93 Explorer Vacuum Modulator?
 

I purchased a 93 Explorer not long ago and it was running great but just about 3 weeks ago it began to have issues it had a massive leak and it would have trouble accelerating. I took it to a transmission shop and I was told that it was the vacuum modulator. So I decided not to do anything and just put in the garage until I can afford that. But I need that SUV in running condition soon, so I have a couple questions. They said that it would cost about $300 to replace. Is that really the cost to replace that part? How much is a vacuum modulator? What exactly does the modulator do?

I would be so thankful if anyone could help me.

The vacuum leak is because the vacuum modulator diaphram ruptured and allowed trans fluid to be sucked up into the intake. This contaminated the rubber fittings at the drivers side rear of the intake and they swelled up and then fell off. Not an unusual thing to happen on this older vehicle. The vacuum modulator is not hard to replace, just have to remove the catalytic convertor on the passenger side and then you can get right to the modulator. Be careful pulling the modulator out, as there is a shift pin behind it and it must be reinstalled with the new modulator or it will not shift properly. The modulator will run you about 60.00 at the local dealer. You will also need a gasket for the catalytic convertor.