Engine Knocking - Additional Information

Here r some details my husband omitted.
1. The first reading of computer showed 2 codes. One for cylinder 3
and one for cylinder 4 missfiring but "check engine light" never
stayed on-just flashes when problem (knocking) occurs then goes off.
Mechanic replaced all sparkplugs, problem continued. Mechanic replaced
#3 coil, added premium gas, and Techron, problem mildly reoccurs
intermittently, with "check engine light" flashing, then going out.
Brought back to mechanic after coil changed and computer reading
showing #3 cylinder missfiring even though that was corrected. All
else appears normal in car when happening, temp guage fine, Also when
knocking, missing, etc., the "check engine light" flashes on and off,
but does not stay on. Problem is intermittent, generally happens at
speeds over 55mph, then gives smooth ride. Afraid to use for long
distance driving at this point. Sometimes smoke pours out of exhaust
when knocking, other times doesn't do it. Prior to any problems, oil &
filter was changed about 5 days before, and valve cover replaced on
same day.

iconlarry > wrote:
> Prior to any problems, oil &
>filter was changed about 5 days before, and valve cover replaced on
>same day.

There's a big red flag right there. Why was the valve cover replaced?
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Apr 10, 5:54*pm, (Scott Dorsey) wrote:
> iconlarry > wrote:
> > Prior to any problems, oil &
> >filter was changed about 5 days before, and valve cover replaced on
> >same day.
>
> There's a big red flag right there. *Why was the valve cover replaced?
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

IN late January, I started to smell an oily/smokey like smell inside
the car while driving it, of course not regularly, but enuf to want to
bring it in and have it checked. Mechanic said gasket needed to be
replaced. But fine to drive until repaired. Basically it stopped doing
it, and I brought the car in when the weather got a bit better here on
March 18. On that date I had the oil and filter changed it was about
40 miles overdue, receipt reads 4 qts. 10w 40 oil, and the valve
cover gasket was replaced on that day.

On April 4th, brought car in for: loud knocking, kind of bucking,
engine light flashing on and off, only on highway, local driving no
sign of problem. Mecanic read pending codes misfire of # 3 & 4
cylinders. Replaced all spark plugs. After sparkplug replacement still
had flashing "check engine light", code read misfire #3. So had #3
coil replaced next day, tested, still knocked but much more gently,
flashing light when knocking only, code reads misfire #3 same as
before. So from March 14 to April 5 recap:
oil change 4 qt.
oil filter change
Replace valve cover gasket
new spark plugs
replace #3 cylinder coil
had front brake pads & rotors replaced (very necessary) I was aware of
brake grinding, rust, etc. had a few hundred miles to go, but had work
done-car was also due for inspection in April.
car idles soundlessly. Any leads you may supply would be appreciated.
Thanks again.

"iconlarry" > wrote in message news:58129cca-On April 4th,
brought car in for: loud knocking, kind of bucking,
engine light flashing on and off, only on highway, local driving no
sign of problem. Mecanic read pending codes misfire of # 3 & 4
cylinders. Replaced all spark plugs. After sparkplug replacement still
had flashing "check engine light", code read misfire #3. So had #3
coil replaced next day, tested, still knocked but much more gently,
flashing light when knocking only, code reads misfire #3 same as
before.


Misfire messages can mean bad spark plugs, bad plug wires, dinternal
short in distributor if it has one, bad coil or ignition unit, blown head
gasket, cracked head, and perhaps others.

It could be bad, or not. You have to work through the possibilities
carefully. Trouble shooting, not parts replacement, is the better way to
go usually.

On Sun, 10 Apr 2011 16:32:50 -0700 (PDT), iconlarry
> wrote:

>On Apr 10, 5:54*pm, (Scott Dorsey) wrote:
>> iconlarry > wrote:
>> > Prior to any problems, oil &
>> >filter was changed about 5 days before, and valve cover replaced on
>> >same day.
>>
>> There's a big red flag right there. *Why was the valve cover replaced?
>> --scott
>>
>> --
>> "C'est un Nagra. C'est suisse, et tres, tres precis."
>
>IN late January, I started to smell an oily/smokey like smell inside
>the car while driving it, of course not regularly, but enuf to want to
>bring it in and have it checked. Mechanic said gasket needed to be
>replaced. But fine to drive until repaired. Basically it stopped doing
>it, and I brought the car in when the weather got a bit better here on
>March 18. On that date I had the oil and filter changed it was about
>40 miles overdue, receipt reads 4 qts. 10w 40 oil, and the valve
>cover gasket was replaced on that day.
>
>On April 4th, brought car in for: loud knocking, kind of bucking,
>engine light flashing on and off, only on highway, local driving no
>sign of problem. Mecanic read pending codes misfire of # 3 & 4
>cylinders. Replaced all spark plugs. After sparkplug replacement still
>had flashing "check engine light", code read misfire #3. So had #3
>coil replaced next day, tested, still knocked but much more gently,
>flashing light when knocking only, code reads misfire #3 same as
>before. So from March 14 to April 5 recap:
>oil change 4 qt.
>oil filter change
>Replace valve cover gasket
>new spark plugs
>replace #3 cylinder coil
>had front brake pads & rotors replaced (very necessary) I was aware of
>brake grinding, rust, etc. had a few hundred miles to go, but had work
>done-car was also due for inspection in April.
>car idles soundlessly. Any leads you may supply would be appreciated.
>Thanks again.

Sounds like a dirty valve problem to me, or a broken spark plug wire,
or a fuel delivery problem...or cylinder #3 isn't getting proper
compression during firing cycle. (intake-exhaust valves for cylinder
3 not seating fully with block).

Replace spark plug wire.

Get 1/2 tank gas, add 1 bottle GUMOUT =and= 1 bottle TECHRON. Run
until near empty.

Put full synthetic oil in engine and let that remove engine deposits,
while Techron and Gumout goes after fuel delivery system. Get Techron
FUEL SYSTEM CLEANER, nothing else, except for hi-concentrate GUMOUT.

I had this problem, and solved it myself.

Lg

iconlarry > wrote:
>
>IN late January, I started to smell an oily/smokey like smell inside
>the car while driving it, of course not regularly, but enuf to want to
>bring it in and have it checked. Mechanic said gasket needed to be
>replaced. But fine to drive until repaired. Basically it stopped doing
>it, and I brought the car in when the weather got a bit better here on
>March 18. On that date I had the oil and filter changed it was about
>40 miles overdue, receipt reads 4 qts. 10w 40 oil, and the valve
>cover gasket was replaced on that day.
>
>On April 4th, brought car in for: loud knocking, kind of bucking,
>engine light flashing on and off, only on highway, local driving no
>sign of problem. Mecanic read pending codes misfire of # 3 & 4
>cylinders. Replaced all spark plugs. After sparkplug replacement still
>had flashing "check engine light", code read misfire #3. So had #3
>coil replaced next day, tested, still knocked but much more gently,
>flashing light when knocking only, code reads misfire #3 same as
>before.

I'm not suggesting anything. There are a lot of things that could be
causing your problem. But just to let you know: if someone had left
a socket wrench inside when they closed up the valve cover, it would
probably have symptoms like you describe.

Whatever the problem is, the computer codes are indicating an ignition
problem, but in fact the ignition issue might be a symptom and not the
actual problem.

If it were me, I'd pop the valve cover and check the lifters myself.
I'd also pull the plugs on the cylinders producing the errors and
verify by eye that they have a nice hot spark.

Intermittent problems are no fun for anyone, because as soon as you
start looking for them they go away and then they come back when you
aren't prepared to look any more.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."