3.9l v6 oddities (pinging etc) kinda long, but I'm desperate!

From: Wes Weems (wweems@fix.net)
Date: Fri Nov 02 2001 - 00:10:14 EST


Ok,

I've had my 97 Dakota sport for a little over a year... and I am kinda
curious as to if anyone else has experienced similar problems...

My truck has what appears to be a slight pinging problem... (kinda sounds
like a tinny rattling noise, usually around 3000-3500 rpms)... and usually
doesnt do it if I am going hard acceleration... just gradual or driving at a
constant 3000 or so rpms.

I've checked and I dont have a belly pan gasket problem... I'm running 89
(but have gone as high as 100 octane -- octane booster etc) I've had the
spark plug re-route, and taken it to the dealer several times. I am almost
thinking now that this noise may not be a pinging dakota at all.

I've noticed the sound of my exhaust doesnt sound nearly as deep or none of
the resonance it used to have, and I suspect for whatever reason it might be
running lean. I think the following may be culprits, but would like better
advice:

1) possibly need new injectors as I am about 71000mi into the current set
2)possibly need a new cat (though the cat is fairly recently installed, and
the rattling doesnt ppear to be coming from there.
3)o2 sensors (I've replaced the front one, and had it fix the sound of my
truck temporarily) was told replacign rear o2 sensor wasnt necessary
4)other sensors (the sensor that sits right on the front of the tb was
replaced, IAT cleaned, front o2 sensor like I said)

I am kinda at the end of my whits here... I'd like to start building this
engine to be a little quicker, but in my experience if I was to even so much
as toss a FIPK intake on it, it cause it to ping like mad. My computer has
been flashed once... and didnt really improve anything to my knowlege.

Please help!
Wes



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