zze86

Just back from a drive where the CEL came on. 2nd time car has been out this season, no work done to the car over winter or last season either really. As I was going through an intersection a large cargo truck passed me going the other way and it sounded like something fell from the car, a PING! like metal hitting the ground. My car or the truck I'm not sure. Maybe a mile down the road I get some major hesitation and general lack of power with a slight smell, possibly unburnt fuel. CEL comes on almost immediately after the hesitation starts. I pull over when I get the chance to inspect the car and everything looks OK. Limp it home, ~5 miles, and pull the codes:

P0300 - random misfire
P0302 - Cyl2 random misfire
P0303 - Cyl3 random misfire
P1399 - pending misfire

I don't have time currently to diagnose further and I was going to tackle a number of maintenance items this weekend anyways: VC repaint, VC/spark plug tube gaskets, spark plugs, valve adjustment but how worried do I have to be that something actually fell off the car? I've floated the idea of combing the rather busy intersection for anything weird, lol. Just coincidence? Anything that could physically fall off the car that would create these issues?

B serious

Check your spark plugs. If they haven't been torqued to the new spec (22LB or something), one may have popped out.

I originally checked mine around when I bought my car. All of them were looser than finger tight. Probably like 2 turns from even being seated on the head. Scary stuff, that.

zze86

Hoo-whee! April was crazy for my family and a bit of mission creep as well so I JUST got done working on the S. Unfortunately, I could tell immediately during start up that she wasn't good, stumbling idle. CEL came on after maybe 5mins, code was a P1399. So here's what I done:

1. Disconnected battery, pulled plugs and valve cover.
2. Plugs were still on tight and looked real good actually but I figured may as well replace them since I wasn't sure how old they were, so a new set of NGK 7746 IFR7G-11KS were thrown in.
3. Adjusted valves to the looser end of the spectrum (0.25mmIN, 0.29mmEX). 5 of 8 exhaust needed adjustment and only two were real tight. 2 on the Intake side were tight maybe (my gauges were in 0.05mm increments) while the rest were within tolerances. (which reminds me I need to start a thread on my retainers)
4. Painted VC, new OEM gasket kit put on and buttoned her up. New air filter. Changed oil, trans and diff fluids. <- all looked real good. Not sure if PO had changed them and just didn't include them in his records.
5. I had marked the coils prior to taking off the VC and was planning on swapping them around to see if the cylinder misfires changed but thought I should try with them in their original placement first.
6. Started her up and she was stumbling immediately, then CEL after 5 min as previously noted. Checked the code and at least the cylinder specific codes are gone. Just the rather unhelpful P1399 - Random misfire code. So maybe not the coils....?
7. Erased the code and started her back up. Stumbling and CEL comes back on. Check the code and I get P1399 and P1410 - Secondary Air pump malfunction. Weird.
8. So I erase the codes and started her back up again, stumbling and CEL comes back on. Check the code and I get P1399 only.

OK, probably the misfiring confused the system and threw out the P1410 cause I don't see how that effects the misfiring. So next plan of attack is to throw in some fuel system cleaner/octane booster and see if that clears it up. Maybe I got a bad batch of gas. Then move to coils, then injectors.

That sound about right, ya'll?

Unfortunately, the next update may take me a while again....life beckons...

***EDIT*** Forgot to ask since it's been a while since I drove the car. When turning the key to ACC after a few seconds, the immobolizer light goes off, but my EPS light remained on. Goes off with the car running. Is the EPS light on normal? I just can't recall anymore.

engifineer

If there is something wrong with the air pump system that is causing a vacuum leak, that could cause misfires as well.

Make sure the vac lines for the air pump are connected properly. There is one near the front of the valve cover (connected to the metal tube assembly) that people many times leave off accidentally and sometimes it looks like it is in place, but actually is right beside the tube it connects to.

Chuck S

EPS light remains On in my '06 until I start the engine.

-- Chuck

zze86

Thanks for the confirmation!

zze86

Checked and it looks good. Thanks for the heads up though!

zze86

Just wanted to follow up for future reference.

Added some fuel injector cleaner/octane booster and drove for a couple of miles. No change.

Based on some research on how misfires are detected by OBDII systems in general, the most common method is to monitor crank speed. When a cylinder fires, the crank should speed up momentarily. In combination with the firing order, the ECU can determine which cylinder is misfiring if it doesn't see this momentary speed-up. As you can imagine this may not be the most accurate method. If the speed-up pulses are hard for the system to sense it'll just throw the generic P1399.

So I was guessing that coils 2 and 3 could both be intermittently going bad or one of the two was intermittently bad but good enough to confuse the system as to which one exactly, especially since they fire next to each other.

SInce I don't have a way to test the coils and the rando CEL P1399 was no help I just went ahead and ordered four new coils.

Replaced one-by-one so I'd know which one(s) were bad. Started with coil 2 based on the initial CELs and...no more CEL, smooth!

Replaced all coils for good measure so now I have three spares.

boyguan

Thanks for the follow up.