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Discussion Starter · #1 ·
it's a 1994 lt1 with 98xxx miles running long tubes and no cats. It's running like crap, backfiring, and stumbling. when i pop the hood at night the plugs are all arcing from the boot to the head and the coil wire arcs as well. it's like it's just trying to find a way to ground, but i've checked all the connections and replaced plugs/wires twice. the exhaust smells like gas *running rich*. i've checked the fuel pressure and it's reading okay. i've scanned it and it's not giving me any codes; the O2's read fine, as does everything else. So far i've replaced the plugs *ac delco platinums*, wires, opti *sensor, not cap and rotor*, coil, and i've had the ignition module checked. It's even worse when it's hot out side, regardless of whether or not the engine is. i am completely clueless, and i would really appreciate any help at all.

*if i've forgot to cover something, just ask*

Super Moderator
7,058 Posts
your cats are working HARD scrubbing the exhaust enough to keep from throwing a code.
Fooser reread his post, there are NO CATS, they have been removed.

I don't belive that this is a grounding problem, the reason is that the spark is jumping to the block from the wire and the starter motor would use the same ground back to the battery so it would turn very sluggish when attempting to start this motor, is that happening? If it is then do check all grounds.

Three things I would look at:
1) spark plug gap, did you set the gap properly? If the gap is to big (some try it to get a longer hotter spark) then the spark will try to jump from the wire to the block.

2) Did you use the SAME part number for the AC Delco's plugs? Even a different number but same type design will have different resistance which will throw the whole ignition system out of wack. Too much resistance in the plug and the spark will look for a different way out.

3) You tested the system pressure, did you test the "holding" pressure? When the key is off the system should hold fuel pressure for a specified time, if not then is it a leaking fuel injector, fuel regulator, or even a leaking valve in the fuel pump releasing the pressure?

Hope this helps, Kenny.
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