KA24E Runs Really, Really Rich

[PROJECT240SX]

Hi guys,

Picked up a 1989 SOHC Coupe a few weeks ago and the car has been running really rich. It will shoot out soot upon starting the car and have a strong smell of gas. The car sat around for over a year or so before I picked it up.

I seached around on here and found out that it could be the Engine Coolant Temperature Sensor or the Engine Coolant Temperature Sender. I originally replaced the Engine Coolant Temp Sensor first and it ran the same exact way, I then changed the Sender and ran a little smoother.

I had it on a smog machine and it only seems to be doing it at idle from what the mechanic told me. It will buck at low rpm's and run very sluggish.

Any help is greatly appreciated

[idlafie]

Check your fuel pressure regulator. If its not getting vacuum or is defective, it will allow too much fuel into your combustion chamber causing you to run rich. Make sure you are getting 34 psi at idle & 42 psi under load. A 240SX Nissan Factory Service Manual gives you instructions on how to test it. Use the SEARCH feature here on Zilvia.Net to find a free downloadable version here.

If your fuel pressure regulator is working okay, then use the same Factory Service Manual to check & adjust your Idle & Timing. You're idle may be set too high causing you to run rich. Also check the wire that runs to the Engine Coolant Temperature Sensor. A short in the wire can cause false reading to go to your Engine Control Unit, (ECU), leading the ECU to think your engine is still cold & causing more fuel to be dumped into the combustion chamber.

Also check your Oxygen sensor...use the Factory Service Manual to put your ECU into Diagnostic mode. Once the ECU is in Diagnostic Mode, then test the Oxygen sensor by following the testing procedures in the Factory Service Manual. Chances are your oxygen sensor may fail becuase of all the fuel that's being dumped into the exhaust. You'll probably have to replace it, however make sure you fix the "running rich" condition PRIOR to replacing the oxygen sensor. If you don't, then you'll only be wasting your money as the "running rich" condition will only ruin your new oxygen sensor.

All these checks and suggested repairs should correct your "running rich" problem and have your KA motor purrin' back to it's recommended 750 rpm, clean & smooth running idle.

Anyhow, hope this helps...

ID