Knock codes were setting, then I got caught up preparing for a
trip and let the oil run low, causing the timing chain guides to wear,
thenceforth there was guide noise. I had previously used Restore and
that buildup on the valves wrecked the valve seals. My mpg went up to
29 as the computer tried to compensate for oil from the head going out
the exhaust. Naturally there was a ping code. It had a new catalytic
converter and all else seemed fine. I was going to have the head
changed but was advised by the mechanic to go with a used engine. He
said he could get one with only had 60,000 miles. Then after he had
the car a month he said he couldn't get that engine but got another, a
90,000 mile engine that was suppose to be good and said it was 2 years
newer than mine. I accepted. That engine turns out to be from an
earlier year (the valve cover breather hose is at 90=B0 from the '95 and
a '91 I think it was at the junk yard was identical to that which he
put in). My loss. The ping code sets along with the EGR solenoid
valve code (3-4 and 10-5). I got under the car tonight and finally
physically looked at the knock sensor. I can't say when it happened
but although the Haynes manual says it gets a white wire and is
grounded, the harness has both a white and what looks to be a brown
wire But the brown wire is cut. Not just cut but cut right to the
quick on the plug making a splice impossible. This engine gets a
stable 26 mpg so I don't think a great deal of carbon is going out the
exhaust. I use cheap gas. I swapped the EGR valve from the earlier
engine as it hadn't been setting any codes but the EGR code still
sets.
I see online that the analog filtering used in pre-2000 Altima's
isn't very good and will set a ping code from other noise -- valve
train or I suppose timing chain. The codes set if I run the car for
some distance, turn it off, wait not overly long (not cooled down),
then start and accelerate normally.
So, I have three questions:
a) Is the brown wire to the knock sensor critical?
b) Will an ECM from a 2000 or later Altima drop right in? I
understand that from 2000 on the knock sensor is digitally converted
and goes through a complex calculation to differentiate knock from
other noise. Since the fuel isn't leaned down to a degree that can
produce 29 mpg I'm hoping it isn't ping. My present ECM has a minor
problem. The rheostat that used as a simple debounce circuit has lost
its stops and one must feel carefully for the rheostat start and stop
when checking or resetting codes. If a 2000 ECM would fit in I'd give
a go.
c) If I obtain a knock sensor from a junker along with its harness,
splice some length to the wires, and remount the knock sensor distant
from the timing chain and power steering pump, say near the
distributor, will I see any improvement?
Thanks for your interest and advice.
Bill
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