1990 240SX fluctuating idle problem - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

jerryk · 02-01-2008, 02:17 PM

I own two 1990 240sx. Both are on the road. I have a fluctuating idle problem with one of them with 177K on the engine. It is scheduled to be my final car. I know what the idle is supposed to be a bit above 730 because my other one with 220K has a perfect idle. The fluctuating /hunting idle goes between 780 and 950 when warmed up or at a stop. Sometime it fluctuates worse then others but it never goes below780 and is always moving. I just made a trip to PA and the road mileage is, I swear 31MPG, but in the city, it ranges between 21 and 23, which is costly these days. The other car gets 25MPG in the city and 30MPG on highway. I have both cars at a mechanic and he has been swapping parts.

Air regulator
AICV
MAF meter
EGR valve

I would appreciate any ideas.

Captain_Ron80 · 02-01-2008, 02:22 PM

Search... there is a thread on this site that explains the problem and the fix.

cotbu · 02-02-2008, 03:21 AM

check your ecu for codes!
I'm thinking CTS.

fairladysx_s13 · 02-02-2008, 02:59 PM

Theres also an idle regulator under the throttle body on the right side. Theres a bolt that moves forward and back that u can tighten and loosen. Try to play with that and see if ur idle levels out.

Vernal · 02-02-2008, 03:16 PM

i had that on my de. The timing was off though. If its a smooth idle but just high then adjust it. If it hunts and bobs then its your timing or a vacuum leak or both.

SilviaSR20DET · 02-02-2008, 04:23 PM

ive actually had this problem for quite some time now, mine usually does this when im using a defroster. I wonder myself what might be the problem behind this. Ill have to check my timing since i havent done so in like 3 or 4 years ago.

02-01-2008, 02:17 PM	#1
jerryk Leaky Injector Join Date: Sep 2006 Location: Island Park NY Age: 84 Posts: 93 Trader Rating: (0) Feedback Score: 0 reviews	1990 240SX fluctuating idle problem I own two 1990 240sx. Both are on the road. I have a fluctuating idle problem with one of them with 177K on the engine. It is scheduled to be my final car. I know what the idle is supposed to be a bit above 730 because my other one with 220K has a perfect idle. The fluctuating /hunting idle goes between 780 and 950 when warmed up or at a stop. Sometime it fluctuates worse then others but it never goes below780 and is always moving. I just made a trip to PA and the road mileage is, I swear 31MPG, but in the city, it ranges between 21 and 23, which is costly these days. The other car gets 25MPG in the city and 30MPG on highway. I have both cars at a mechanic and he has been swapping parts. Air regulator AICV MAF meter EGR valve I would appreciate any ideas. Last edited by jerryk; 02-02-2008 at 03:56 AM..

02-02-2008, 03:21 AM	#3
cotbu Post Whore! Join Date: Sep 2005 Location: SWFL Age: 50 Posts: 3,318 Trader Rating: (3) Feedback Score: 3 reviews	check your ecu for codes! I'm thinking CTS. __________________ LoverTechnologies "Half Broken Things!"

02-02-2008, 02:59 PM	#4
fairladysx_s13 Leaky Injector Join Date: Oct 2007 Location: chicago Age: 35 Posts: 74 Trader Rating: (0) Feedback Score: 0 reviews	Theres also an idle regulator under the throttle body on the right side. Theres a bolt that moves forward and back that u can tighten and loosen. Try to play with that and see if ur idle levels out. __________________ New_Era Jay

02-01-2008, 02:22 PM	#2
Captain_Ron80 Leaky Injector Join Date: Sep 2007 Location: Portland Age: 45 Posts: 122 Trader Rating: (0) Feedback Score: 0 reviews	Search... there is a thread on this site that explains the problem and the fix.

02-02-2008, 03:16 PM	#5
Vernal Zilvia Junkie Join Date: Aug 2006 Location: Burbank, CA Posts: 517 Trader Rating: (0) Feedback Score: 0 reviews	i had that on my de. The timing was off though. If its a smooth idle but just high then adjust it. If it hunts and bobs then its your timing or a vacuum leak or both.

02-02-2008, 04:23 PM	#6
SilviaSR20DET Zilvia FREAK! Join Date: Mar 2002 Location: Seattle, WA Posts: 1,221 Trader Rating: (9) Feedback Score: 9 reviews	ive actually had this problem for quite some time now, mine usually does this when im using a defroster. I wonder myself what might be the problem behind this. Ill have to check my timing since i havent done so in like 3 or 4 years ago.