Car has terrible idle needs tons of throttle to keep alive - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

blankets3 · 02-18-2021, 01:21 AM

Best way to share the video is from a reddit link

Sr20det s13 blacktop

https://www.reddit.com/r/240sx/comme...tm_name=iossmf

Im still not able to find the issue tho its winter now and the cars put away. Been trying to take it for safety but its been problem after problem

Silv1401 · 02-18-2021, 01:45 AM

So are you holding throttle to keep it idling around 1000, or is it just intermittently holding idle itself and then randomly dropping it?

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blankets3 · 02-18-2021, 08:34 AM

When you first start the car it seemes okay but starts to choke up and get worse and worse with more violent dips in rpm until you need to really lay on the throttle to prevent it from stalling (you can kinda hear an example of this in the video)

You need to keep the car alive with throttle on its own it will just stall

It doesnt smooth out or get better on its own

Silv1401 · 02-18-2021, 10:56 AM

I'm not particularly familiar with SR20s, however I do believe they suffered with IACV issues as well. Have you tried cleaning yours yet?

Also, it may be unlikely, but have you messed with the throttle body adjustments at all? Particularly the throttle plate's idle screw? If the car idles fine at first, it could be the iacv is working perfectly and regulating air on cold start like it's supposed to, but as the engine warms up, it is closing the IACV and beginning to rely more on the throttle plates ability to hold idle. However if it's not open enough, then it would be choking the engine, unless you open the throttle manually with the pedal.

Vac leak is also a possibilty, but that seems unlikely too. It would be an irregular idle from the get go, and dying on idle shouldn't be your problem, idling too high should. If it is a vac leak though, it would have to be one that is somehow closed for cold start, and then opens up after awhile. But that leak would have to be a big one to overpower the AFR enough to lean out and die.

Sent from my SM-N986U1 using Tapatalk

LtSlayer · 02-25-2021, 12:55 AM

start with the basics, test to make sure you maf is reading right. ask me if you need directions on this as i've done it multiple times. after that i would suspect a vacuum leak as well. an easy way to clean the IACV is to spray throttle body cleaner in there as it runs or spray a generous amount and let it sit for a while.

A common problem is boost leaks. If you don't have a boost gauge with a turbocharged car you're living life on hard mode for no reason. monitor your car and look cool at the same time, get one. They'll let you keep an eye on boost as well as tell you when you have a vacuum leak. vacuum should be ballpark 20 psi at idle. if it's below that then you likely have a leak

after that I'd suggest looking into your fpr and fuel pump. for these take off the lower vaccum line from the fpr. if it smells of gasoline, you need a new fpr.

get an inline pressure tester to make sure your fuel pump is good.

check your spark plugs as well becuase they'll tell you whether your car is rich or lean and then you can investigate the problems associated with them.

good luck

LtSlayer · 02-25-2021, 12:56 AM

i forgot to say the coolant temperature sensor can often play a role in this but theyre cheap and you may even be able to diagnose problems from your ECU if you have the switch to pull codes

Atill93 · 06-28-2021, 02:37 PM

bump. i'm dealing with the exact same issue now. did you figure out what it was?

02-18-2021, 01:21 AM	#1
blankets3 Join Date: Aug 2009 Location: Canada Posts: 20 Trader Rating: (0) Feedback Score: 0 reviews	Car has terrible idle needs tons of throttle to keep alive Best way to share the video is from a reddit link Sr20det s13 blacktop https://www.reddit.com/r/240sx/comme...tm_name=iossmf Im still not able to find the issue tho its winter now and the cars put away. Been trying to take it for safety but its been problem after problem

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02-18-2021, 01:45 AM	#2
Silv1401 Zilvia Member Join Date: Jan 2019 Location: Vancouver, WA/Portland, OR, USA Posts: 166 Trader Rating: (1) Feedback Score: 1 reviews	So are you holding throttle to keep it idling around 1000, or is it just intermittently holding idle itself and then randomly dropping it? Sent from my SM-N986U1 using Tapatalk

02-18-2021, 08:34 AM	#3
blankets3 Join Date: Aug 2009 Location: Canada Posts: 20 Trader Rating: (0) Feedback Score: 0 reviews	When you first start the car it seemes okay but starts to choke up and get worse and worse with more violent dips in rpm until you need to really lay on the throttle to prevent it from stalling (you can kinda hear an example of this in the video) You need to keep the car alive with throttle on its own it will just stall It doesnt smooth out or get better on its own

02-18-2021, 10:56 AM	#4
Silv1401 Zilvia Member Join Date: Jan 2019 Location: Vancouver, WA/Portland, OR, USA Posts: 166 Trader Rating: (1) Feedback Score: 1 reviews	I'm not particularly familiar with SR20s, however I do believe they suffered with IACV issues as well. Have you tried cleaning yours yet? Also, it may be unlikely, but have you messed with the throttle body adjustments at all? Particularly the throttle plate's idle screw? If the car idles fine at first, it could be the iacv is working perfectly and regulating air on cold start like it's supposed to, but as the engine warms up, it is closing the IACV and beginning to rely more on the throttle plates ability to hold idle. However if it's not open enough, then it would be choking the engine, unless you open the throttle manually with the pedal. Vac leak is also a possibilty, but that seems unlikely too. It would be an irregular idle from the get go, and dying on idle shouldn't be your problem, idling too high should. If it is a vac leak though, it would have to be one that is somehow closed for cold start, and then opens up after awhile. But that leak would have to be a big one to overpower the AFR enough to lean out and die. Sent from my SM-N986U1 using Tapatalk

02-25-2021, 12:55 AM	#5
LtSlayer Leaky Injector Join Date: Jul 2020 Location: Norco Posts: 68 Trader Rating: (0) Feedback Score: 0 reviews	start with the basics, test to make sure you maf is reading right. ask me if you need directions on this as i've done it multiple times. after that i would suspect a vacuum leak as well. an easy way to clean the IACV is to spray throttle body cleaner in there as it runs or spray a generous amount and let it sit for a while. A common problem is boost leaks. If you don't have a boost gauge with a turbocharged car you're living life on hard mode for no reason. monitor your car and look cool at the same time, get one. They'll let you keep an eye on boost as well as tell you when you have a vacuum leak. vacuum should be ballpark 20 psi at idle. if it's below that then you likely have a leak after that I'd suggest looking into your fpr and fuel pump. for these take off the lower vaccum line from the fpr. if it smells of gasoline, you need a new fpr. get an inline pressure tester to make sure your fuel pump is good. check your spark plugs as well becuase they'll tell you whether your car is rich or lean and then you can investigate the problems associated with them. good luck

02-25-2021, 12:56 AM	#6
LtSlayer Leaky Injector Join Date: Jul 2020 Location: Norco Posts: 68 Trader Rating: (0) Feedback Score: 0 reviews	i forgot to say the coolant temperature sensor can often play a role in this but theyre cheap and you may even be able to diagnose problems from your ECU if you have the switch to pull codes

06-28-2021, 02:37 PM	#7
Atill93 Leaky Injector Join Date: Jul 2012 Location: Alabama Age: 28 Posts: 144 Trader Rating: (0) Feedback Score: 0 reviews	bump. i'm dealing with the exact same issue now. did you figure out what it was?