Beer Dave

I haven't done a motorvac on my car, however as I was researching the problems I was having the symptoms were pointing in that direction. Turns out I had a faulty coil on one of my plugs. I recommend you read the forums and search for motorvac service. From what I have seen this is a common issue for people with hesitation and idling problems. My understanding is the motorvac service cleans out the throttle body and associated components, but I don't believe it does anything to the injectors. Based upon other posts in the forum it appears that shops that offer this service charge $100-$120. Good luck.

If you aren't getting a check engine light, you might want to look into a Motorvac service. Do a search on the forums for more details.

Update: Replaced bad coil that was misfiring on #6 and problem solved. When I relocated the coil from cylinder #5 to another cylinder to test I didn't get any more misfires from that coil. All I can think is that with #6 being just opposite of #5 it was causing random misfires not related to the coil?? Anyway, thanks to all for the feedback I appreciate it. Only $90 for the new coil, which is a heck of a lot cheaper than if I had taken it to the dealer. SK - just an FYI, mine has a separate coil on each plug. They must have changed them on the earlier or later models.

Blake, Thanks for the feedback, new plugs and wires are definitely on the agenda. I had to drive the car to work last couple of days and will need to drive to the parts store. I certainly don't want to have to replace the cat converter. Any idea how much driving with CEL flashing can cause significant damage to the cat converter? Dave

Mehullica, I don't know why I didn't think of that before. I just swapped #2 and #6 coils, reset the ECU and ran until the code came back. Now #2 is misfiring. #5 came on a little later after I reset from the O2 sensor change, but hasn't come back after my quick drive around the neighborhood. What are the chances two separate coils go out at the same time?? Anyway, I will swap #5 out tomorrow and see if I see anything else. Thanks for the feedback. I will report back my results tomorrow. Dave

I have a '99 ES 300 and it also say 87 octane is fine. But I have noticed that when I use premium I get about 30 miles per tank of gas or almost 10% increase in mileage. Since premium costs about 10% higher than regular your paying about the same amount. At least that has been my experience. Also lots of posts showing O2 sensors, etc. lasting longer using premium.

This is a follow up to an earlier question I had. Here's the background: Had the CEL (flashing) & Trac off lights come on with multiple codes for O2 sensors and random cylinder misfiring. I replaced the O2 sensors and reset the trouble codes, thinking possibly a bad signal from the sensors were causing the misfire (now I think it was probably just the opposite). Yesterday the CEL only came on flashing again and the code showed only cylinder 6 misfiring. I had a post yesterday asking the orientation of the cylinders as I guessed it was either a bad coil or plug. Started the car this morning and the flashing CEL and the Trac off light came back on. Trouble codes now showing misfiring on cylinders 5 & 6. By the way, it is misfiring at idle and all speeds. Car has 95K miles and original plugs and wires. As there is a separate coil for each cylinder, I am guessing that it is not the plugs or the coils?? (although the plugs are due) Reviewing the forums I have seen some suggestions that the cylinder head water temperature sensor may cause misfire problems, however it wasn't clear if there were separate sensors for each pair of cylinders or not? To be honest, I am not even sure what the or those sensors look like or where they are located. I have been fortunate not to have any problems with the car until recently so I just learning my way around this engine. Can anyone let me know if I am on the right track or suggest another possible problem. If I am on the right track I would appreciate some info on the temp sensors.

Steviej, Thanks for the quick feedback. I was guessing it was flipped, with 6 in the back. I was dreading pulling every plug until I had time to do them all. This site rocks! Dave

I have a 1999 ES 300 and am getting a P0306 code (Cyl 6 misfire). I have done quite a bit of research through the forum and realize that it is likely a bad spark plug or coil for cylinder #6. I have found the info on the web on how to test the coils, but I have not been able to find the cylinder orientation (i.e. which one is cylinder #6?) Can anyone point me to a diagram, layout, etc?