Thanks
Answer -
P.S.
You might want to inspect the distributor cap to see if it is cracked, and with a little effort remove it (I can tell you the procedure) and inspect the rotor and measure the internal cap resistance (5,000 ohms). You could also pull spark plugs 2,4,and 6 which are the easy ones and see if they differ from oneanother, and check their general condition.
Roland
Hi Hubert,
I have the troubleshooting manual for the 2.5L V-6 and can summarize it this way:
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(catalytic converter), 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 fuel 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: valve timing, camshaft lobes, crankshaft sensor pick-up for debris in slots, drive sprokets properly positioned (this would be good to verify in light of your history), power brake booster (no vacuum leaks).
So I guess that beginning with the ignition wires makes sense unless you have an ignition 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 (primary is 0.6-0.8 ohms, secondary is 12,500 to 18,000 ohms). If it passes that, then focus on the fuel filter and pump.
The code pointing to cyls. #4 and #6 means the general problem is affecting those cylinders more than the others, but the approach to it is identical to that for the general misfiring problem. But the 0300 code is probably the controlling factor (involving multiple cylinder misfires rather than just one or two).
I can't give you any personal experience with this situation, unfortunately.
The plugs are supposed to be good for 100,000 miles if the ones that are recommended are installed. I can tell you about how to change the rear bank if you believe the plugs might be nearing the end of their life.
I'd be interested in learning what you find to have been the problem.
Roland
AnswerHi Hubert,
It is an improvement that the check engine light isn't coming on. I wonder if it might be worthwhile checking the action of the egr valve stem to see if it might be sticky in its motion in and out? The egr valve connects the front bank of cylinders' exhaust manifold to the intake manifold via a pipe. That valve is located near(under?) the transmission control module and you might get a better look at it by removing the three screws (middle of the bottom, front and back edges) and swinging it up and out of the way. The valve has a solenoid and transducer connected by vacuum hoses to the valve and which are attached to the cylinder head nearby. The valve proper has a round capsule fitting on the top and a saddle shaped frame holding that to the valve body. Inside the frame you will see a rod with a slot in it. If you start the engine, let it idle and then rev it to 2500 rpm and let it drop back you will see the rod move back and forth in response by observing the slot. It may be that it is responding slowly due to crud surrounding the stem inside the valve body. You can improve that by spraying some WD-40 on the stem and then also levering the valve in and out with the tip of a screw- driver to try and free up the spring-loaded movement. If you want to go further you could remove the vacuum lines and unbolt the valve from its connecting pipes in order to inspect the interior passage ways of the valve for crud which can be cleaned out with solvent to allow the valve to close fully in case the crud is preventing that, but this process is of course more of an effort. Maybe just try the WD-40 and see if that has any effect on the quality of the idle. The valve has to close tightly when the engine is dropping to idle rpm or it will cause a crummy idle.
To deal with the spark plug wires, and also the rear spark plugs here is what you have to do:
Here are the steps for removing and replacing the plugs on cyl 1,3,and 5 of the 2.5L V-6:
Disconnect negative cable from auxiliary jumper terminal (I believe this is the ground wire tied to the strut tower on the driver's (left) side of the car).
Unplug the connectors from the MAP sensor and (just to its front) the intake air temp sensor.
Remove the plenum support bracket bolt located rearward of the MAP sensor
Remove the bolt holding the air inlet resonator (the thing with words "multi-point injection") to the intake plenum.
Loosen throttle body air inlet hose clamp
Release snaps holding air cleaner housing cover housing
Remove air cleaner cover and inlet hoses from the engine
Unplug throttle position sensor and idle air control motor connectors.
Pry retainer tab back on throttle cable and slide cable out of bracket. Remove cable from throttle lever.
Slide Speed control cable out of bracker, if equipped. Remove cable from throttle lever.
Remove EGR tube from intake plenum.
Remove plenum support bracket bolt located rearward of EGR tube
Remove bolts holding upper intake plenum and remove plenum
Always remove the ignition cable by grasping at the spark plug boot turning the boot 1/2 turn and pulling straight back in a steady motion
Prior to removing the spark plug spray compressed air around the spark plug hole and the area around the spark plug
Remove the spark plug using a quality spark plug socket with a rubber foam insert
Inspect spark plug condition.
To avoid cross-threading start the plug into the cylinder head by hand
Tighten the spark plugs to 20 ft-lbs (28 N-m)
I would encourage you to make sure the egr vakve is good before doing all that, just to change the spark plug wires.
Roland
