Wants to stall when cold, idles fine when warm - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Shigun · 08-03-2014, 02:52 PM

As the title says, when my car is cold it wants to stall unless I constantly give it gas. Once it fully warms up, it's perfectly fine, seems to have no issues, can idle just fine right around 800-850rpms.

I've checked the TPS, it's sitting at about 0.44v. IACV is adjusted to ~750RPMs at 15 degrees timing in base idle adjustment mode, and as soon as I plug the TPS back in the idle goes to the normal 800-850.

I am not inclined to think it's the CTS, as I am not having any hot start issues outside of an issue that I have had for a bit where I need to tap the throttle once or twice just when starting, but that is something I need to do on both cold and hot start.

I don't *think* it's the IACV as, from my understanding, that generally seems to affect when it's warm and not when it's cold. Feel free to correct me on that if I am wrong, but I have cleaned the IACV before and it didn't resolve the issue.

If I adjust the IACV up then the problem doesn't exist, but I idle around 1-1.2k.

AFR seems to be normal, hovering around 14.3-15.2 at idle and cruising, going to about 12 at WOT.

l adam l · 08-03-2014, 08:04 PM

Quote:

Originally Posted by Shigun

I don't *think* it's the IACV as, from my understanding, that generally seems to affect when it's warm and not when it's cold. Feel free to correct me on that if I am wrong, but I have cleaned the IACV before and it didn't resolve the issue.

If I adjust the IACV up then the problem doesn't exist, but I idle around 1-1.2k.

have you tried putting 12v to it to see if it opens and closes(should take a while to close)? my rb20 had this problem and it was the iacv, i cleaned it and put it back in. still didn't fix the problem, so i put the 12v to it and it did nothing. ordered a used one and put it on and it idled fine.

Shigun · 08-04-2014, 12:22 AM

Quote:

Originally Posted by l adam l

have you tried putting 12v to it to see if it opens and closes(should take a while to close)? my rb20 had this problem and it was the iacv, i cleaned it and put it back in. still didn't fix the problem, so i put the 12v to it and it did nothing. ordered a used one and put it on and it idled fine.

I'll pull it off and test that out. Thanks for the idea, greatly appreciated.

Shigun · 08-04-2014, 09:13 AM

Discovered that my throttle body does not have the fast idle cam. I'm not sure how much this would affect everything on the basis of it wanting to stumble all the way up through it being fully warm. Anybody have insight on that?

Keeping in mind that I live in an area where the temperatures are about 99* right now, so I don't know how much that fast idle cam comes into play here.

NoPistons! · 08-14-2014, 08:08 AM

It's normal then. Most cars i have removed the idle control parts/emissions parts off of i've had to take 2-3 cranks to start and i have to have my foot slightly cracking the butterfly. My current car is like that. It's annoying. When coolant temps are below 75* it can take a while before it decides it wants to idle on it's own. I'm not using fast idle or an idle air control valve and haven't on my last two cars. Both do what your car describes. one was one stock ecu, other is on stand alone.

Croustibat · 08-14-2014, 08:38 AM

You could adjust it by changing the way idle is handled in the ECU, but you need to see a tuner to do that (or you could do it yourself if you know). I use a nistune, and there are some parameters about cold management. I added more timing vs temp on the cold part so it basically accelerates by itself and does not want to stall. I also activated the fuel recovery a bit higher: the ECU cuts fuel when releasing the accelerator under a rpm threshold, then enables it again when reaching a lower one. This way it does not dip when reaching a stop. amongst other things, idling and dip problems can occur when the gearbox neutral sensor does not work. Hope it helps.

JesterX18 · 08-18-2014, 01:47 PM

Mine was doing the same. I sprayed some carb cleaner in the iacv hose(big hose) when running it at a high idle and it greatly improved. no stalling anymore... if it gets better but doesn't completely go away, take it apart and clean it and or replace it.

Shigun · 08-18-2014, 01:48 PM

Yeah, mine wasn't the IACV, it was actually the fact that there was a pretty major hose missing, and I needed to recirc.

