97 Hardbody KA24E Distributor Problem?

[88m5]

I am trying to see if I am on the right track. My 97 Nissan drop from 25 MPG to 20mpg. I did a complete tune-up using factory nissan parts, cap wires,rotor and plugs. Along with filters. I notice my truck seems to run just sluggish. I check the codes and ther are no codes. It felt like the distributor is not advancing when I give it gas. So I bought one of those scan gauge II. Sure enough the timing is moving from 10 degrees to 12degree some time to 15 degrees. It never goes up to 25 or higher when you give it gas. I took the scan guageII and plug in to my toyota and my pontiac just to see what they do. Both of them when you are taking of goes to 31 degress then gradually comes down. My nissan will sometime go all the way down to 6 degrees. So what actually tells the distributor what to do other than the ECU? The ECU must get inputs from the Intake Air Sensor and other sensors. My truck has 127,000 miles is 2wd and automatic. Any ideas.

Thanks88M5

97NissanPU

[Rev_D21]

Are your vacuum hoses in decent shape?

[88m5]

yes I check the vacuam hose.

[nismopu]

The nissan ecu rely's alot on the AFM, and crank angle sensor which is inside your dizzy itself. Like suggested above vacuum lines can cause problems but it would most likely be a very noticable vacuum leak to affect the readings your AFM will see. Try cleaning the AFM with some AFM(air flow meter) specific cleaner. If you don't know already its under the air filter box inside the throttle body. Do you know anybody with a 98-2000 frontier or another 97 to try another dizzy with? If its your CAS thats bad it will require a whole brand new dizzy. peace.

[88m5]

are you refering to the cam position sensor in the distributor? Is that what you are calling a dizzy?

[88m5]

I did clean the AFM sensor.

[nismopu]

97's sometimes have both a cam sensor and a crank sensor. The one inside the distributor(dizzy) is in fact the cam sensor, yes. peace.