BigChief5890

Hey guys! I recently changed my spark plugs because I was getting close to 80k miles on my car. I just put in the Motorcraft OEM spark plugs. After completion, my car started backfiring and missing. I checked the Coil Packs to make sure they were plugged in good any everything. I took out the spark plugs and they were wet so I cleaned them off and installed again.. Thinking maybe I forgot something. When I tried to start it, it would turn over but just not start. I checked the spark plugs and they were fouled. I put the originals back in and ran the car and it drove fine. I waited about an hour and went to drive it again and it's backfiring and missing again. I'm at a loss. Don't even know where to start now. Any suggestions or anyone have anything similar

m05fastbackGT

Being as your car is now 11 years old and also has 80k miles on her ! I would also change the coil boots and possibly the coils themselves, as the slightest crack in the boots can also cause misfire issues as well..

This would seem more than likely your problem, as the misfire issues came back even after reinstalling your original plugs..

In addition, I would also have your fuel injectors checked and change your fuel filter if you haven't already done so..

BigChief5890

Well I finally got some codes. P0155, P0171, P0301, P0316, P0351. I have new coil packs coming. I'm thinking I need to remove my injectors and ohm them out and see if they are good. I thought about ordering a rebuild kit for them and replace the O rings on them. I have a fuel filter that I will put on too.

houtex

o.0

That is a *ton* to have going wrong with just a spark plug change. Wow.

First, the left (driver's) side of the engine:
P0155 is Bank 2 sensor 1 HEGO sensor malfunction. Either the thing got disconnected or it amazingly went bad after the spark plug change. Bank 2 means the side of the engine that does NOT have cylinder 1. Which is the left side, cylinders 5-8, drivers' side, and it's the first sensor in the exhaust pipes. You can find videos on that one code alone, it seems to be somewhat common-ish. It's probably the actual sensor that'll need replacing. It happens. Still oddly coincidental, though.

The rest are all on the right (passenger's) side of the engine:
P0171 is Bank 1 (Passenger side) is leaned out. (too much oxygen in the exhaust)
P0301 is Cylinder one misfire. Spark's not working on that cylinder.
P0316 is the general misfire detection code. P0301 caused that.
P0351 is Coil number 1 circuit malfunction.

Now, with all that talked out by me, for me, here... Your COP #1 isn't working. Which would in fact cause all four codes. P171 is caused by the unburnt oxygen in the exhaust, seeing as cylinder 1 didn't fire off.

Clear the codes, swap out COP 1 with COP2, and see if code P302 shows up. If it does, then you know which COP isn't good, and can just swap it out (although I read you'll be getting them all swapped, so that'll be that I suppose.)

If it doesn't, and if the codes magically go away, then the connections were the problem all along, and now you're good.

If code P301 shows up instead, then the wiring TO COP 1 is suspect. Bad/loose connector maybe. I've heard tell that a good idea is to stick the harness connector on the COP, then use tiny zip ties to keep them there, lest they fall off (because brittle and the keeper tabs break off, so they might not 'stick'.)

Dunno if I helped or not, but that's my diagnosis. I do not think it's your injectors at all, these all seem symptomatic of COP and a bad sensor. The HEGO, btw, will not cause the bad running. Cylinder 1 COP will do that all on it's own. Car might not get as good mileage, and the CEL will be on, but the engine should run pretty well otherwise.

Good luck, man!

BigChief5890

The P0155 has shown up before. I was just letting it ride for now. The others were all after the spark plug change. I should get the Cops tomorrow. I'm hoping to have it fixed soon. Appreciate the help guys!