Interesting development. As you know from previous situation, I over-washed the engine, took a dive on #3. That straighten out after driving, but ate up a cat on passenger side (I think cat was on the edge anyway and all the precious metal had been turned to a sand -like substance in the cat- very strange). That I found out after having new plugs - mine were pretty carbonized at 75k- of mainly city driving and had the coils on 3 and 5 replaced. Then I knew we need a new cat- got one with new Denso O2 sensors - car ran like a charm.
Been moving- have driven about 1000 miles in last 2 weeks and most at about 70-75 mph. Not a problem one.
Finally got moved and have changed where I have been getting gas (usually only use Shell) and have been getting QT (which is listed as a top tier).

Drove out for a short trip today- came back and then was going out again about an hour after being home - backed out and when I started I could tell I had a rough sound engine and some misfires. Immediately stopped - ran a scan and pulled pending of p0303 and p1316. Thought- OK- have a 2 year warranty on repair work done- so they can fix and that will be that. Of course it has to be a weekend. I was having trouble just sitting in idle with misfire

Finally did get a CEL- same codes. Thought this is too strange and out of no where- so I said - I wonder and stopped by the O"Reilly's nearby and got a can of Seafoam and Lucas octane booster- put in car that had about 10 gallons in it. Drove down the city streets for a few minutes and heard what I thought was pinging from the car, but was not sure- but was some sort of pinging/clicking sound that appeared more when I ran next to parked cars or in between buildings. However the more I drove the smoother it got.

Went down to Freeway- reset codes so I would see if I threw any (pending or solid) (never got any restricted performances). Drove the car for about 30 minutes at 75-95 mph. No problem in power- no problem in sport or regular transmission mode and with AC on. Stepped on passing gear- red-lined as best as I could. After getting off highway, I had no rough idle at stop lights, no misfire when starting off or in driving. Checked codes- showed all but 2 had completed and just the expected P1000. Nothing else. We will see in the morning after it is completely cooled down, but at this point either I had a slightly clogged injector or had some form of bad gas, although I very rarely ever let the tank go below 2/3 full- so it could not have been much. Filled the tank with Shell Prem. after all of this and before I parked it for the night.

Any thoughts, ideas, suggestions or anything else that could have caused this problem or did I stumble on the answer or got lucky. Clearly if have more problems with 3- the mechanic can replace.

When I did set a hard code the freeze frame showed the short term fuel trims at 0.0 (both sides) and long term at about -2.3 on the #3 side. So that said all was normal.

Thanks again- as always

Tom in Dallas
2005 S-Type 3.0 76500 miles


Quick update- went out after writing the above. Still had misfire, but not a severe, pushed it a touch got a flashing CEL- (know what that means) - so the new coil #3 must have gone bad and the mechanic will have a warranty repair.

This was a Jag part coil (although it does look to be slightly different than the original one on the car) Are these coils this sensitive???

 

Went out started car. Zero problem at idle. Drove about 5 miles in combination of city and minor highway driving. Stopped twice turned engine off and back on. No problem. Did not try and push to full load, but got to 75mph without a problem.

So what gives- does this sound like coil #3 is having an intermittent problem or is one coil (new within 3 weeks) actually going bad or is there some other electrical problem that would just give one coil or cylinder a problem and why just #3. Could this be an alternator or battery issue- will test alternator today.

Except for one coil going bad (that was new) I would think a bad battery or alternator would cause other problems as well as other codes.

Help- I am at a loss of ideas except for a new coil going bad!!!

Tom in Dallas
2005 S-Type 3.0 76500

 

I'd do the easy things first. One of them would be to check fuel trims (not expecting anything interesting but it's easy) and swapping #3 coil with any other. I'd also look at freeze frame data in case it nudges any thoughts. And do that a few times to look for any pattern.

 

+1, and lay off the snake oil additives . They will skew the results and will not fix any gas related problems, not that I think this is the case.

 

Have checked fuel trims a few minutes ago. Insignificant on both. When I did set a hard code last night (deliberately) the fuel trims on the right and left side were 0.0 at ST and -2.3 and -4.2 respectively on LT.

Just went out and did idle and 2500 rpm after having driven the car.

At idle- st on both is 0.0 and 0.1 /// -3.1 and -2.3 on lt
at 2551- st is 2.3 and 0.8 /// -6.3 and -2.3 on lt

Tom in Dallas

 

I am usually very hesitant to use any additives, but last night it was just out of whack and decided to try and see- since I have changed gassing habits.

Today the car drives fine, although I have yet to put the most extreme load on it that I can.

Tom in Dallas

 

Well it is coil 3 and swapping is not the easy thing to do , but I had it replaced 3 weeks ago and have a 2 year warranty on parts and labor- so if it goes south again- then they can do it at their cost and time.

Any reason that anyone could think of that the same coil would go bad and the least one may not have been bad, but I replaced it, since I was having the plugs done and had #3 and 5 changed for obvious reasons.

Also checked voltage of battery and alternator and all seems fine.

In reading the forum, I have seen many more problems with #3 on these 3.0 engines than any other. Is there a reason for that?

Tom in Dallas

 

I am sure this is a misbehaving coil #3 that under serious load wants to misfire and then throw p0303 (only one) p1313, p1316- all points to DTC p0300- so a new one we get under warranty and they can live up to it as they should.

Thanks all

Tom in Dallas

 

Tom it is possible that the coil went south in a hurry. Without rereading the whole thread, was it an OEM or aftermarket coil?


Many years ago I replaced all 6 coils in a fellow members '03. The member went the cheap route and purchased coils from Rock Auto. I replaced them and fired the vehicle up. Guess what, #5 was misfiring! I removed the plenum again (this is where I removed the plenum swapped #5 coil) and had vehicle restarted in 15 minutes, yep 15 minutes!!!


I swapped #5 with COP #1 and used an old COP until Rock Auto replaced coil #5 a few days later, free of charge. Anyway you read about it under "2003, 90k, maintenance" or something like that.

 

It just happen out of the blue and the new coil, which the mechanic put in,
was a jag part ( C2S42673).


It gives me, right now a lag and miss when I step up the load at the high end. I drove last night to a friends house about 20 miles, mostly freeway and back again. Never really stepped on it and threw no codes along the way and had it running 80-85 without a problem. However this is some of the same type symptoms I had before where it seemed to run fine at certain points, the you really press it and misfires occur and then I destroyed the cat. I have had only one incident of the flashing CEL (backed of quickly) and while the new cat is under warranty- just don't want to take such time when unnecessary.

It started off much worse and then as I have driven it has gotten better. Very strange.

Is it possible that it could be anything else other than the coil (realistically), when I get no other codes but what I have listed and a very minor rough idle?

Thanks

Tom in Dallas
2005 S-type 3.0 76k