My Car: 1990 Nissan 240SX, Automatic, KA24E.

Body: 190,000 Miles, Motor I'm told has about 90,000 miles and was replaced a few years ago.

Questions:

1) Car seems to have a rough idle and fluctuates between I would say 500 - 800 RPM at idle. I changed the Spark Plugs Today, Wires will be changed tomorrow along with Distributor Cap. Any other recommendations? I know the Air Intake has some Black Tape wrapped around at some parts, could their be a leak? I've also heard of the Air Control Sensor, EGR Valve, Fuel Filter, Etc. So I would like the Pro's to tell me, what do I need to replace to give this car a really good tune-up?

2) When I am in PARK, I rev up to about 1.5-2000 RPM and I hear this rattling coming from somewhere, can't tell if it's the exhaust or the motor. ALSO, when the RPM's begin to drop, it hits around 1k RPM, sometimes I hear this grinding sound, almost the sound of a fan or something scraping something, but sometimes it doesn't do it. Any idea?

Standing by for Answers, will Give Rep!

 

First make sure your idle is set correctly. Pull the tps connector and adjust idle to (I think) 500rpm.

 

Do you have a Diagram anywhere or instructions on how to do this? I greatly appreciate it. I have never worked on my own cars, so I think now is the time.

 

you hear the timing chain hitting the guards, happens to most ka's and wont affect the performance.

 

Okay. What about Rough Idle?

 

set idle. google ftw. you will quickly be able to find a thread explaining how to do this.

 

Well yes and no. It can have a rough idle and be at the right engine speed, too. In that case, check the ignition timing with a timing gun. If that doesn't do it, you're probably running lean at idle/under vacuum. For that, check for leaky vacuum hoses, disconnected hoses, etc.