Dollar bill test....

[grandprix34]

i failed...

I put a dollar bill in front of the exhaust pipe and it suxs it in some...what could this be? Its not constant, but intermediately....please help

[Rhedalert]

I don't get it....I'm interested in hearing it though

[grandprix34]

well, honestly, im not sure what the test proves....i did it because my engine seems to misfiring, though not to the point where the car struggles to run. At stop lights or while idling, the RPMs seem to drop to almost stalling.

I have a vacuum gauge and it reads a little into "LATE IGNITION TIMING" section. I can get the vacuum ready if anyone things it would help

[SappySE107]

Im not sure how well that works on a fake dual muffler setup. Ive never even heard of this test though so I dunno.

[grandprix34]

well i checked the plug wiring and turns out cylinder #6 is not firing...i pulled the boot and attached an external spark plug. No spark while cranking...tried it again wit the plug wire away frmo the blcok....one spark while cranking. I turned the engine over and the car ran like it did WITH the spark plug wire connected. So i am narrowing down to the ign. wire and not the coil since i strongly believe that only this wire is not firing.

p.s.-when relocating the coils so the exhaust manifolds wont destroy my 2nd set of cheap wires ( ), does the 5wire, 3wire, and 2wire harness extend or will i have to splice some wires (ie. cutting, making any harness wires longer).

[SappySE107]

You will probably have to solder new wire in to extend them to the new location.

[RacerX11]

You actually have 2 cylinders not firing. On the DIS system, if one plug on a coil isn't firing, the other one can't fire either. Might want to check again on a bad coil. You can try switching coils and see if the problem follows the coil.

Marty

[SappySE107]

If its a bad wire, why won't the other cylinder still fire? You can pull 1 plug wire off and the other one still fires so I don't know what the difference is.

[RacerX11]

It shouldn't fire. The way the watse spark system works, the spark path goes from the engine, through the first plug, through the coil, through the second plug, back to the engine. If you pull the wire off one plug, there is no current path to complete the circuit to allow the companion plug to fire. There is no absolute ground reference for the secondary windings on the coil, other than through the two plugs. On every DIS car I have worked with, the cylinders stop firing in pairs.

Marty

[SappySE107]

Hmm, i thought it just grounded through the spark plug. Ive seen a 3.4 DOHC idle close to ok, slight miss with the 1 wire pulled out. If it were just 4 cylinders going I would have suspected it to be much rougher. Ive heard about it going through the block as well to complete the path.

[Juglenaut]

It will believe me....It will on a bad wire....

Move the suspected bad wire to the other tower on that coil (swap wires) and retry

[Juglenaut]

It shouldn't fire. The way the watse spark system works, the spark path goes from the engine, through the first plug, through the coil, through the second plug, back to the engine

Sure waste spark works that way, but the spark that returns back to the coil not thru the coil the primary triggers twice per revolution. Waste spark means the spark is absorbed in a closed system (you don't get shocked when touching the plug wires or the engine when connections are made).

Spark hummm travels super fast >>>>>>>>>>so the way you explain it the spark would advance the next cylinder by a huge amount.

If you pull the plug....get this the spark will look for the nearest ground!!!!!Even jump the plug at the coil wow who woulda thought.

Even if the spark goes to earth ground it is terminated, mpst times it will jump from you or the plug to the metal in the car. I even seen a spark come back out of the earth ground just to get back to the coil.

[grandprix34]

I've had a coil go out before and the car ran like a Honda on crack (complete shit). The engine idles almost ok, the car runs fine, though not as responsive of course...when mashing on the gas pedal, it would usually jump frmo 2 to 4 or 3.5K and pull hard as hell...now it climps just from 2K to 3K or 3K to 4K and midly pulls like its lost its balls.

Im going to replace the spark plug wires with Taylor 8mm wires and see if that helps out. Also planning on relocating the coils cuz i burned my hand 2day again..

[Juglenaut]

If you had a coil bad yes if one side don't fire either does the other, and a no fire like that would make the DOHC sound like a honda that has a bad fartting blubblubbulub problem. I set mine up that way once by accident and I came up on some ricers they thought it was awesome sounding....Had a bad coil from Accel and went totest it, believe me it was louder than if it were just one cylinder no fire situation. I switched to MSD's.

[Cotton]

Re: Dollar bill test....

i failed...

I put a dollar bill in front of the exhaust pipe and it suxs it in some...what could this be? Its not constant, but intermediately....please help

overlap. people used to claim if the exhaust exhibits a 'sucking" action, then the engine has a burned valved, or a valve not sealing properly for for other reasons.
This is not true for todays engines due to some valve overlap being designed into the camshaft. the overlap aids in cylinder filling during intake stroke.
If you have retarded you exhaust cams, the "dollar bill" test will be more pronounced.

about the coils, pull one plug wire off of one coil, remove the other wire on that coil from the sparkplug and install a spark tester to that wire, start the engine and watch both of the coil towers fire.