Problem engine rough @ idle and moderate speed.

[jerryk]

I just picked up a second red 90-240SX hatch(new). I plan to use this car as the body and my (old) red 240SX as the parts car. Everything in my old 240SX is running perfectly the engine has 210K and I have owned and taken car of it all these years. The problem with the old car is the underbody is almost completely gone and that is the reason for the (new) car. The plan is to take the best parts from each and create one car. Both cars are stock and have the same colors. The only difference between the two is the (new) car has ABS, which I plan to dump.

Problem:
The (new) car engine with 175k, which I was thinking of keeping, is very rough at idle it is also rough when you accelerate moderately. I had a compression test and the results are posted below. I checked out the plugs and they were clean. I changed the oil, plan to change the rotor wires and plugs but I do not think this will help. I am not sure that the problems are related. What should I look for next? Someone on another forum said the throttle body had to be opened and that the numbers were low.

Nissan 1990 240SX Wet and Dry Compression test

CYL1----CYL2---CYL3-----CYL4
155------156----155------158_____DRY
12.90%--8.97%--13.55%--13.92%
175------170----176------180_____WET

Remember my (old) car can be used for parts
http://www.smugmug.com/photos/136240163-L.jpg

[s13rookie]

The comp numbers on the newer motor dont look too bad. If you have another car thats running fine, why dont you swap the dizzy. spark plug wires/ etc and see if that fixes the issue. I didnt see if you said you changed the fuel filter but it never hurts and its only a few dollars.

Check the timing also when you do the dizzy swap

good luck