Slight Occasional Miss at Idle

[RCodePaul]

As mentioned in the title the LS has started a slight occasional COP sounding miss at idle. Only at idle, off idle even a couple hundred RPM and there is no miss at all. Replaced the COPs at 90k mi and now at 124k mi. COP miss was more regular and at all RPMs.
Any guesses? Going to a buddy's house to do the scan code but can't until tomorrow.

 

[mikeyswood]

Have you replaced the tensioners?

 

[oddball]

FWIW, I've had idle problems related to MAF sensors in other cars. Since there's not an IAC in Gen 2, a good MAF wash would be my guess. It's a commonly missed maintenance item.

 

[RCodePaul]

Well....

Have you replaced the tensioners?

I replaced the upper tensioners and chains to no avail. I've not replaced the main tensioners yet. Get the brief startup rattle (less than a second) only if I don't let it crank a bit (pull the FP fuse) and it doesn't rattle when warm. Runs normally other than an occasional miss at idle.

FWIW, I've had idle problems related to MAF sensors in other cars. Since there's not an IAC in Gen 2, a good MAF wash would be my guess. It's a commonly missed maintenance item.

Did the MAF wash awhile back when it would start and die.

The codes were 0303 cyl 3 misfire and 0316 engine misfire on startup. Worth a COP on 3 or do the tensioners first? Just hate to dig into this thing that deeply right now. Super busy at work and with kids...

 

[1LoudLS]

Any guesses?

Only one comes to mind.

 

[RCodePaul]

Cop?

I'm not a mind reader but thinking COP. The code fault on cylinder 3 seems pretty solid. My mechanic buddy asked, "isn't ever just a bad plug?" I shrugged, said the COPs seem to be under engineered and are a common fault. Anybody had one go in just 35k miles?

 

[1LoudLS]

but thinking COP.

well over 95% of all engine misses, and "trans slipping" issues are COP related with this car. so its a safe bet that its a good place to start.

with this car, if it smells like a chicken and it clucks like a chicken, it sure as sh!t aint going to make no beef.


on a side note, ive had a coil last less than 5,ooo mi, it was due to an outside factor (water leaking under the cop cover) but i'm sure since this is such a wide spread defect, that many a coil has failed under 35k

 

[RCodePaul]

Oh yeah

I hate to "throw parts at it" so with new COP in hand will swap out the #3 tonight and hope for the best.
The alt going bad was the weirdest alt failure I'd ever experienced and the start/die MAF needing cleaning was right up there as an oddity so hey, 35k out of a $20-$50 COP (cost varies widely depending upon source) may be not so bad.
Unless you are a Camry lover, then that's a whole different yardstick.

 

[RCodePaul]

Sonofab!tch

Well, the OP is the culprit. Did the secondary tensioners awhile back using all new gaskets (kit from Christopher's with all the bits) and guess what I found in the spark plug recess? Effing oil. Those new gaskets were soft as butter, it's astounding they leak. Double checked the cam cover bolt torque and they are tight. Cleaned everything up with brakeclean and clean room wipes, so the head surfaces and the cam cover surfaces were super clean and lint free. I am totally bummed.
WTF???

 

[oddball]

May be worth getting the Ford "improved" replacement gaskets. Always made me wonder what they changed....

Also, that startup rattle might be oil related.... Since the tensioners rely on oil pressure, if there's no oil or the oil holes are slightly clogged (due to improper maintenance), then that could easily cause a brief rattle. Since you've done the secondary, that might point to the primary (assuming the secondary oiling holes looked clean). This is somewhat backed up by saying that cranking (which builds oil pressure) prevents the rattle.
Have different brand oil filters had different effects? I don't know if the engine has a separate anti-drain valve somewhere, but a filter with one might help.

 

[RCodePaul]

Great post

May be worth getting the Ford "improved" replacement gaskets. Always made me wonder what they changed....

Also, that startup rattle might be oil related.... Since the tensioners rely on oil pressure, if there's no oil or the oil holes are slightly clogged (due to improper maintenance), then that could easily cause a brief rattle. Since you've done the secondary, that might point to the primary (assuming the secondary oiling holes looked clean). This is somewhat backed up by saying that cranking (which builds oil pressure) prevents the rattle.
Have different brand oil filters had different effects? I don't know if the engine has a separate anti-drain valve somewhere, but a filter with one might help.

Great post, thanks for taking the time Odd. I will try the improved gaskets, but I tell you, those pieces from Christopher's looked really nice, I'm shocked at the leakage. Shocked.

Startup rattle. I tried several different oil filters, Wix, Napa Gold, Motorcraft from the stealership, all hoping for an easy solution (before the upper tensioners.) The maintenance question is valid, but since this has been 100% synthetics all its life, it's clean as a whistle inside. Mobile 1 full synthetic since I've owned it. Really clean. When I take it apart next I will shoot photos. Very clean, almost no varnish at all, no deposits whatsoever. The perfectly good secondary tensioners were super clean. Like inside of a transmission clean.
I'm frustrated as can be.
When I was younger at this point I'd be cussing and throwing stuff.

????

 

[oddball]

FWIW, my "improved" ford gasket is leaking on the lower rear corner of the passenger head. At least that's the easy one to get to, but the burning oil is right next to the air inlet. So the air smells like burning oil occasionally.

These days I just do a big sigh and open the beer fridge when it gets to "that point".