I'm working on an '04 x type 2.5 liter. I have recently replaced all plugs and coil packs. Car ran pretty smooth for a few hours and started loosing power and stuttering, wont go over 3k on the tach and the engine light starts flashing. I'm aware that is bad, cat damage. I bought a code reader and it came back with 0300-0304, 0352, 1316, 1314, and 1313. any thoughts on where to start diagnosis? i have to do this on my own, there are no shows in town that will work on the car. Nearest place is over an hour away.

 

Might be worth checking your battery/alternator cables etc, look for discolouration in the copper cause by overheating. Check voltage drop (under load / hot) with a multimeter.

Look for posts by "Thermo" he is a guru in this matter.

If you cables are original...they will need replaced with thicker ones anyway. Factory ones sucked. Once I replaced my one that connected under fuse box, so many other problems went away.

May/may not be the cause of your issues, but needs done on that car anyway.

 

monkeyman, based on what you are describing, I see 3 possibilities. The most likely one is having some sort of fluid in your plug wells. Did you happen to drive through a rain storm? Did you try and clean the engine bay and spray the top of the motor? I would pull the coil off of the cylinder right behind the passenger side headlight and see if you spot oil and/or water in the plug well. If you spot oil, then you need to redo the valve cover gasket on both the front and rear heads (not a hard job, but not something that is done in 10 minutes). After that, I would be checking the coil ground wires. They mount to the side of the head, right behind the passenger headlight. Make sure these terminals are shiny silver and so is the spot on the engine where they get mounted. After that, I would be looking at your fuel injector harness. This can be replaced with relative ease, just have to remove the intake which is what will take up most of your time. If you are in to the car that far, this would be a good time to replace the spark plugs if you don't know when they were last done or it has been 50K+ miles.

 

If you want to check the battery cables, this is easy. Let the car sit over night (want the entire engine bay as cool as possible). Now, start the car and turn on the headlights, A/C on max, dash fan on max, seat heaters and rear defroster. Let the car run this way for 5-10 minutes. At the end of the time, turn off these items and shutdown the car. Open the hood/bonnet and cup your hand OVER!!!!! each of the battery terminals. Are these about the same temp as the other metal parts under the hood/bonnet or is this something that you think you could fry an egg on (hence why you cup your hand OVER them). If they are hot, then you have a bad battery cable. If they are fairly normal in temp, then they are not your problem.

 

Thanks Thermo, for responding. I jumped back under the hood today and took the intake off again. I had replaced all the plugs and coils a few weeks ago. I found that one of the spark plugs had not been tightened down properly and had come loose. Another cylinder had a faulty boot on the coil, when I tried to remove it for inspection is tore in half. I replaced it with a new coil pack and put everything back together. The car is running flawless again. I hooked up the code reader and cleared all old codes, check engine light is off now. In the end it was something super simple that I had over looked.