The oddest thing happened this weekend. I went to move my car and when I turned the key it didn't start. It hummed like it was trying to crank but wouldn't until I physically pushed the gas pedal. They I had a hard time keeping it running.
Once I drove it down the road for about 20 mins or so and back it seems fine and back to normal. Was this a symptom of something terrible or just a fluke think?
Experts please opine.
Hard time starting and Rough Idle
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AlabamaDan
- Posts: 1750
- Joined: Fri Aug 02, 2002 12:37 pm
- Car: 2015 Infiniti Q70
1998 Infiniti QX4
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AlabamaDan
- Posts: 1750
- Joined: Fri Aug 02, 2002 12:37 pm
- Car: 2015 Infiniti Q70
1998 Infiniti QX4
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
BUT WHEN IT WAS LAST CRANKED [ Don't care if it sat for a month] HOW LONG DID IT LAST RUN? If you came in from a 15 minute minimum drive and turned it off and never moved it, that's ok, otherwise you may have created the problem with a short drive cycle.
FPCU = fuel pump control unit [3 speed pump motor controller].
The other thing to check is the fuel pressure decline as it sits for hours, days, years. There are antidrain back valves and the pressure should stay above 20 psi...........otherwise leaky injectors or something allowing pressure to dissipate......taking a few seconds to rebuild.
System designed to let the car sit at airport for at least 3 weeks.During cranking the ecu commands FPCU to go to high to rebuild pressure fast from 20 psi to 34 psi minimum.
FPCU = fuel pump control unit [3 speed pump motor controller].
The other thing to check is the fuel pressure decline as it sits for hours, days, years. There are antidrain back valves and the pressure should stay above 20 psi...........otherwise leaky injectors or something allowing pressure to dissipate......taking a few seconds to rebuild.
System designed to let the car sit at airport for at least 3 weeks.During cranking the ecu commands FPCU to go to high to rebuild pressure fast from 20 psi to 34 psi minimum.
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AlabamaDan
- Posts: 1750
- Joined: Fri Aug 02, 2002 12:37 pm
- Car: 2015 Infiniti Q70
1998 Infiniti QX4
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Well then it wasn't from the warm up cycle enrichment washing the rings.Check the leak down rate of rail pressure. If that's ok, pull and examine the ecterior/interior of FPCU for melted or discolored solder pads.......any signs of a over heat.Check enough things and you will find it.
Or wait for it to fail permanently after a flat bedding, we will find it.
What was the moon phase, planet alignment, graviometric field intensity..........lots of plausable other reasons.
I chased a minor problem on my Q for 2 years changed everything but the FPCU........finally it didn't chank a few months ago........no burn marks no visable defects just didn't work.
Or wait for it to fail permanently after a flat bedding, we will find it.
What was the moon phase, planet alignment, graviometric field intensity..........lots of plausable other reasons.
I chased a minor problem on my Q for 2 years changed everything but the FPCU........finally it didn't chank a few months ago........no burn marks no visable defects just didn't work.