Recent coil/misfire problems
 

About two weeks ago I started getting the SES light. I had noticed that it was missing a little when started cold, I figured that was what was tripping the light. Foxwell told me it was cylinders 2+3 acting up. It always smoothed out after running a minute or so. Last week it was taking more time to run on all six, sometimes a couple miles. So I bought two coils and replaced 2+3. Put in a new battery about this time also. I should point out that the plugs were done about 6 weeks ago with iridiums. The new coils initially seemed to fix it, for a day or two anyway. Today when started to come home from work (a 40 mile trip) it was rough again and the SES came back. I drove it home but noted rough running most of the trip. When about 30 miles into the commute it smoothed out and began running smoothly on all six. When I got home Foxwell told me I had misfires on cylinders 3,4,5+6! These must have been intermittant as It wouldn't run on just two! So what I have done is swapped coils 1+3 with each other. #1 has never misfired according to the scanner, so now we'll see if the miss follows the coil or not. If the skip stays in cylinder 3 (with the known good coil) where do I go? Look at injectors? I only run premium and now it has a can of Seafoam in it. I'll report how it runs tomorrow morning with another cold start and 40 mile drive. TIA

Seafoam is way way overrated IMO. It's just a bottle of light oil carrier/light solvents....IMO. I think Amsoil is a good flush, but even that, just run it for 15 min and dump it out

Todays cold start yielded a single cylinder misfire, definetly not two or three. I let it idle and it cleared up and ran smoothly in less than a minute and was fine for my entire commute. It did not trip the SES light. After swapping 1+3 coils yesterday, this tells me it was probably cylinder 1 that misfired. I will pull the codes at lunch and see if I have a pending code for the misfire. If no pending code, I'm not sure what I'll do. :dunno: Suggestions welcomed.

The STRANGEST thing just happened. Started the X to go to lunch. As usual it started with a miss, and tripped the SES. Drove it about 3 miles and parked. While parked I decided to clear the codes. Foxwell said cylinders 3,4 and 5 were at fault. I let it run while I cleared the codes and heres the weird part, the instant the codes cleared so did the miss! Normally I would chalk that up to coincidence but this is the second time in as many days it has happened. WHAT is going on? Why would/could clearing a code rectify a misfiring cylinder? :dunno:

If the DME picks up a bad enough problem with a cylinder it can cut fuel to that cylinder cutting it out completely for emmissions reasons. When you clear the code it resets that process.

Not familiar with the 3.0i but if it has it check the plug on the valvetronic is not loose

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What could be a significant enough problem? It runs great after the codes are cleared. The problem starts with a cold start, every day now it is a lumpy idle in the morning. Some days take longer to smooth out than others. Is the timing or duration of the injection pulse different when cold? I would assume so. What "controls" the injectors? The DME? Should I search for pending codes elsewhere? If so, where? Should I have done anything when I installed the new coils or battery? TIA

That sounds like a good idea but I have no clue where that plug would be on the 3.0i...:dunno: I'll look at the parts diagrams and see if I can figure it out. Thanks

This is where you need to start, concentrate on diagnosing the rough idle at start up. Not sure about the Foxwell scanner though.

I'm beginning to doubt my coil diagnosis. They may not have been the problems afterall. I guess now I look at the injectors (something I know even less about). One encouraging note, this mornings cold start, although it did stumble a little, it smoothed out quickly (~30 sec.) and didn't trip the SES light.
I'll pull the codes and see if I have a pending misfire code.

Would a misfire due to a poorly operating injector be enough for the DME to shut that cylinder down? I did run a can of Seafoam through this last tank, maybe it actually helped and that's why it didn't act so poorly this morning.

Thanks for the help, I need it! :dunno: