Hi
My Chrysler G Voyager had som misfire issues earlier this year and I have replaced this:
PCV valve -coil and coil connector/harness-plugs and wiring-map sensor-fuel injectors and fuel rail wiring harness- gasket plenum intake and throttle body- O2 sensors- battery-manifolds.
The car was fine, drove about 3000 km and then lost Power day by day. Runs fine at idle but powerloss when driving, gets 20 km/h. Get the P0300 random misfire.My mechanic cant find the problem and he change the ECU and still the same. No noises sounds very good at idling.
Any ideas anyone?

 

Have you resolved this issue?

 

No, dont know what to do.

 

There are a number of possibilities with just a generic misfire code. Have seen many instances of crank and cam sensors going bad and NOT throwing a code. Also at year age, could be a weak fuel pump. Where is the vehicle located as you post in Km and not miles(USA)?

 

New fuel pump too, located in Norway, Europe.

 

Replaced the throttle body...did you replace the throttle position sensor on it? Still also suggest the crank and cam sensors be checked. Also possible plugging up cat converter, will run well at idle but under higher load, not flowing enough exhaust thru.

 

The cat is ok, I will check sensors. Thank you.

 

I generally rule out sensors when a vehicle is running as poorly as yours and not throwing a code for any particular sensor. Sure, it is possible that when a sensor starts to fail and becomes weak, it can gives an intermittent signal that could come up as a generic misfire. With that said, the crankshaft sensor and camshaft sensor generally will cause a no start issue when they fail to protect the engine.

What makes your situation difficult to troubleshoot at this point is that you have already replaced so many parts that leaves little left to be the cause. If it were my vehicle, my attention would be pointing to the ignition wires. My brother's Rav4 had a similar issue after replacing so many parts and doing a full tune-up. After several hours of troubleshooting his vehicle, I narrowed it down to possible bad ignition wires. I went through two brand new sets of ignition wires from Advance Auto without any change. It wasn't until I ran the car in the dark and saw fireworks under the hood everywhere that I realized that even brand new sets of wires can be crap. I went and got Nippon Denso wires from dealer and problem solved. I think that this is a simple place to start and may be your problem even if you purchased new wires. I recommend that you do what I did and run the car in complete darkness and see if you see sparks coming from the spark plug wires and go from there.

 

Thanks. When engine is running and in neutral it runs fine. When I slowly press gasspedal it starts to vibrate at ca 3000 rpm.
What do you think.?

 

I think you should do what I recommended and report back.