Ok guys, been a while, looking for some thoughts as I try to chase down a few demons.

1st things first, Merry Xmas and Happy New Year! Hope everyone else's Cats are doing better than mine.

Next - I have an '03 STR, mileage is ~128k, within last 6 months I've done a lot of work chasing coolant leaks, replacing belts, hoses, including the lovely line under the blower. Also at this time, all spark plugs were replaced with NGK. Since that time, things have been going fine - until the last week.

Started running a bit lumpy, and threw a check engine light, pulled the code at that time and got the P0171 and P0174, Bank 1 and Bank 2 lean...suspected an intake leak of some sort, did not have time to chase it immediately. Continued driving ~5 days in this condition.

2 days ago, started running reallllllly rough, and as I suspected, added a misfire code, P0308, as well as P1314 misfire rate cat damage bank 2; P1316 misfire excess emissions; and P0358 Ignition module circuit malfunction, the other P0171 and 174 remained as well. All of this business, parked the car - immediately.

So, I replaced coil #8, as I've been through this drill previously 2 times. I expected similar results, with the misfire being eliminated, leaving my lean codes to chase down. Unfortunately, this time, my misfire stayed, and stayed on #8, with the new coil installed. Note, when installing the coils, I typically hit the coil boot with a fair bit of die electric grease, as well as the connectors at the coil plug end.

My questions for the group are as follows:
1) It feels like an electrical issue at #8 to me, and I'm wondering if there is a way to check/verify that my wireharness is functioning as appropriate? A continuity test of some nature, or a 4 pin light that I can plug into the harness at coil #8?
(schnikeys, just found the pin out section in the JTIS disc, see #3)

2) If the #8 coil plug/harness check out ok, what am I left with, ECM or ignition modules? If so, how do I verify where the issue actually resides in these components? Would a ignition module crap out on 1 cylinder and not 4?
(schnikeys, just found the pin out section in the JTIS disc, see #3)

3) As always, other thoughts recommendations much appreciated.

P0171
P0174
P0308
P0358
P1314
P1316

Thanks for any help in advance, and kind regards

joe

 

its a possibility the plug has failed, i'd replace the plug and swap the coil with another one and see if the misfire moves

 

That is a GOOD explanation of things, THANKS HEAPS.

I have NO idea of this, but being "old", me not the car, I would change the plugs, or at least #8. Just "back to basics" thinking on my part.

I have used NGK for eons, and never had an issue until the freeby Platinum in the X300, I know different technology, but not a nice running engine at all. Sweet as, for about 6 weeks, then "off the boil", and simply putting the old scungy plugs back in sorted it.

Some other genius will have more info soon I hope.

 

Need car details! It must be a V8 but which? See below.

I hope it's not a 4.0

 

[QUOTE=jar;647947.

Next - I have an '03 STR, mileage is ~128k,

joe[/QUOTE]

 

Oh, sorry.

Maybe identified the wrong cyl as #8 or put in a bad coil. Swap with one that works, maybe. (And/or buy a COP tester.)

Were the plugs cthanged at 100K as per schedule?

I don't understand the talk of 1 & 4. Explain please. No... I got it. See next:

Also, what ignition module(s)? There aren't any (other than PCM and the coils).

JTIS explains the subsystem and identifies all its parts plus as you found how to test wiring etc, with pin #s.

 

Another suggestion - check to ensure the connector to the fuel injector to Cyl #8 is nice and snug - a loose or intermittient connection will throw a misfore code, etc. While your at it - check all the fuel injector connectors - Good Luck!