Failed idle air learning, stalled, won't start!

nismoZium · 07-18-2018, 01:29 AM

Hi all,

I recently got my car on the road and have been knocking out one small gremlin at a time. My idle has been a bit on the high side since getting my GTM TT setup plumbed correctly, and so I decided to pull up Nissan Datascan with my BT OBD adapter and re-learn the idle air.

I started the car without issue as normal and let it warm up. Cleared the self learning, and then a few minutes later tried the idle air learning. It mailed/timed out. I shut the car down, let it sit for a minute, and fired it back up. Idle was rock solid and so I tried again. This time mid procedure the idle stumbled and the car shut down. Now when I try to start it, I get the starter cranking away but it won't fire up.

Has anyone run into anything similar? It almost seems like a fuel issue, but that's a mighty big coincidence. Is there some master reset I can do or something similar? As always, any fingers pointing in the general right direction would be most appreciated!

nismoZium · 07-18-2018, 02:30 PM

Update:

Snuck home during my lunch break to try a few things, still no luck. I pulled each one of the crank position sensors (and then both) and tried to start - same symptoms. I threw a bottle of techron in the tank but my 5gal can is empty so I'll have to add more tonight. The only thing that strikes me as a little strange is when the motor is cranking and trying to start the battery gauge goes dim and down to nothing, and then pops back up to normal battery voltage (currently ~12.5V after some cranking) when it's done trying.

Still no DTCs other than the crank position ones from pulling them. Oh and I observed the belt in daylight - it's moving with the cranking sound of the starter, so the motor is turning.

SouthArk370Z · 07-18-2018, 05:15 PM

Check the volts at the battery while cranking. IIRC, about 10V is considered the minimum (maybe someone will chime in and confirm/deny that figure).

nismoZium · 07-18-2018, 11:36 PM

Quote:

Originally Posted by SouthArk370Z

Check the volts at the battery while cranking. IIRC, about 10V is considered the minimum (maybe someone will chime in and confirm/deny that figure).

The voltage at the battery was sticking at ~11.4 while cranking, so no shorts it would seem. The battery is also only about a month old, so I don't think that's it. I did notice that the normal "press clutch + button" message on the dash didn't display until after I put the car into ACC, which struck me as weird.

I also pulled two of the easiest-to-get-at plugs (the front L+R) and both had clean electrodes with a bit of black buildup on the nearest thread or two.

I think my next two checks will be the MAFs and then maybe fuel, though I can definitely hear the pump priming when I key-on.

nismoZium · 07-20-2018, 11:11 AM

Last night's update:

In a "this can't possibly work" attempt, I topped off the gas tank which was sitting at a little under 3/4. No dice.

I moved under the hood and did hear a weird whining sound with the car set to "ON" - I pulled out my stethoscope and determined it was the passenger side TPS motor. Pulling the plug silenced it, and so I pulled the intake pipe off of my throttle body and gave the valve a little nudge with my finger. Plugging the TPS back in was now quiet, but the car behaved the same.

Next up, spark checking. I pulled the #2 plug and coil pack and grounded the plug to the frame via aligator clip. Craking produced multiple sparks at what looked like a regular interval.

So I think tonight/this weekend I'll be checking fuel. I can hear the pump prime when I turn the car on, but could it possibly be a cracked hat or blockage? Or possibly something with the injectors? Even a fuse or relay perhaps?

If the fuel system checks out, then I might be bracing for something much worse internally...

nismoZium · 07-21-2018, 10:46 AM

Morning check-in: found one dead fuse in the IPDM....but it was for DRLs. Decided to pop the fuel dampener fitting and voila! Zero fuel pressure! Going to pull the pump and see what's what.

nismoZium · 07-21-2018, 10:21 PM

Well, mystery solved...and a silly one at that!

Thanks for following/commenting!

SouthArk370Z · 07-22-2018, 12:41 AM

Quote:

Originally Posted by nismoZium

Well, mystery solved...and a silly one at that!

Thanks for following/commenting!

