You could try plugging up an o2 sensor and not putting it in the exhaust. (Leave one in the pipe) This should make the ECM richen it up as much as possible if it is actually reading the O2 sensor.
the TSB on this was written 19 years ago - you are crossfiring #7 to #8, route the #8 wire out of the loom and along the intake. (lots dont realize that the 1-5-4 windsor is basically the same firing order as the SBC. crossfire is a biotch and will hammer the heck out of the rod bearings)
then, since some porcelin was gone, compression test #8 - mighta knicked a seat or slightly bent a valve on the way out - that will cause the backfiring (there are really only 2 causes for a backfire: a very hot hole lights off the incoming mix, or the intake valve aint seating)
Quaddriver, thanks for diving this one home so forcefully!!!!
I had read of this issue and even thought that I had satisfactorily checked for it. Brand new Motorsport wires, ran in the dark and looked for any spark getting out - notta.
But, I have always felt it was something spark related (if you go back to my original post you will see my comment about being drawn back to ignition).
Now, after reading your post this morning I figured what the hell I have nothing to loose and my patience is running thin with the one. Came home at lunch and hoped up there and rerouted the #8. Bingo - the ping is completely gone!!!
Now, what I really want to know is how did this truck get to 120,xxxx miles with the original wire routing in place if this is such an issue on these trucks?
Also, why is it only the 7/8 that will crossfire and not the others that have plug wires sitting on each other?
Power is much better now, night and day. I think the computer was obviously retarding the timing due to the knock.
The only issue I have now is that I still have the stumble just off of idle. Not sure how to go about addressing this. I have played around with the idle screw setting trying to change the base throttle angle/tps reading but it seems to run best set as per factory manual.
Any other ideas how to address this? Or is a Ca emissions calibrated ecm just too lean on light throttle?
Quaddriver, thanks for diving this one home so forcefully!!!!
I had read of this issue and even thought that I had satisfactorily checked for it. Brand new Motorsport wires, ran in the dark and looked for any spark getting out - notta.
But, I have always felt it was something spark related (if you go back to my original post you will see my comment about being drawn back to ignition).
Now, after reading your post this morning I figured what the hell I have nothing to loose and my patience is running thin with the one. Came home at lunch and hoped up there and rerouted the #8. Bingo - the ping is completely gone!!!
Now, what I really want to know is how did this truck get to 120,xxxx miles with the original wire routing in place if this is such an issue on these trucks?
Also, why is it only the 7/8 that will crossfire and not the others that have plug wires sitting on each other?
Power is much better now, night and day. I think the computer was obviously retarding the timing due to the knock.
The only issue I have now is that I still have the stumble just off of idle. Not sure how to go about addressing this. I have played around with the idle screw setting trying to change the base throttle angle/tps reading but it seems to run best set as per factory manual.
Any other ideas how to address this? Or is a Ca emissions calibrated ecm just too lean on light throttle?
Thanks for all the input guys!!
sorry I didnt see this earlier....
it might be the case that the wires are inductively coupling all over the place (which is the tricky technical electrical engineering term for it) but the problem we face is that on these wires, the inductively fired plug is 90*BTDC with a fresh fuel charge on a hot engine. the other situations may be a fired plug on an exhausting or BDC or already fired hole.
(sidebar: know what DIS is? aka wasted spark? cylinders 360* out of phase are paired on a coil pack and a spark is "wasted" on a cylinder that just exhausted everything and is about to draw in a fresh charge)
Ok, as of the moment I have all of the plug wires looped, zip ties, separated and going all different ways so they are nowhere near each other. Looks like a tweaker has been in my engine compartment - lol.
The major ping is gone but I am still having the hesitation / stutter just off of idle.
Especially if it is in OD at a very light throttle I get a "shudder".
One other thing I notice is that cruising at low speeds like through a neighborhood, with the throttle just cracked - it will occasionally feel as though it just cuts out or was loosing tps signal or something. Give it a bit more throttle and it clears up.
I have drivin it with the Break out Box installed and did not note any drop in tps signal.
Any other ideas on this one guys?
On another note - What is the difference between a Ca emissions computer and a Federal?
By ing module you mean TFI module?
I put a whole new distributor in it before with no noticeable change in running. Just wanted to freshen everything up.
Also, went to Taylor ThunderVolt 50 wires with the #8 still routed away from 7 just for good measure. Ping is still gone and running good overall.
Just that light stumble right above idle under load. Also, I did install a Federal ECM and it did lessen the stumble. Thinking a custom program with just lightly more fuel at that throttle angle would do the trick. But where and how much $?
Anyone played with throttle body spacers on these engines?
Have you checked your valve seals and make sure they are not seaping oil? Just a thought. My dad showed me a spark plug like that out of his 78 that looked like that. But i dont think it ever miss fired but hope you find you problem man.
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