Transmission Modulator

[iceman2]

I have a 1997 Transport with 135k miles, the other day I was turning a corner when I noticed a skip, fuel light was on so I figured I was running out of gas, later that day I was stopped at a light and when it turned green, I gave it gas, the engine revved but van did not move, slammed it to neutral, then back to drive and away I went, went to Avd Auto the next day and replaced the transmission vacuum modulator, $13. The old mod had fluid coming out from the end that goes into the transmission, so my question: Was this more than likely the problem? I know only time will tell. If this isn't it, what's next?

thanks.

[LMP]

Quite possible though a failed diaphragm would look as full throttle and I would have expected the opposite (that it keeping gears to high rev) ...but maybe I do not figure it out correctly or some internal freak failure mode behaves like that.

[iceman2]

Thanks, LMP, 10 days with the new modulator and no (knock on wood!) problems. The transmission fluid looks a little discolored, not the bright cherry red - kind of dull/dirty slightly greyish red, never changed transmission fluid before, is this difficult?

[LMP]

..great...changing fluid is dirty job because of no drain plug..so you unbolt the transmission pan and it starts flowing all around ....need a large funnel...and then about 1/4 to 1/3 of the fluid still remains in the torque converter. Once transmission pan is down, check condition of filter or/and accumulation of dirt at bottom of pan...in fact, one would not go into that operation without changing the unexpensive filter on the way.....
If there is no significant debris, then you can go without flushing the converter but in doubt, a full flush would be required....I'll look for an"official" method some have posted in this forum.... since you say the fluid is somewhat opaque, the amount of debris might be significant.

http://www.automotiveforums.com/vbul...d.php?t=537445

One can avoid the service station "flush" by doing it twice...that is an option: first remove oil pan, CLEAN filter as much you can using solvent, reinstall and fill up and you have about 3/4 new oil and 1/4 dirty oil. GM book says 6 quarts in pan, 2 quarts left in torque converter, hence 3/4 1/4. RUN the car a few times...which will mix new and old remaining fluid then drain again and then install new filter and refill again with fresh fluid.
THis way you have around 7% contaminated fluid remaining ( 1/4 x 1/4) but with the new filter it is OK. ANd even if you fill up twice, you end up using no more fluid than the service station flush and you save the 1 hour time fee....well since I have time to do that and I have a pit that would be my option.... HOwever since my transmission fluid never got opaque, I was statisfied with the 75% refill...done at the time the transmission cooler lines broke ...

[iceman2]

Well, just a follow-up, trans continues to function properly, what a nice tip from this forum about that modulator, very easy and cheap part to replace.

[xsmilk]

iceman2.. Question... what direction were you turning when you noticed the engine skip??? shudder while turning has come up and I'm wondering if there is a relation to the modulator

The reason i ask is that you say "The old mod had fluid coming out from the end that goes into the transmission, ".. if the modulator monitors engine vacuum and contained fluid which could shift during a turn would this cause the engin to skip??/... if so ... could this be a source of other problems nted on the site re: hesitation while turning??? let me know if I'm way off base the learning curve here is pretty steep