SR20DET idles extremely rich and stalls - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Nikzilla · 12-19-2013, 12:13 PM

Hi guys!

I just put my motor back together and I'm trying to get the car running right.

It's an S13 blacktop with FMIC, 3 inch turbo-back and some aftermarket fans (bought this car recently).

I just did a bit of work on the motor, mostly maintenance and cleaning.
I installed RAS, fuel pressure sensor (T'ed off after fuel filter), wideband oxygen sensor bung, and tapped a boost gauge line into the intake manifold collector. (note: I didn't wire up the gauges yet)
The work involved dis-assembly of the intake manifold collector, and valvetrain.

The car fires right up, and runs fine (sounds a bit wierd though) for about 10sec, after which it just bogs and dies.
If I tap the gas as it's bogging, it will rev up normally, and as soon as the RPM's return, it bogs and dies again.

My narrowband gauge (which I'm not sure if it's working because the purple wire is disconnected for it), is pretty much bottoming out on the rich side, and the plugs are wet and reek of fuel.

Disconnecting MAF makes no difference, and when I pinched the fuel hose, it just died quicker.

When I was reassembling the valvetrain, I was a bit skeptical as to whether I got the alignment marks correct on the timing chain, because at TDC the keyhole for the exhaust camshaft isn't dead on 12 o'clock, it's more like 12:30. But unfortunately it doesn't idle steady enough for me to check timing yet.

Don't think it's a vacuum leak because the car should run lean instead of rich, and don't think timing would cause a rich condition.

Any advice?

Thanks!

ultimateirving · 12-19-2013, 12:31 PM

Vacuum leak is what it sounds like to me, especially when it dies returning to idle. For sure pressurize the system and make sure there is no hissing or leaks anywhere.
Its an easy test to do and will at least verify that everything is hooked up right

Nikzilla · 12-19-2013, 12:51 PM

Quote:

Originally Posted by ultimateirving

Vacuum leak is what it sounds like to me, especially when it dies returning to idle. For sure pressurize the system and make sure there is no hissing or leaks anywhere.
Its an easy test to do and will at least verify that everything is hooked up right

I don't have any way to pressurize it, but I'll check for leaks using the carb cleaner method once I get home.

I'm just wondering, wouldn't it run lean from a vacuum leak?

ultimateirving · 12-19-2013, 05:27 PM

Quote:

Originally Posted by Nikzilla

I don't have any way to pressurize it, but I'll check for leaks using the carb cleaner method once I get home.

I'm just wondering, wouldn't it run lean from a vacuum leak?

all the times ive had couplers pop off and such, it runs pig rich.

And are you saying you dont have an air compressor?
Ive used a bike pump with a boost leak tester and so you surely can think of something.. The spray method isnt very reliable i feel

Nikzilla · 12-19-2013, 05:59 PM

Quote:

Originally Posted by ultimateirving

all the times ive had couplers pop off and such, it runs pig rich.

And are you saying you dont have an air compressor?
Ive used a bike pump with a boost leak tester and so you surely can think of something.. The spray method isnt very reliable i feel

Yeah I don't have an air compressor. Bike pump might be a good idea.

Nikzilla · 12-20-2013, 02:23 AM

Ok, I did the cigar test and found a leak.

Fixed it, starter her up, same exact thing happened.

Should I use the bicycle pump method and check for more leaks, or do you think it's something else?

TheRealSy90 · 12-20-2013, 03:22 AM

Is your factory o2 sensor even connected? And a narrowband gauge is worthless.

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OnTheChip · 12-20-2013, 08:27 AM

"Disconnecting MAF makes no difference" might be a clue to the problem.

Nikzilla · 12-20-2013, 01:22 PM

I'm gunna wire up my gauges tonight to see what's up with the fuel pressure and AFR. Maybe that will shed some light.

Nikzilla · 12-21-2013, 09:20 PM

Ok. Fuel pressure was nominal.

After firing up, afr was at about 13, it was jumping around steadily leaning itself out untill it hit 18, then bottomed out at 20 and stalled.

Guess you were right. I'll check for leaks with a bike pump.

Kingtal0n · 12-21-2013, 10:00 PM

boost leak

Nikzilla · 12-22-2013, 02:00 PM

So I did find another leak, but the problem persisited. I then discovered that the turbo elbow is bolted in by only 2 bolts, and there is a visible gap between the turbo outlet and the elbow where you can see a lot of the exhaust leaking out. (I bought this car recently).

Since the car runs fine, but then gradually leans out, could it be that the incomplete exhaust signature hitting the o2 sensor leans out the fuel trim untill the car stalls?

Nikzilla · 12-23-2013, 03:13 AM

Ok, elbow bolted in, same thing.

However, I was actually able to get a read with the timing light this time, and it was reading at like 50 degrees retarded, and right as it was about to die, I turned the CAS to set the timing to like 35 degrees (maxed out the CAS), and it stabilized.

I now realize that the reason I thought it was getting weird fuel was because the O2 sensor was getting false readings because of the turbo elbow issue, but in reality the CAS is off by a tooth.

