I have a 1997 nissan pickup with a 2.4l 4cyl engine and it idles rough. On idle it sounds like a V8 with a big cam in it, you know kind of lopey. When i drive it though it seems fine. The engine runs smooth if i'm on the road driving, but sitting it idles up and down from about 900rpm to 600rpm. Any solutions???

Here are the 3 engines listed for this year. IGNITION TIMING

2002 Nissan/Datsun Truck Frontier Pickup 2WD 2.4L SFI 4cyl

The Ignition Timing

18-22 DegreesBefore top dead center - When throttle positionsensor disconnected and using suitably programmedscan tool.When adjusting idle speed, set parking brake & chock drive wheels, curb idle speed (750-850 RPM)transmission in neutral.

IGNITION TIMING

2002 Nissan/Datsun Truck Frontier Pickup 2WD 3.3L SFI 6cyl

The Ignition Timing

8-12 DegreesBefore top dead center - throttle position sensorharness disconnected.When adjusting idle speed, set parking brake & chock drive wheels, curb idle speed (700-800 RPM)transmission in neutral.

IGNITION TIMING

2002 Nissan/Datsun Truck Frontier Pickup 2WD 3.3L SFI SC 6cyl

The Ignition Timing

8-12 DegreesBefore top dead center - throttle position sensorharness disconnected.When adjusting idle speed, set parking brake & chockdrive wheels, curb idle speed (700-800 RPM)transmission in neutral.

I'm sure your check engine light is on try....
https://www.autozone.com/landing/page.jsp?name=top-five-reasons-check-engine-light

For this types of problem,there are few help inks to troubleshoot the problem.Click the link below to go through the troubleshooting procedure to resolve the issues :----Idles rough and quits when gas pedal is pressed less? http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html-----------van idles rough? http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html
--------------runs lean and idles rough? http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html
-----------Car still runs Rough after tune up? http://howtobyme.blogspot.com/2011/12/car-still-runs-rough-after-tune-up.html
------------Idle flair is noticed on car? Rough idle? car will not idle? Erratic idle speed? http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html
----------High rpm in neutral? Inconsistant high RPM in neutral? http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html
------------Engine Backfires? http://technoanswers.blogspot.in/2012/02/jeep-backfires.html----------- Nissan stalls and bucks on Acceleration?

http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-stalls-and-bucks-on.html

-----------
Nissan Pathfinder Backfires? http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-backfires.html
---------How to adjust rpm? http://schematicsdiagram.blogspot.com/2011/12/how-to-adjust-rpm-on-2009-dodge-charger.html
------------Engine cuts out at 3000 RPM? http://schematicsdiagram.blogspot.com/2011/12/engine-cuts-out-at-3000-rpm.html
----------This will help.Thanks.

im having the same problem w my 97 bird... lopey or rough idle. no luck yet changed or tested many sensors already... if you have any tips let me know and ill do the same, [email protected] Thanks

try a tps throttle posistion sensor the engine is not idling fast enough with the ac on thats why it stalls if you have a manual adjustment on the throttle body speed the engine up 150-200 more rpm this should solve the problem.

Visit the on-line store, know as reliable-store, they have the repair manuals. I'm sure you will get the solution of your problem.
Nissan Maxima Factory Service Repair Manual 1994 2009

follow the given link,it may be useful for you 1997 Nissan Pickup Service Repair Manual

the idler valve this controls the air into the system, looks like this.
remove and clean out using carb cleaner or solvent based cleaner that won't damage ruber.

ok i have the same truck my timing was off 3 teeth but mine wouldn't kick out of high idle is y mine was surging but know with timing right no vacuum leaks i cant get it below 1400 but when a vacuum turns on it almost kills my engine any thoughts i know i got a vacuum line mixed up idk were though