Intermittent car stalling and low hunting idle, 2003 Z06, fuel level code
01-27-2014, 01:30 AM
#1
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Thread Starter
Intermittent car stalling and low hunting idle, 2003 Z06, fuel level code
As described in the title I have a worsening case of the intermittent "car shuts off randomly" mixed in with an intermittent low (500pm) hunting idle. It has occurred twice before yesterday, then it got really bad. My case seems a lot like this guy, which I think was a CKP case: http://forums.corvetteforum.com/c5-t...dm-u1016h.html. I posted some details below and am trying to figure out if this is a CKP problem, a Fuel Pump problem, or something else.
The car first did it about 4 months ago, literally as I finished driving across the country. Stall, failed restart, restart into a hunting idle for 10 seconds, resume normal idle and behaviour. No CEL.
Second case was about a week ago, with one instance of a hunting idle on startup, no stall. Later in that day I had the gas gauge stick to low fuel until I filled up. (It stuck to "low" when the tank was about at 1/4)
Third and terminal case was yesterday. Driving home from a lapping day the car went through increasingly frequent and consistent shutoff/restart cycles. I was barely able to limp home as the ratio of "good" to "bad" got progressively worse. At the end of the drive I was going one residential block at a time and dashing across intersections so that I wouldn't get stuck in them. The "bad" mode got consistent as I mentioned - If the throttle was open and the drivetrain was engaged the motor would lose all power. If the motor was not clutched to the drivetrain it would drop to a low hunting 500 rpm idle. Giving it throttle would kill it. After dying it would fail to restart once or twice and then eventually start working. Once I learned how to keep the motor running (do nothing, just wait for the bad spell to pass), it would eventually resume a normal idle and be able to move the car. This repeated in ever shorter cycles. Much earlier in this drive the fuel gauge had stuck to "low" at nearly a full tank.
Currently the car has one code set, P1431 H, C and the fuel gauge still reads low. There are no other codes in history and the battery has not been unplugged for some time. The car blew a very clean emissions test back in September.
Corvette forum literature review seems to point down two roads - fuel pump or crank position sensor. I don't have any of the kit necessary to diagnose it, so I was looking for some thoughts before I buy anything.
I have two questions for the forum:
1. Anything else I should consider?
2. Are there any obvious differences between dead FP and dead CKP? Some notes from the other day, when things really fell apart include:
- Car was running hard all day and seemed to work well
- When things started to act up they got worse pretty fast, going from a shutoff every 5 minutes or so to random shutoffs every 30 seconds. Most of the time, though, the car would restart on demand into the low hunting idle.
- Opening the throttle while the car was in low hunting idle mode would usually cause the car to die
- Power seemed good when the car was not in low hunting idle mode
- The fuel gauge was dead the whole time, just the second time the car has done it
- I want to be careful saying that it is heat related, but every time the car has done it has been at low speed or after being parked and is still very warm.
Some of those characteristics seem more fuel delivery related (gauge being dead, engine stall when giving it throttle in low hunting idle mode), and the others seem more sensor related (flipping between "good car", "bad car" rapidly, no code engine stalls, rapid degradation). I would really appreciate some opinions. That said, the car is a late 2003 so I don't really want it to be fuel delivery. Please consider that in answers
The car first did it about 4 months ago, literally as I finished driving across the country. Stall, failed restart, restart into a hunting idle for 10 seconds, resume normal idle and behaviour. No CEL.
Second case was about a week ago, with one instance of a hunting idle on startup, no stall. Later in that day I had the gas gauge stick to low fuel until I filled up. (It stuck to "low" when the tank was about at 1/4)
Third and terminal case was yesterday. Driving home from a lapping day the car went through increasingly frequent and consistent shutoff/restart cycles. I was barely able to limp home as the ratio of "good" to "bad" got progressively worse. At the end of the drive I was going one residential block at a time and dashing across intersections so that I wouldn't get stuck in them. The "bad" mode got consistent as I mentioned - If the throttle was open and the drivetrain was engaged the motor would lose all power. If the motor was not clutched to the drivetrain it would drop to a low hunting 500 rpm idle. Giving it throttle would kill it. After dying it would fail to restart once or twice and then eventually start working. Once I learned how to keep the motor running (do nothing, just wait for the bad spell to pass), it would eventually resume a normal idle and be able to move the car. This repeated in ever shorter cycles. Much earlier in this drive the fuel gauge had stuck to "low" at nearly a full tank.
Currently the car has one code set, P1431 H, C and the fuel gauge still reads low. There are no other codes in history and the battery has not been unplugged for some time. The car blew a very clean emissions test back in September.
Corvette forum literature review seems to point down two roads - fuel pump or crank position sensor. I don't have any of the kit necessary to diagnose it, so I was looking for some thoughts before I buy anything.
I have two questions for the forum:
1. Anything else I should consider?
2. Are there any obvious differences between dead FP and dead CKP? Some notes from the other day, when things really fell apart include:
- Car was running hard all day and seemed to work well
- When things started to act up they got worse pretty fast, going from a shutoff every 5 minutes or so to random shutoffs every 30 seconds. Most of the time, though, the car would restart on demand into the low hunting idle.
- Opening the throttle while the car was in low hunting idle mode would usually cause the car to die
- Power seemed good when the car was not in low hunting idle mode
- The fuel gauge was dead the whole time, just the second time the car has done it
- I want to be careful saying that it is heat related, but every time the car has done it has been at low speed or after being parked and is still very warm.
Some of those characteristics seem more fuel delivery related (gauge being dead, engine stall when giving it throttle in low hunting idle mode), and the others seem more sensor related (flipping between "good car", "bad car" rapidly, no code engine stalls, rapid degradation). I would really appreciate some opinions. That said, the car is a late 2003 so I don't really want it to be fuel delivery. Please consider that in answers
Last edited by wtb-z; 01-27-2014 at 01:56 AM.
01-27-2014, 01:28 PM
#2
Pro
Thread Starter
For some extra context, the day the car really broke on Saturday, I filled the car all the way up just after I left the track. ~60 miles later the gauge pegged to "Empty" and ~100 miles later the car started shutting off.
01-27-2014, 01:59 PM
#3
A bottle of techron generally solves the fuel guage issue. As for the shutting off, along with checking the fuel pressure you might also clean your MAF