sr20det Swap Bogging out after startup, ok after a little throttle??? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

t.vo408 · 05-27-2010, 09:55 PM

So I just finished the swap and it ran fine for the first day. The second day, right after cranking it starts fine but then idle drops and finally stalls. But it will be OK if I keep the rpms at about 1500 for about 10-15 seconds its fine and runs ok. Sometimes at lights the idle will wander from about 1000-600 rpms. If I turn the motor off and start it right after the problem occurs again, will stall if I don't keep the revs up for a little.

Pretty weird that it runs fine after keeping revs up, but the problem immediately occurs again if I turn the car off and back on. Any ideas? Also what should idle be?

t.vo408 · 05-27-2010, 11:32 PM

I'm thinking it might be a vacuum leak, would that cause it? I opened the hood and can hear a slight hissing noise coming from the turbo side. Also when I let off throttle vacuum does to -20mmhg and then rises up to -15 so both those lead to a leak. So I'll investigate tomorrow when there's some light out.

ddf2006 · 05-27-2010, 11:41 PM

for sure it is ur mass air flow sensor
this happined to my ka
randomly wen im driving it will bog and go slow then speed up
and wen i came to a stop sometimes the idle will jump up and down and turn off
for sure replace it and ur good

t.vo408 · 05-28-2010, 12:03 AM

Sweet, I'm gonna try to fix the vacuum leak tomorrow, then clean the maf (spray carb cleaner on it or something) and spray some carb cleaner into the IACV tube near the tb and see what happens.

I just tried starting it up and it started no problem without dieing..... So it might also be a temperature thing, it was really hot earlier today. My gauge pretty much reads hot all the time like maximum, but that also happened when I had a KA so I'm not really sure whats going on there. Running stock sr20 rad and clutch fan.

dopplganger1 · 05-28-2010, 09:43 PM

do not use carb carb cleaner on your maf they have a special spray for it

lazysk8er2 · 05-28-2010, 10:25 PM

check your coolant temp sensor

t.vo408 · 05-29-2010, 01:36 AM

I am like 90% sure this is a vacuum leak... But my temp gauge is still jacked. By coolant temp do you mean this one?

FAE KA/SR Dash Gauge Temperature Sensor S13 Chassis

Or the one that talks to the ecu?

lazysk8er2 · 05-29-2010, 07:06 AM

the one going into the motor.

05-27-2010, 09:55 PM	#1
t.vo408 Join Date: Apr 2010 Location: CA Posts: 47 Trader Rating: (0) Feedback Score: 0 reviews	sr20det Swap Bogging out after startup, ok after a little throttle??? So I just finished the swap and it ran fine for the first day. The second day, right after cranking it starts fine but then idle drops and finally stalls. But it will be OK if I keep the rpms at about 1500 for about 10-15 seconds its fine and runs ok. Sometimes at lights the idle will wander from about 1000-600 rpms. If I turn the motor off and start it right after the problem occurs again, will stall if I don't keep the revs up for a little. Pretty weird that it runs fine after keeping revs up, but the problem immediately occurs again if I turn the car off and back on. Any ideas? Also what should idle be?

05-27-2010, 11:32 PM	#2
t.vo408 Join Date: Apr 2010 Location: CA Posts: 47 Trader Rating: (0) Feedback Score: 0 reviews	I'm thinking it might be a vacuum leak, would that cause it? I opened the hood and can hear a slight hissing noise coming from the turbo side. Also when I let off throttle vacuum does to -20mmhg and then rises up to -15 so both those lead to a leak. So I'll investigate tomorrow when there's some light out.

05-27-2010, 11:41 PM	#3
ddf2006 Zilvia Junkie Join Date: Jul 2009 Location: Moreno Valley Age: 32 Posts: 325 Trader Rating: (4) Feedback Score: 4 reviews	for sure it is ur mass air flow sensor this happined to my ka randomly wen im driving it will bog and go slow then speed up and wen i came to a stop sometimes the idle will jump up and down and turn off for sure replace it and ur good

05-28-2010, 12:03 AM	#4
t.vo408 Join Date: Apr 2010 Location: CA Posts: 47 Trader Rating: (0) Feedback Score: 0 reviews	Sweet, I'm gonna try to fix the vacuum leak tomorrow, then clean the maf (spray carb cleaner on it or something) and spray some carb cleaner into the IACV tube near the tb and see what happens. I just tried starting it up and it started no problem without dieing..... So it might also be a temperature thing, it was really hot earlier today. My gauge pretty much reads hot all the time like maximum, but that also happened when I had a KA so I'm not really sure whats going on there. Running stock sr20 rad and clutch fan.

05-28-2010, 09:43 PM	#5
dopplganger1 Zilvia Member Join Date: Jan 2008 Location: portland Posts: 235 Trader Rating: (1) Feedback Score: 1 reviews	do not use carb carb cleaner on your maf they have a special spray for it

05-29-2010, 01:36 AM	#7
t.vo408 Join Date: Apr 2010 Location: CA Posts: 47 Trader Rating: (0) Feedback Score: 0 reviews	I am like 90% sure this is a vacuum leak... But my temp gauge is still jacked. By coolant temp do you mean this one? FAE KA/SR Dash Gauge Temperature Sensor S13 Chassis Or the one that talks to the ecu?