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Engine Mis-Fire = Better Shifting???

I'll keep this as short and sweet as possible!

I have been dealing with a hard 1-2 upshift for months on end now. I've had the transmission serviced along with a New adjustable Vacuum Modulator installed, but that did not help at all. The transmission is a 440t4.

Recently, I had a spark plug wire rub-up against my exhaust manifold, split open, and cause a cylinder misfire. It happened while driving. The car was still driveable, so I drove it to my mechanics to figure out what was going on.

On the way there, while driving with the misfire, I noticed that my

1-2 upshift had some how cured itself, and the transmission was now shifting perfectly? I actually drove it for a little longer than it would have taken me, just to make sure I wasn't losing my mind, and not once did it make the annoying slip/pull/bang that it normally does when going into 2nd gear.

Some one on another Forum stated that it could possibly be due to a bad Vacuum Modulator. They stated that a misfire causes a loss of vacuum, and that I should try adjusting my modulator by turning the "T" inside it counter clockwise, which will basically lower the vacuum, and do the same thing as the misfire did?

Does this make any sense at all?

Reply to
bigbossfan80
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Hmmmm...nobody? Strange...I normally get at LEAST one reply!:(

Reply to
bigbossfan80

Maybe folks are confused because your have it backwards. When the vacuum is low, the modulator allows pressurized fluid to enter onto the side of the spool valve in the pressure regulator, which allows for an increase in pressure. Your apparent smooth shifting was due more to low power than to low vacuum. Depending upon your modulator you might adjust it, but you need to pull the center part out slightly betore turning the key. It's hard to ESTIMATE vacuum, but you're welcome to experiment. A guage is best. Has your transmission has been modified internally to produce the hard shift?

Reply to
MaxAluminum

Thanks for you reply!:) Yeah that's what has me confused as well. I know that a misfire would cause LESS engine Vacuum, but this contradicts the fact that it made the shifts LESS hard? I know that with regards to modulators, less vacuum equals harder shifts, and more vacuum equals softer shifts, so the fact that less vacuum made my tranny shift softer is incredibly strange!

UNLESS, I'm mis-feeling the 1-2 upshift. In other words, is it possible for an upshift to slip so badly, and be so soft, that it actually causes a "bang"?? If this is the case, than maybe this "bang" I've been feeling is because of a slipping/soft shift, and not a hard shift?

I don't know, maybe I'm analyzing it too much!!!:)

I think I'm gonna try disconnect the vacuum hose from the modulator and see how it shifts than...

Reply to
bigbossfan80

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