Is my coil bad?

I know from a diagnostic test that the coil pack for cylinder #5 is bad and needs to be replaced. Where is #5? Is it in the back row of cylinders facing the firewall or is it in front? Can you tell me the location of all the cylinders - if it is in the back row, I'll probably just get all the coil packs replaced in that row since it is so hard to get to.

Thank you!

-Jim

Thanks Jack!

Six cylinder two wheel drive automatic 68,000 miles.

I am helping a friend replace spark plugs and coil packs on his car The front three are very easy to change. The rear three are underneath the intake plenum. I assume the intake plenum needs to be removed in order to gain access to the coil packs/plugs? Is there anything I should know before I remove it? Can the intake plenum gaskets be reused or do they need to be replaced?

I have worked on cars for many years, mainly Honda's, but I am not a professional mechanic. Everytime I have to help a friend on a Ford/Mazda I cringe.

Here are my results:
Yes, the upper intake plenum needs to be removed. There are six bolts that hold the upper plenum to the lower. Those are very easy to remove. There are also two brackets with bolts, one on the right side and one against the firewall, that need to be removed. Before you remove the bolts you have to remove everything from the plenum. The EGR valve, intake tube, a bunch of vacuum hoses, wires, etc. I removed the cruise control on the upper left side of the engine compartment to gain more room to reach the back of the plenum. After everything is off you can pull the upper plenum off the lower. Pull it up and forward a bit so you can disconnect the two vacuum lines that attach to the back of the plenum. After that it will be free to come out. Once that is done changing the plugs and coil packs is very easy.

Reassembly is fairly easy but the vacuum lines under the throttle body can be tricky to oraganize. Take your time and you will figure it out. I reused all the gaskets and so far no leaks.

I did find another major problem once I remove the plenum. The large vacuum hose that connects to the back of the plenum had collapsed, melted and had two holes in it! I picked up a new hose from a local Mazda dealer. They informed me that that hose is a known problem with the MPV. The new hose is much thicker and stronger where the previous one had failed.

Anyway, the car now runs better than it ever has according to my friend. I assume the misfire problem was probably caused by the blown vacuum line not the coil packs/plugs. We still changed them since we already had everything apart.

Engine Performance problem
2004 Mazda MPV 6 cyl Two Wheel Drive Automatic

In the past 4 months my van has been in the shop 6 times for coil replacements. They keep telling me this is a common problem and they are like light bulbs. They frequently can go out. But I can't pay $180 every time my car needs a new coil. I took it in last week for a coil, and it started doing the same thing again 5 days later. They tell me it is a different coil this time. Is this common? Why has this NEVER happened on any other car I have owned?

Mine also does this. Mine is a 2004 with 100,000 miles. It seems to start missing after a heavy rain. Does this seem to be your case? My husband replaced mine, though, not the mechanic. The coil cost about $90. It's not very easy to get to the coils, though.

I just spoke to the dealership again today. They said once again that it is probably another coil going bad. Yes, mine started doing this again everytime it rains. The dealership acts like this is common and tells me these things go out frequently and don't have any expected life span. They are electrical and can go out whenever. I just think it is a Mazda thing. I will never buy a Mazda again. I have driven other cars for 150,000 miles for 8 years and never had a coil go out. Especially 5 coils within 39,000. Since my van only has 6 coils, I figure I should only have one more to go before they have all been replaced. Then, I expect them to last another 40,000. Like that will ever happen.

Did you ask the dealership why it seems to do it after it rains? That doesn't make sense to me. Mine is sitting still now, because it's acting up. It's been raining for several days, I cranked it yesterday to go into town, and it started missing before I ever put it into gear. Very strange.

Does my 2001 Mazda MPV have a distributor, or does an ignition coil perform the same duty?

The dealership said that it is another coil getting ready to go out and you will start to notice this more when it rains. When I start my van while it is raining, it will start to shake a little and then the engine light comes on. It is still driveable, it just shakes a little. The next time I start it, if it is not raining, the engine light will still be on, but it will run fine. The next day, without rain, it will run fine and the light will go off. They act like I am crazy and I should understand how this is common.