Questions and Answers

High Revving Nissan 200SX

Q. I have a question for you. I just got a 1986 Nissan 200SX with 136,000 miles from a friend it drives great, there's only one problem. It shifts very high at about 4200RPM . I'm familiar with GMs and it feels like the kick down cable, however there is no cable on the car and according to the dealership this car never had one. Its a 1986 with the 2.0L engine, and an automatic tranny. Its not that big of a deal but when I drive slow it gets annoying to be in first gear at 25 miles an hour doing 4000RPM. Any info would be greatly appreciated.

Thanks,
Gregg

A. This is an easy one. That transmission has a vacuum modulator to help control the shift points. It has a diaphragm inside of it that will develop a hole and will cause the shifting to become erratic.

You need to get under the car and locate the modulator. I believe it's on the left side on the transmission. there is a short, 90 degree molded vacuum line connected to it. Pull the vacuum line off and see if any transmission fluid comes out of it. If it does, the diaphragm is bad and you will definitely need to replace the modulator.

If no fluid comes out, that doesn't necessarily mean it's good however. At this point trace the tube up to the engine and make sure there are no vacuum leaks and the hoses are in good shape. If they are and you're getting vacuum down to the modulator, then go ahead and replace it.

When you remove the modulator there will be a short steel rod going into the transmission. This serves as an adjustment for the shift points. There are several lengths of rods available for adjustment. You shouldn't need to change it, just make sure you don't lose it and make sure you put it back in. FYI... the longer the rod, the higher the shift point, the shorter the rod, the lower the shift point.