08-03-2014, 02:52 PM	#1
Shigun Leaky Injector Join Date: Jun 2011 Location: United States Age: 36 Posts: 118 Trader Rating: (1) Feedback Score: 1 reviews	Wants to stall when cold, idles fine when warm As the title says, when my car is cold it wants to stall unless I constantly give it gas. Once it fully warms up, it's perfectly fine, seems to have no issues, can idle just fine right around 800-850rpms. I've checked the TPS, it's sitting at about 0.44v. IACV is adjusted to ~750RPMs at 15 degrees timing in base idle adjustment mode, and as soon as I plug the TPS back in the idle goes to the normal 800-850. I am not inclined to think it's the CTS, as I am not having any hot start issues outside of an issue that I have had for a bit where I need to tap the throttle once or twice just when starting, but that is something I need to do on both cold and hot start. I don't think it's the IACV as, from my understanding, that generally seems to affect when it's warm and not when it's cold. Feel free to correct me on that if I am wrong, but I have cleaned the IACV before and it didn't resolve the issue. If I adjust the IACV up then the problem doesn't exist, but I idle around 1-1.2k. AFR seems to be normal, hovering around 14.3-15.2 at idle and cruising, going to about 12 at WOT.

08-14-2014, 08:08 AM	#5
NoPistons! Zilvia Junkie Join Date: Jan 2009 Location: Carolina Posts: 548 Trader Rating: (1) Feedback Score: 1 reviews	It's normal then. Most cars i have removed the idle control parts/emissions parts off of i've had to take 2-3 cranks to start and i have to have my foot slightly cracking the butterfly. My current car is like that. It's annoying. When coolant temps are below 75* it can take a while before it decides it wants to idle on it's own. I'm not using fast idle or an idle air control valve and haven't on my last two cars. Both do what your car describes. one was one stock ecu, other is on stand alone. __________________ Just another broke ass drifter

08-18-2014, 01:48 PM	#8
Shigun Leaky Injector Join Date: Jun 2011 Location: United States Age: 36 Posts: 118 Trader Rating: (1) Feedback Score: 1 reviews	Yeah, mine wasn't the IACV, it was actually the fact that there was a pretty major hose missing, and I needed to recirc. Last edited by Shigun; 08-18-2014 at 03:26 PM..

08-04-2014, 09:13 AM	#4
Shigun Leaky Injector Join Date: Jun 2011 Location: United States Age: 36 Posts: 118 Trader Rating: (1) Feedback Score: 1 reviews	Discovered that my throttle body does not have the fast idle cam. I'm not sure how much this would affect everything on the basis of it wanting to stumble all the way up through it being fully warm. Anybody have insight on that? Keeping in mind that I live in an area where the temperatures are about 99* right now, so I don't know how much that fast idle cam comes into play here.

08-14-2014, 08:38 AM	#6
Croustibat Nissanaholic! Join Date: Aug 2011 Location: France - Toulouse Age: 43 Posts: 1,851 Trader Rating: (0) Feedback Score: 0 reviews	You could adjust it by changing the way idle is handled in the ECU, but you need to see a tuner to do that (or you could do it yourself if you know). I use a nistune, and there are some parameters about cold management. I added more timing vs temp on the cold part so it basically accelerates by itself and does not want to stall. I also activated the fuel recovery a bit higher: the ECU cuts fuel when releasing the accelerator under a rpm threshold, then enables it again when reaching a lower one. This way it does not dip when reaching a stop. amongst other things, idling and dip problems can occur when the gearbox neutral sensor does not work. Hope it helps.

08-18-2014, 01:47 PM	#7
JesterX18 Join Date: Feb 2013 Location: Clifton Park, NY Age: 34 Posts: 34 Trader Rating: (2) Feedback Score: 2 reviews	Mine was doing the same. I sprayed some carb cleaner in the iacv hose(big hose) when running it at a high idle and it greatly improved. no stalling anymore... if it gets better but doesn't completely go away, take it apart and clean it and or replace it.