SES Light On.... Misfire? [help from the pros please]

[StanF18]

UPDATE 2: OK, spoke to soon

Problem is back. Had another mis-fire at 18 degrees F! The usual shaking and bucking up and down.

Had to turn her off and re-start. She started OK the second time, but now the SES light is lit up all the time. Steady light. How much $$damage$$ are we talking assuming it's the oil separator? Will the $tealer take an arm and a leg?

[anerbe]

^ check my thread - same problem with an 06. 2006 is outside of the SIB for the intermediate levers, but it could still affect ours I guess.

I've been recording on video my cold starts - the car is shaking a bit on startup still, and now there's an irregular idle where the rpms would cycle +/- a few rpm every second, like a dying electric motor with low power. this is all the time. I'm waiting for the CEL to come on before I bring it back in to the dealership.

car also has pretty bad piston slap noise for a good 20 mins after start - told it was normal.

keep us all informed on your status, as I will with mine. I don't think the 04-06 4.4 has oil seperator problems - but it could be one of the hoses.

[StanF18]

OK, I found your other thread on the intermediate levers. Will let you know how things progress.

Piston slap noise? I think I have that too! Is that when you step on the gas abruptly after pulling it out of the driveway, there seems to be a like a "smack" sound coming from somewhere in front? Then you ease up on the gas...then give abrupt gas say 5 seconds later and another "smack".
And it will do this any time you open up the gas, but only when you floor it? It doesn't do it if you just feather the gas. And then 5 minutes into the ride, I can no longer re-create it. The problem goes away. Does that sound right?

[anerbe]

mine did it again - drove the stuttering beast directly to the dealership without restart. I will post my findings on my thread.

piston slap is a noise that sounds like slapping whenever you rev the vehicle. it's more prominent under load, but the car sounds like a 1980 v8 domestic pickup truck. it's not a single event sound. it's cyclic with the engine RPM's. a quick search on the internet could help describe it better.

[StanF18]

OK, dropped her at the dealer today. SA said they'll take a look at the code history, and will also keep her overnight outside to do a cold start tomorrow morning. He said the codes should narrow down whether it's oil separator, intermediate levers, spark plugs, or something else.

Will keep you posted....

[StanF18]

Well, obviously the car started up just fine for them this morning.
SA said they ran the code history, and there were indeed several mis-fires on multiple cylinders. Now, apparently each code has a computerized "test" associated with it and when they hooked the X up to the computer and ran the tests, it passed all of them. Furthermore, SA said there is nothing to indicate either oil separator or vacuum leak issues since there would also be "lean mixture" faults on the codes.

He said the tech's best hunch (and the tech admits it's just a hunch) is spark plugs. The X does have 87,000 miles on it and they usually recommend doing spark plugs at 100,000. He also mentioned that my Dinan mods (specifically the exhaust) may have slightly shortened the life of the spark plugs? Due to the lower air restriction? Can that be? Regardless, I'm going forward with the spark plugs and having them throw in a fuel injector flush at no additional cost.

[m5james]

I find it hard to believe that having aftermarket mufflers would ruin the plugs. If anything, if the mufflers flow free, it should help w/ less carbon fouling.

It sounds like you're having the dealership replace the plugs. If not, you can get NGK Iridiums plugs from Autozone for like $7. There are a few threads of debates about using the factory version vs the aftermarket version...mostly being that the dealership NGK/Bosch platinums last 100k but put out less power, while the aftermarket plugs put out more power at the expense of only last like 60k.

[StanF18]

OK, getting the X back today. Dealer replaced all 8 spark plugs and did the fuel injector flush. They did another cold start this morning, ran smooth as silk (according to SA).