Spark Knock

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Forwarded message:
Subj:    1994 4wd extra cab 4cyl.
Date:    97-04-09 15:12:28 EDT
From:    AThorn5556
To:      toyx4@winternet.com

Dear Minnesota,

I was wondering if any of your members  have any experence with a 4 cylinder
engine that spark knocks all the time.  The dealer has looked at it 4 times
and said that a majority of the 4 cyl. 4x4's do knock, so he advanced the
timing to 0 degrees tds. and sent me home.  I've tried every kind of
gas,every type of fuel system treatment, a Jacobs ultracoil, different plugs,
different wires, different driving patterns, and it still knocks.  The
dealership "said" they checked the egr.
valve and the tps., and reported that they were fine.  Should I just change
these items out and see if the knocking stops, or is there somthing that I'm
overlooking?
I forgot to mention that I bought the truck used from a dealer who said a
junk yard dealer had just traded it in for the larger T100.

I don't know if you can help, but any advice or assistance would be
appretiated!!

Thanks again!
Alan Thornton
athorn5556@aol.com
(919)462-6375

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Date: Thu, 17 Apr 1997 22:58:24 -0700
From: James Brink
Subject: Fwd: 1994 4wd extra cab 4cyl.
To: Toy4x4@tlca.org

AThorn5556@aol.com wrote:
>
> In a message dated 4/9/97 2:12:28 PM, AThorn5556 wrote:
> dear tlca,
>
> < timing to 0 degrees tds. and sent me home.  I've tried every kind of
> gas,every type of fuel system treatment, a Jacobs ultracoil, different plugs,
> different wires, different driving patterns, and it still knocks.  The
> dealership "said" they checked the egr.
> valve and the tps., and reported that they were fine.  Should I just change
> these items out and see if the knocking stops, or is there somthing that I'm
> overlooking?
> I forgot to mention that I bought the truck used from a dealer who said a
> junk yard dealer had just traded it in for the larger T100.
>
> I don't know if you can help, but any advice or assistance would be
> appretiated!!
>
> Thanks again!
> Alan Thornton
> athorn5556@aol.com
> (919)462-6375
> >>
>
> ---------------------
> Forwarded message:
> Subj:    1994 4wd extra cab 4cyl.
> Date:    97-04-09 15:12:28 EDT
> From:    AThorn5556
> To:      toyx4@winternet.com
>
> Dear Minnesota,
>
> I was wondering if any of your members  have any experence with a 4 cylinder
> engine that spark knocks all the time.  The dealer has looked at it 4 times
> and said that a majority of the 4 cyl. 4x4's do knock, so he advanced the
> timing to 0 degrees tds. and sent me home.  I've tried every kind of
> gas,every type of fuel system treatment, a Jacobs ultracoil, different plugs,
> different wires, different driving patterns, and it still knocks.  The
> dealership "said" they checked the egr.
> valve and the tps., and reported that they were fine.  Should I just change
> these items out and see if the knocking stops, or is there somthing that I'm
> overlooking?
> I forgot to mention that I bought the truck used from a dealer who said a
> junk yard dealer had just traded it in for the larger T100.
>
> I don't know if you can help, but any advice or assistance would be
> appretiated!!
>
> Thanks again!
> Alan Thornton
> athorn5556@aol.com
> (919)462-6375

The part about "knocking all-the time" sounds like B.S. to me.
Occasionally, some knocking is normal (like during light accels. or
light-load cruise). Has the dealer tested the truck on a four-gas
analyzer or dyno? It could be that the motor is running too lean (no
codes, right?). Another possibility is the Mass Airflow Sensor is out of
adjustment or has been fiddled with. I don't know of any TSBs on this
topic but I THINK I may have heard of a replacement ECM for the
above-mentioned symptoms. I'll try to look into it.

I would also suggest you try another dealer willing to do a little more
diagnostic work. Is the truck still under warranty? How many miles on
the odo? The dealer may charge you (about $60.00) to run the diagnostic
tests but if something comes up and is covered, you'll be refunded. If
under 50k miles, I doubt there is a problem with the EGR system. It
usually takes around 80K miles or so for them to get carboned-up to the
point of total blockage.

- --
Jim Brink                               1986 Standard Bed 4X4/22R
Toyota/ASE Certified Technician         135,000 Miles
brinkjm@earthlink.net                   32" BFG All-Terrain T/As
                                        Stock 4.10 gears
                                        Rear Lock-Right (TRD)

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