Sporadic Idle and Throttle response - TriStateTuners.com :: Home of Tristate Auto Enthusiast

mrball0u · 09-08-2011, 12:45 AM

The car in question is a 1990 nissan 300zx. Non turbo.

The problem - A few weeks ago my father and i decided to tackle my high idle issue (1500) and see if we could get it down a bit lower. Several things are done to the car which could be the cause of such a high average idle. After all tinkering was done the car idled at about 1300. I drove the car maybe a mile or two to my girlfriends house and it was fine. the car sat there overnight and when i went to leave for work the next morning idle seemed to go up and down without any driver response. It eventually went away, but came back short after at a red light. i went to accelerate and shifted as usual but as i let off to shift into third i lost all power. With my foot to the ground and a line of cars behind me i pulled to the side as the rpms rose and fell sporadically. i finally was fed up with it and adjusted the idle back to normal which seemed to be a temporary solution. but the problem has arrisen again. Ive searched all over. tinkered with the idle and adjusted it on both sides and cleaned the MAF and filter. the car seems to only do it when the throttle is engaged from the cockpit. Is this an electrical bug or a sensor? or maybe something else.... i'm stumped. And it gets real old going down the highway in fifth gear and losing all power....

any input is greatly appreciated.

jpalamar · 09-08-2011, 10:52 AM

What exactly have you done so far to check things out?

fitftw · 09-08-2011, 11:16 AM

my money is on vacuum leak.

mrball0u · 09-08-2011, 02:19 PM

I took the nose piece off and cleaned the maf and filter because one post on NICO said that it may be the MAF. I searched for visible vaccuum leaks before the problem even started and had found one that was taken care of but it never affected anything.

Messing with the calibration on the two idle screws seemed to work for a little but then it came back. I had backed both screws all the way out and retightened them to be even and adjusted accordingly.

Someone said it may be the TPS or the Idle sensors, or even the ecu.

Reds82 · 09-08-2011, 05:12 PM

Sounds a lot like a big vaccum leak after the maf or throttle body spray a little start fluid around them see if it bogs or revs if it does you found your leak

mrball0u · 09-11-2011, 08:07 PM

I sprayed around and checked for more leaks and didnt find any. I happened to have the motivation to mess with my throttle assembly and all the idle screws again. I seemed to have fixed the problem by adjusting the right side.

09-08-2011, 12:45 AM	#1
mrball0u Tri-State Training Wheels Join Date: Jul 2011 Location: Gilbertsville Member #21359 My Ride: 1990 Z32 - 2003 G35 COUPE iTrader: (0)	Sporadic Idle and Throttle response The car in question is a 1990 nissan 300zx. Non turbo. The problem - A few weeks ago my father and i decided to tackle my high idle issue (1500) and see if we could get it down a bit lower. Several things are done to the car which could be the cause of such a high average idle. After all tinkering was done the car idled at about 1300. I drove the car maybe a mile or two to my girlfriends house and it was fine. the car sat there overnight and when i went to leave for work the next morning idle seemed to go up and down without any driver response. It eventually went away, but came back short after at a red light. i went to accelerate and shifted as usual but as i let off to shift into third i lost all power. With my foot to the ground and a line of cars behind me i pulled to the side as the rpms rose and fell sporadically. i finally was fed up with it and adjusted the idle back to normal which seemed to be a temporary solution. but the problem has arrisen again. Ive searched all over. tinkered with the idle and adjusted it on both sides and cleaned the MAF and filter. the car seems to only do it when the throttle is engaged from the cockpit. Is this an electrical bug or a sensor? or maybe something else.... i'm stumped. And it gets real old going down the highway in fifth gear and losing all power.... any input is greatly appreciated. __________________ 1990 Z32 2+0 (PARTING OUT) 2003 SILVER G35 COUPE

09-08-2011, 11:16 AM	#3
fitftw Tri-State Post Whore Join Date: Dec 2009 Location: CNJ Member #15351 My Ride: 96 Miata 2,040lbs full tank, hardtop, half-cage iTrader: (0)	my money is on vacuum leak. __________________ 96 Miata gutted toy car 94 Shadow DD To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures. To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.

09-08-2011, 02:19 PM	#4
mrball0u Tri-State Training Wheels Join Date: Jul 2011 Location: Gilbertsville Member #21359 My Ride: 1990 Z32 - 2003 G35 COUPE iTrader: (0)	I took the nose piece off and cleaned the maf and filter because one post on NICO said that it may be the MAF. I searched for visible vaccuum leaks before the problem even started and had found one that was taken care of but it never affected anything. Messing with the calibration on the two idle screws seemed to work for a little but then it came back. I had backed both screws all the way out and retightened them to be even and adjusted accordingly. Someone said it may be the TPS or the Idle sensors, or even the ecu. __________________ 1990 Z32 2+0 (PARTING OUT) 2003 SILVER G35 COUPE

09-11-2011, 08:07 PM	#6
mrball0u Tri-State Training Wheels Join Date: Jul 2011 Location: Gilbertsville Member #21359 My Ride: 1990 Z32 - 2003 G35 COUPE iTrader: (0)	I sprayed around and checked for more leaks and didnt find any. I happened to have the motivation to mess with my throttle assembly and all the idle screws again. I seemed to have fixed the problem by adjusting the right side. __________________ 1990 Z32 2+0 (PARTING OUT) 2003 SILVER G35 COUPE

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09-08-2011, 10:52 AM	#2
jpalamar TST Ruined My Life! Join Date: May 2009 Location: Collegeville, PA Member #13773 My Ride: 03 Corvette Z06 iTrader: (3)	What exactly have you done so far to check things out?

09-08-2011, 05:12 PM	#5
Reds82 Tri-State Addict Join Date: Jan 2009 Location: Fogelsville Pa Member #10670 My Ride: 1981 Mercury Crappi iTrader: (2)	Sounds a lot like a big vaccum leak after the maf or throttle body spray a little start fluid around them see if it bogs or revs if it does you found your leak