12-19-2013, 12:13 PM	#1
Nikzilla Zilvia Member Join Date: Jun 2013 Location: Los Angeles Age: 30 Posts: 291 Trader Rating: (0) Feedback Score: 0 reviews	SR20DET idles extremely rich and stalls Hi guys! I just put my motor back together and I'm trying to get the car running right. It's an S13 blacktop with FMIC, 3 inch turbo-back and some aftermarket fans (bought this car recently). I just did a bit of work on the motor, mostly maintenance and cleaning. I installed RAS, fuel pressure sensor (T'ed off after fuel filter), wideband oxygen sensor bung, and tapped a boost gauge line into the intake manifold collector. (note: I didn't wire up the gauges yet) The work involved dis-assembly of the intake manifold collector, and valvetrain. The car fires right up, and runs fine (sounds a bit wierd though) for about 10sec, after which it just bogs and dies. If I tap the gas as it's bogging, it will rev up normally, and as soon as the RPM's return, it bogs and dies again. My narrowband gauge (which I'm not sure if it's working because the purple wire is disconnected for it), is pretty much bottoming out on the rich side, and the plugs are wet and reek of fuel. Disconnecting MAF makes no difference, and when I pinched the fuel hose, it just died quicker. When I was reassembling the valvetrain, I was a bit skeptical as to whether I got the alignment marks correct on the timing chain, because at TDC the keyhole for the exhaust camshaft isn't dead on 12 o'clock, it's more like 12:30. But unfortunately it doesn't idle steady enough for me to check timing yet. Don't think it's a vacuum leak because the car should run lean instead of rich, and don't think timing would cause a rich condition. Any advice? Thanks!

12-19-2013, 12:31 PM	#2
ultimateirving Zilvia FREAK! Join Date: Nov 2010 Location: arizona Age: 37 Posts: 1,521 Trader Rating: (1) Feedback Score: 1 reviews	Vacuum leak is what it sounds like to me, especially when it dies returning to idle. For sure pressurize the system and make sure there is no hissing or leaks anywhere. Its an easy test to do and will at least verify that everything is hooked up right __________________ Z32 with lq4 swap Desert Street Scene \|\| Dssevents.com

12-20-2013, 08:27 AM	#8
OnTheChip Zilvia Junkie Join Date: May 2013 Location: Burgaw, NC Posts: 318 Trader Rating: (0) Feedback Score: 0 reviews	"Disconnecting MAF makes no difference" might be a clue to the problem. __________________ NismotronicSA - Speed-Density Tuning for Nissans

12-21-2013, 10:00 PM	#11
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 42 Posts: 4,829 Trader Rating: (17) Feedback Score: 17 reviews	boost leak __________________ 5.3/4l80e/turbo 240sx playthrough: tinyurl.com/4l80er

12-22-2013, 02:00 PM	#12
Nikzilla Zilvia Member Join Date: Jun 2013 Location: Los Angeles Age: 30 Posts: 291 Trader Rating: (0) Feedback Score: 0 reviews	So I did find another leak, but the problem persisited. I then discovered that the turbo elbow is bolted in by only 2 bolts, and there is a visible gap between the turbo outlet and the elbow where you can see a lot of the exhaust leaking out. (I bought this car recently). Since the car runs fine, but then gradually leans out, could it be that the incomplete exhaust signature hitting the o2 sensor leans out the fuel trim untill the car stalls? Last edited by Nikzilla; 12-22-2013 at 02:38 PM..

12-20-2013, 02:23 AM	#6
Nikzilla Zilvia Member Join Date: Jun 2013 Location: Los Angeles Age: 30 Posts: 291 Trader Rating: (0) Feedback Score: 0 reviews	Ok, I did the cigar test and found a leak. Fixed it, starter her up, same exact thing happened. Should I use the bicycle pump method and check for more leaks, or do you think it's something else?

12-20-2013, 01:22 PM	#9
Nikzilla Zilvia Member Join Date: Jun 2013 Location: Los Angeles Age: 30 Posts: 291 Trader Rating: (0) Feedback Score: 0 reviews	I'm gunna wire up my gauges tonight to see what's up with the fuel pressure and AFR. Maybe that will shed some light.

12-21-2013, 09:20 PM	#10
Nikzilla Zilvia Member Join Date: Jun 2013 Location: Los Angeles Age: 30 Posts: 291 Trader Rating: (0) Feedback Score: 0 reviews	Ok. Fuel pressure was nominal. After firing up, afr was at about 13, it was jumping around steadily leaning itself out untill it hit 18, then bottomed out at 20 and stalled. Guess you were right. I'll check for leaks with a bike pump.

12-23-2013, 03:13 AM	#13
Nikzilla Zilvia Member Join Date: Jun 2013 Location: Los Angeles Age: 30 Posts: 291 Trader Rating: (0) Feedback Score: 0 reviews	Ok, elbow bolted in, same thing. However, I was actually able to get a read with the timing light this time, and it was reading at like 50 degrees retarded, and right as it was about to die, I turned the CAS to set the timing to like 35 degrees (maxed out the CAS), and it stabilized. I now realize that the reason I thought it was getting weird fuel was because the O2 sensor was getting false readings because of the turbo elbow issue, but in reality the CAS is off by a tooth.