Do YOU know why... cause I sure don't

insane · 05-06-2005, 05:40 PM

I have a 91 240sx(ka24de) that wont idle right, when I first start it up it idles around 1200 rpm, I think this is to help warm it up, then it drops to the 500-700 rpm range but it bounces around, now lets say the engine is warm and I am ready to drive it around, well it runs great while the clutch is engaged so great that I had the speedometer needle past 110 and touching the bottom part of my display at 5000 rpm in 5th gear but the problem is when I put the car in nuetral and hit the brakes to slow down the engine drops to idle then revs itself up to 2000-3000 rpm then drops back to the bouncy idle and when the car is at idle if I were to press and release the throttle in a split second it would still rev up like that and when the A/C is on the car does the rev thing but will stay reved for however long it wants to unless I turn the ac off. the check engine light does not come on and yes the bulb does work, I did the ecu self diagnostic thing and it said "all is cool" The car has given me these problems since the first day I owned it it was a auto when I bought it it is now a 5 speed with the auto ecu still. any help would be great.

tougeC · 05-06-2005, 08:45 PM

lol im far from an expert but i would say get rid of the auto ecu.

insane · 05-06-2005, 11:49 PM

I just found out my timing chain is loose, but would that cause the weird reving? I cant seem to find any info about this in my fsm.

TeamSLIPdrifter · 05-07-2005, 06:24 AM

lol get that ecu out of there...

insane · 05-08-2005, 02:30 PM

do you guys think my ecu is broken or do you think I just need a 5 speed ecu because I now have a 5 speed tranny

unless it is malfunctioning the ecu should not be a problem because the car was giving me these problems when it still had the auto tranny.

TeamFazzne · 05-08-2005, 04:27 PM

i dont think that it has anything to do with the auto ecu. i have a manual and it does the same thing. is there any aftermarket parts on your car?>

DriftspecCowboy · 05-08-2005, 05:40 PM

Check your IAC valve. I had the same problem.

GotNismo? · 05-08-2005, 07:31 PM

the timing would affect the jumps in the a/c but the 750-500 idle bounce, sounds like a vacuum leake somewhere. my rx7 used to do that.

05-06-2005, 05:40 PM	#1
insane ...are you? Join Date: Aug 2004 Posts: 89	Do YOU know why... cause I sure don't I have a 91 240sx(ka24de) that wont idle right, when I first start it up it idles around 1200 rpm, I think this is to help warm it up, then it drops to the 500-700 rpm range but it bounces around, now lets say the engine is warm and I am ready to drive it around, well it runs great while the clutch is engaged so great that I had the speedometer needle past 110 and touching the bottom part of my display at 5000 rpm in 5th gear but the problem is when I put the car in nuetral and hit the brakes to slow down the engine drops to idle then revs itself up to 2000-3000 rpm then drops back to the bouncy idle and when the car is at idle if I were to press and release the throttle in a split second it would still rev up like that and when the A/C is on the car does the rev thing but will stay reved for however long it wants to unless I turn the ac off. the check engine light does not come on and yes the bulb does work, I did the ecu self diagnostic thing and it said "all is cool" The car has given me these problems since the first day I owned it it was a auto when I bought it it is now a 5 speed with the auto ecu still. any help would be great.

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05-06-2005, 08:45 PM	#2
tougeC TougeMaster Join Date: Aug 2004 Location: Texas Posts: 150	lol im far from an expert but i would say get rid of the auto ecu.

05-06-2005, 11:49 PM	#3
insane ...are you? Join Date: Aug 2004 Posts: 89	I just found out my timing chain is loose, but would that cause the weird reving? I cant seem to find any info about this in my fsm.

05-07-2005, 06:24 AM	#4
TeamSLIPdrifter Nice rx7, is it 4 or 6cyl Join Date: Jul 2004 Location: Bartlett, Illinois Posts: 154	lol get that ecu out of there...

05-08-2005, 02:30 PM	#5
insane ...are you? Join Date: Aug 2004 Posts: 89	do you guys think my ecu is broken or do you think I just need a 5 speed ecu because I now have a 5 speed tranny unless it is malfunctioning the ecu should not be a problem because the car was giving me these problems when it still had the auto tranny.

05-08-2005, 04:27 PM	#6
TeamFazzne User Join Date: Mar 2005 Posts: 15	i dont think that it has anything to do with the auto ecu. i have a manual and it does the same thing. is there any aftermarket parts on your car?>

05-08-2005, 05:40 PM	#7
DriftspecCowboy User Join Date: May 2005 Location: Boulder, Colorado/Laramie, Wyoming Posts: 3	Check your IAC valve. I had the same problem.

05-08-2005, 07:31 PM	#8
GotNismo? But officer i swear.... Join Date: May 2004 Location: New Orleans Posts: 234	the timing would affect the jumps in the a/c but the 750-500 idle bounce, sounds like a vacuum leake somewhere. my rx7 used to do that.