Engine Performance problem
1990 Other Nissan Models 4 cyl Two Wheel Drive Automatic 51000 miles
Do not not drive this car a lot. Recently I noticed the speedometer working erratically. Then it would work and not work. I did not give it much attention. Until the car would not go over about 2500 rmp and gas millage became really bad. I looked into the repair manual and alldata infomation plus Atuo Zone site and determine the car is in limp mode.
I changed the speed sensor and the computer but the these did not help. I tested the battery - the result is good - 12.5V. All fuses are good.
Also, I noticed when I unplug the o2 sensor the check engine light(CEL) would not come on. The same for other sensors I unplug. The CEL would not come on.
When I remove the speed sensor I see the gear in/on the tranmission. It does not look like it is broken off. I tested both speed sensor (old & new) and they give out average.4 v. Right now the speedometer works sometimes.