At 11:15 PM 11/1/01 -0500, you wrote:
>Hopefully that'll grab some attention. My engine has always had a
>little bit of a ticking noise to it, but for the last month or so, it's
>been worse. It's rhythmic with engine RPMs (as RPMs go up, the
>frequency goes up). I normally run 87 octane, but Tuesday night filled
>up with 89 and tonight I poured in a 20 oz. bottle of Techron. Doesn't
>seem to be any better yet. I considered that it might be an exhaust
>leak, but it seems to be coming from the engine area.
>When I'm "coasting" I can't really hear it. Under load, I hear it loud
>and clear. Typically accelerating on flats or holding speed uphill.
Use a rubber tube to the ear and to the injectors and see if the
ticking noise from the injectors sound similar to what you hear.
Having someone operating the pedal at different, idle revs would
help. See if the noise is coming from around the area where
the lifters are as well.
The injectors do make a clicking sound when they open and close.
Under certain circumstances, the injectors will stop opening and
closing when decelerating.
OE exhaust manifolds do not usually leak but will make a ticking
sound upon startup when engine is cold. If the leak isn't too large,
the ticking sound will disappear when the exhaust gases get hot
and the metal expands.
>My gas mileage has also been poorer than I think it should be. I'm
>getting 13 MPG *at best* in town, and am hard-pressed to get over 16.5
>at 70-75 MPH. I used to be able to pull 17-18 at those highways speeds.
When put together with the ticking sound (if it's pinging), these symptoms
sure point to a leaking belly pan gasket. Are you experiencing a
more-than-normal oil level drop as well?
What is your mileage? The O2 sensor(s) and its circuitry conditions
could also explain your mileage loss. The sensor gets lazy over
time. Dirt etc. contamination is also a common cause of failure
of the sensor (thinking of the wild things that everyone does with
their trucks at Jon's BBQ).
>Last September (21,000 miles ago), when I was at the dealer for the
>dreaded ping, they replaced the cap, rotors and wires with OEM parts.
>They also re-indexed the distributor, as it was 5 degrees off, and
>flashed the PCM. My Autolite 3923s are about 15 months old (July
>2000). Yes, I'm sure they've been in there too long, though I pulled
>one last summer and it looked good.
Time for replacements.
>At Daktoberfest, Jim Knox thought he heard a misfire when I had it in
>Neutral and got the revs up.
Misfire will cause the O2 sensors to send false readings to the PCM
resulting in increase gas usage as well as dumping raw gas into the
exhaust. Have you smelled any gasoline fumes around the truck?
>2 weeks ago, I pulled the TB and gave it a good cleaning. I did look
>for oil inside the intake manifold, but didn't see a large quantity,
>just a film, which I understand is normal.
>
>So, here's my list of things I'm going to do/replace (hopefully this
>weekend). What else should I put in here?
>Cap
>Rotor
>Wires
>Plugs (3923s again)
>Clean air filter (K&N cone)
As someone already mentioned, replace the PCV valve too.
>Would it be worth pulling and cleaning the fuel injectors? What's the
>procedure for this, and do I need a special socket?
Do you have the url for Jon's MPI installation? The section for removing
the injectors (no special tool required) may be there. If not, let me
know, and I'll copy it from the printed installation guide. The only
messy part if purging the gasoline from the line and the rails.
>I really, really, really do not want to bend over and pay the dealer to
>look at this. I'm well out of warranty at this point. I want to do as
>much as I can myself before resorting to a dealer visit. Is it possible
>that my belly pan gasket is only very slightly leaking, not enough for
>oil to come in? Valve lifters? andy
Do the ignition maintenance first? Maybe try to localize the
ticking location. See what improvements occur and let us know.
Good luck.
Bob
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