Tachometer abnormality

[popogto]

89 240sx w/ 95 KA24DE

I just installed a Sunpro super tach. for the line reading the RPM signal, i spliced it into the wite wire comming off of the distributor.when i start the car, the tach runs fine. when i rev the engine, the tach is normal up to around 3400 rpm, any more, and it will drop to about 1800 and rise again.the Engine RPM is steadily climbing, but the tach is wrong. any help is much appreciated.

[eliterit]

did u set the sunpro tach to 4cylinders, i know it has settings for that and 6cylinders and v8.

if you already did that i have no clue. i've used a 2nd hand sunpro tach and it sucked. sometimes it acted fine, sometimes not. i threw it away.

[popogto]

i e-mailed the tech support, they said to splice into the red/yellow wire comming off of PIN3 on the ECU. gonna try that as soon as i figure out where / how