Questions and Answers

Nissan 200-SX Breaking Up Q. Vincent, I recently acquired a 1986 Nissan 200-SX. I am fairly competent at fixing most anything on most vehicles. When the car revs over 3,900 rpm it seems to miss fire badly, the tach bounces like a hamster on speed and it may or may not quite running. I’ve looked at many web sites and reading your responses to others regarding the ignition module led me to believe that this may be the problem.

As far as I can tell, it doesn’t have any of the characteristics of the problem though. I have done all the obvious fixes, plugs, distributor cap, new gas, etc. I am now at a loss for ideas. I don’t want to spend $240.00+ for the ignition module if I don’t have to.

Any suggestions would be appreciated.
Scott

A. Before I go and replace the ignition module, I would test the Throttle Position Sensor. They do go bad and create similar symptoms.

Unplug the TPS and check for continuity between the center pin and the idle contact pin. There should be continuity. Slowly increase engine speed to 900 rpm. At 900 rpm the contacts should show open. They should remain open all the way to full throttle. If not, then the TPS is bad.

Now go from the center pin to the full throttle contact pin. There should only be continuity when the engine is at full throttle. Open any other time.

Now go from the center pin to ground and move the throttle. It should read open the whole range of all three contacts. If there is continuity at any point, the TPS is shorted and needs to be replaced.

If the TPS checks out okay, then you are most likely looking at a bad ignition module.