07-18-2018, 01:29 AM	#1 (permalink)
nismoZium Base Member Join Date: Jan 2018 Location: Portland, OR Posts: 24 Drives: 12 Nissan 370z Nismo Rep Power: 7	Failed idle air learning, stalled, won't start! Hi all, I recently got my car on the road and have been knocking out one small gremlin at a time. My idle has been a bit on the high side since getting my GTM TT setup plumbed correctly, and so I decided to pull up Nissan Datascan with my BT OBD adapter and re-learn the idle air. I started the car without issue as normal and let it warm up. Cleared the self learning, and then a few minutes later tried the idle air learning. It mailed/timed out. I shut the car down, let it sit for a minute, and fired it back up. Idle was rock solid and so I tried again. This time mid procedure the idle stumbled and the car shut down. Now when I try to start it, I get the starter cranking away but it won't fire up. Has anyone run into anything similar? It almost seems like a fuel issue, but that's a mighty big coincidence. Is there some master reset I can do or something similar? As always, any fingers pointing in the general right direction would be most appreciated!

07-18-2018, 02:30 PM	#2 (permalink)
nismoZium Base Member Join Date: Jan 2018 Location: Portland, OR Posts: 24 Drives: 12 Nissan 370z Nismo Rep Power: 7	Update: Snuck home during my lunch break to try a few things, still no luck. I pulled each one of the crank position sensors (and then both) and tried to start - same symptoms. I threw a bottle of techron in the tank but my 5gal can is empty so I'll have to add more tonight. The only thing that strikes me as a little strange is when the motor is cranking and trying to start the battery gauge goes dim and down to nothing, and then pops back up to normal battery voltage (currently ~12.5V after some cranking) when it's done trying. Still no DTCs other than the crank position ones from pulling them. Oh and I observed the belt in daylight - it's moving with the cranking sound of the starter, so the motor is turning. Last edited by nismoZium; 07-18-2018 at 02:35 PM.

07-18-2018, 05:15 PM	#3 (permalink)
SouthArk370Z Premium Member Join Date: Nov 2010 Location: South Arkansas Posts: 8,435 Drives: 2014 Challenger Rep Power: 324197	Check the volts at the battery while cranking. IIRC, about 10V is considered the minimum (maybe someone will chime in and confirm/deny that figure). __________________ Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

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07-20-2018, 11:11 AM	#5 (permalink)
nismoZium Base Member Join Date: Jan 2018 Location: Portland, OR Posts: 24 Drives: 12 Nissan 370z Nismo Rep Power: 7	Last night's update: In a "this can't possibly work" attempt, I topped off the gas tank which was sitting at a little under 3/4. No dice. I moved under the hood and did hear a weird whining sound with the car set to "ON" - I pulled out my stethoscope and determined it was the passenger side TPS motor. Pulling the plug silenced it, and so I pulled the intake pipe off of my throttle body and gave the valve a little nudge with my finger. Plugging the TPS back in was now quiet, but the car behaved the same. Next up, spark checking. I pulled the #2 plug and coil pack and grounded the plug to the frame via aligator clip. Craking produced multiple sparks at what looked like a regular interval. So I think tonight/this weekend I'll be checking fuel. I can hear the pump prime when I turn the car on, but could it possibly be a cracked hat or blockage? Or possibly something with the injectors? Even a fuse or relay perhaps? If the fuel system checks out, then I might be bracing for something much worse internally...

07-21-2018, 10:46 AM	#6 (permalink)
nismoZium Base Member Join Date: Jan 2018 Location: Portland, OR Posts: 24 Drives: 12 Nissan 370z Nismo Rep Power: 7	Morning check-in: found one dead fuse in the IPDM....but it was for DRLs. Decided to pop the fuel dampener fitting and voila! Zero fuel pressure! Going to pull the pump and see what's what.

07-21-2018, 10:21 PM	#7 (permalink)
nismoZium Base Member Join Date: Jan 2018 Location: Portland, OR Posts: 24 Drives: 12 Nissan 370z Nismo Rep Power: 7	Well, mystery solved...and a silly one at that! Thanks for following/commenting!