KA24E rough start-up/idle. TPS? MAF? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

xkirex · 03-26-2012, 08:30 PM

Ok I've searched for 2 days trying to figure out what my problem is.

Heres what happend.

I replaced a leaking freeze plug on the intake side of the block which ment I took off the intake manifold and all the vacuum lines attached to it. I also swapped over another throttle body and had to swap over my TPS. After everything was put back together, I go to fire it up and it starts but quickly dies

I try again and this time give it some gas to keep it from dying and it stays on but idles really high. I messed with the TPS and got it start at around 1K but it idled really bad. Also at one point I forgot to plug in the maf and the car actually idled better but wouldnt let me rev passed 3K.

I swapped over a known good TPS and MAF from my brothers car and I still get this. Did I install the TPS wrong.

I am also sure I dont have a vaccuum leak cuz I sprayed carb cleaner around with no spike in revs.

Heres a video I took just to show what im talking about.

240sx idle problem - YouTube

Thanks in advance guys!

HieuHundreds · 03-28-2012, 01:00 AM

spark plugs ? loosen the two big bolts on the distributor cap and play with that , also clean MAF, THROTTLE BODY AND IACV ( IDLE AIR CONTROL VALVE) that helped me.

tapdeznutz · 03-29-2012, 02:00 PM

i hope you know that you cant just adjust your tps like that and thing its cool. i would first back off the small flat head adjustor on right side of throttle body so you can more accurately adjust the tps to the 0.45 setting, etc. then verify timing the proper way by unplugging tps with timing gun. go from there. i had really crap idling when i had intake pipe and open air filter. when back to stock pipe and k&n drop in and my idle is much more stable. also try the seafoam procedure. i do that on a regular also. my engine still runs pretty good considering 280k on the clock.

santi5222 · 04-02-2012, 06:11 PM

fuel pump maybe a injector I had those types of problems in the past

xkirex · 04-02-2012, 06:15 PM

I found out what it was. Torn intake manifold in the plenum.

As far as tps adjustment. What are the exact procedure on adjusting the tps on a SOHC. I have a multimeter and all that snazz. I just need to find out the exact pins i need to read and what I have to disconnect to get a proper reading.

tapdeznutz · 04-04-2012, 02:04 PM

here is procedure for dohc:
Throttle Position Sensor Adjustment

but it should also apply to sohc...i have tried searching for sohc as well but never found one. just back probe the harness to find the 0.45-0.50 reading then you know you have the 2 correct leads. carefully loosen the 2 bolts holding the tps and make micro adjustments. one thing i want to know is make sure your throttle plate adjustment screw is backed off, since i know i have played with this in the past to increase idle...i am sure some of us have done the same thing...just saying.

03-26-2012, 08:30 PM	#1
xkirex Zilvia Member Join Date: Apr 2011 Location: Pomona Posts: 225 Trader Rating: (7) Feedback Score: 7 reviews	KA24E rough start-up/idle. TPS? MAF? Ok I've searched for 2 days trying to figure out what my problem is. Heres what happend. I replaced a leaking freeze plug on the intake side of the block which ment I took off the intake manifold and all the vacuum lines attached to it. I also swapped over another throttle body and had to swap over my TPS. After everything was put back together, I go to fire it up and it starts but quickly dies I try again and this time give it some gas to keep it from dying and it stays on but idles really high. I messed with the TPS and got it start at around 1K but it idled really bad. Also at one point I forgot to plug in the maf and the car actually idled better but wouldnt let me rev passed 3K. I swapped over a known good TPS and MAF from my brothers car and I still get this. Did I install the TPS wrong. I am also sure I dont have a vaccuum leak cuz I sprayed carb cleaner around with no spike in revs. Heres a video I took just to show what im talking about. 240sx idle problem - YouTube Thanks in advance guys!

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03-28-2012, 01:00 AM	#2
HieuHundreds Join Date: Feb 2012 Location: york , pennsylvania Posts: 47 Trader Rating: (0) Feedback Score: 0 reviews	spark plugs ? loosen the two big bolts on the distributor cap and play with that , also clean MAF, THROTTLE BODY AND IACV ( IDLE AIR CONTROL VALVE) that helped me.

03-29-2012, 02:00 PM	#3
tapdeznutz Nissanaholic! Join Date: May 2011 Location: Long Beach Age: 41 Posts: 1,801 Trader Rating: (50) Feedback Score: 50 reviews	i hope you know that you cant just adjust your tps like that and thing its cool. i would first back off the small flat head adjustor on right side of throttle body so you can more accurately adjust the tps to the 0.45 setting, etc. then verify timing the proper way by unplugging tps with timing gun. go from there. i had really crap idling when i had intake pipe and open air filter. when back to stock pipe and k&n drop in and my idle is much more stable. also try the seafoam procedure. i do that on a regular also. my engine still runs pretty good considering 280k on the clock.

04-02-2012, 06:11 PM	#4
santi5222 Join Date: May 2008 Location: miami Age: 33 Posts: 14 Trader Rating: (0) Feedback Score: 0 reviews	fuel pump maybe a injector I had those types of problems in the past

04-02-2012, 06:15 PM	#5
xkirex Zilvia Member Join Date: Apr 2011 Location: Pomona Posts: 225 Trader Rating: (7) Feedback Score: 7 reviews	I found out what it was. Torn intake manifold in the plenum. As far as tps adjustment. What are the exact procedure on adjusting the tps on a SOHC. I have a multimeter and all that snazz. I just need to find out the exact pins i need to read and what I have to disconnect to get a proper reading.

04-04-2012, 02:04 PM	#6
tapdeznutz Nissanaholic! Join Date: May 2011 Location: Long Beach Age: 41 Posts: 1,801 Trader Rating: (50) Feedback Score: 50 reviews	here is procedure for dohc: Throttle Position Sensor Adjustment but it should also apply to sohc...i have tried searching for sohc as well but never found one. just back probe the harness to find the 0.45-0.50 reading then you know you have the 2 correct leads. carefully loosen the 2 bolts holding the tps and make micro adjustments. one thing i want to know is make sure your throttle plate adjustment screw is backed off, since i know i have played with this in the past to increase idle...i am sure some of us have done the same thing...just saying.