1991 240sx: idle drops 100 rpm when heater turned on - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

surreybc · 06-05-2008, 06:57 PM

this is the interior heater. Turning on the heater obviously lowers the temperature of the engine coolant so i assume there are less demands on systems so ecu lowers the idle?

RedtopTech · 06-05-2008, 09:42 PM

it's actually the electrical load of the blower motor that drops the rpm. Turning on the headlamps at idle will produce the same effect. It's not really an issue, most late model and many newer cars do this. Just make sure you have a good charging system.

nixad · 06-05-2008, 09:46 PM

postlenght

surreybc · 06-05-2008, 09:57 PM

Quote:

Originally Posted by RedtopTech

it's actually the electrical load of the blower motor that drops the rpm. Turning on the headlamps at idle will produce the same effect. It's not really an issue, most late model and many newer cars do this. Just make sure you have a good charging system.

ok. i'll have to check the amps for the blower. I never thought of it as placing much demand on electrical system. Also, I thought that the idle is supposed to go up to compensate for increased electrical loads. My lights lower the rpm about 50 rpm.

Im trying to figure out why my idle plummets to around 500 on cold days when I push clutch in. It plummets quite a bit less when the heater fan motor is off. Ill have to try a new iacv.

bbejj123 · 06-05-2008, 10:34 PM

when u push your clutch i believe there are fans for the clutch to help it cool and not overheat which activate when the clutch is engagded but since it is cold already im not sure exactly how its setup

Z U L8R · 06-05-2008, 11:51 PM

heh ^

surrey, more info plz. what is the idle normally? what if you push in the clutch only? what if you turn on your blower only?

what motor, and what car?

Dave

xsparc · 06-06-2008, 12:20 AM

it all depends on the condition of you charging system and alt. mine drops by 100 too when my FAL fans come on.

white92_s13 · 06-06-2008, 12:37 AM

when i turn the heat on, i drop about 100 rpm as well. turn ac on and it kicks up from 800 or so idle to 1100 or so with the ice cold ac blowing

surreybc · 06-06-2008, 12:50 AM

Quote:

Originally Posted by Z U L8R

heh ^

surrey, more info plz. what is the idle normally? what if you push in the clutch only? what if you turn on your blower only?

what motor, and what car?

Dave

KA24DE standard 1991 240sx hatch

If I'm just idling with car at standstill, depressing clutch does nothing to idle but turning on blower drops idle the same 100 rpm. Normal idle is around 800 rpm.

The idle just plummets on cloudy days but on sunny days I dont have that problem.

06-05-2008, 06:57 PM	#1
surreybc Zilvia Junkie Join Date: Mar 2008 Location: surrey Posts: 359 Trader Rating: (1) Feedback Score: 1 reviews	1991 240sx: idle drops 100 rpm when heater turned on this is the interior heater. Turning on the heater obviously lowers the temperature of the engine coolant so i assume there are less demands on systems so ecu lowers the idle?

06-05-2008, 10:34 PM	#5
bbejj123 Zilvia Junkie Join Date: Nov 2007 Location: La Crescenta Age: 35 Posts: 482 Trader Rating: (0) Feedback Score: 0 reviews	when u push your clutch i believe there are fans for the clutch to help it cool and not overheat which activate when the clutch is engagded but since it is cold already im not sure exactly how its setup __________________

06-05-2008, 11:51 PM	#6
Z U L8R Zilvia FREAK! Join Date: Jan 2007 Location: Georgia Age: 43 Posts: 1,194 Trader Rating: (0) Feedback Score: 0 reviews	heh ^ surrey, more info plz. what is the idle normally? what if you push in the clutch only? what if you turn on your blower only? what motor, and what car? Dave __________________ RB25 280z GT30/76R 441hp/381tq 11.9@125

06-06-2008, 12:20 AM	#7
xsparc Zilvia Junkie Join Date: Dec 2002 Location: san diego area - esco Posts: 461 Trader Rating: (0) Feedback Score: 0 reviews	it all depends on the condition of you charging system and alt. mine drops by 100 too when my FAL fans come on. __________________ No... no one stole my interior... its safely in my garage...

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06-05-2008, 09:42 PM	#2
RedtopTech Zilvia Member Join Date: Dec 2005 Location: Virginia Beach, VA Age: 40 Posts: 293 Trader Rating: (0) Feedback Score: 0 reviews	it's actually the electrical load of the blower motor that drops the rpm. Turning on the headlamps at idle will produce the same effect. It's not really an issue, most late model and many newer cars do this. Just make sure you have a good charging system.

06-05-2008, 09:46 PM	#3
nixad Zilvia Member Join Date: May 2006 Location: Long Island, NY Posts: 163 Trader Rating: (0) Feedback Score: 0 reviews	postlenght

06-06-2008, 12:37 AM	#8
white92_s13 Leaky Injector Join Date: Mar 2008 Location: goodyear az Age: 36 Posts: 94 Trader Rating: (0) Feedback Score: 0 reviews	when i turn the heat on, i drop about 100 rpm as well. turn ac on and it kicks up from 800 or so idle to 1100 or so with the ice cold ac blowing