Help with intermittant no start
07-15-2007, 06:06 PM
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Help with intermittant no start I am running a 1999 C5 with a 420ci L92 based engine. Stock PCM using EFILive for tuning. I have run into a problem where occasionally at key on, the DIC displays a bunch of messages including REDUCED POWER, LOW FUEL, SERVICE ACTIVE HANDLING etc.. The car cranks, but the ECU is not firing the injectors and it will not start. The tell tale sign I am having this problem is that the Fuel Gauge reads empty no matter how much fuel is in the car.
My solution is to disconnect the battery for about 20 seconds and usually everything returns to normal. Sometimes the ECU needs a longer nap like 10 minutes.
It has only happened a few times in the past, and it tends to run in cycles, like it will happen a bunch all together and then be gone. No other changes. Yesterday it left me stranded on the grid with a no start for a race in which I was in gridded in the front row. I never got it running to make the race. Later it started right up and I drove it into the trailer.
I can't afford another DNS in a race so I need to figure it out. I would think battery voltage, but it has happened on the dyno before and I always keep the battery hooked to the charger so I don't lose power when I am sitting in the car tuning. I know the battery was fully charged.
Temperature also seems unrelated, because it happened at Thunderhill on a cool weekend and this weekend it happened while the car was still cool sitting on grid.
Any thoughts?
thanks,
Aaron Pfadt
My solution is to disconnect the battery for about 20 seconds and usually everything returns to normal. Sometimes the ECU needs a longer nap like 10 minutes.
It has only happened a few times in the past, and it tends to run in cycles, like it will happen a bunch all together and then be gone. No other changes. Yesterday it left me stranded on the grid with a no start for a race in which I was in gridded in the front row. I never got it running to make the race. Later it started right up and I drove it into the trailer.
I can't afford another DNS in a race so I need to figure it out. I would think battery voltage, but it has happened on the dyno before and I always keep the battery hooked to the charger so I don't lose power when I am sitting in the car tuning. I know the battery was fully charged.
Temperature also seems unrelated, because it happened at Thunderhill on a cool weekend and this weekend it happened while the car was still cool sitting on grid.
Any thoughts?
thanks,
Aaron Pfadt
07-15-2007, 10:33 PM
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Aaron,
I believe your key tumbler VATS interogation ckt is going south. Find the BCM, and the wiring from the tumbler. Put the key in, read the resistance; turn the key, if it goes open, that is your problem. Goto your local Radioshack, etc. and build up the corresponding resistors and cut the wire to the BCM and install it in line to ground.
Simply turning off VATS is not going to cure this. Fix this now before your intermittent problem strands you somewhere.
I believe your key tumbler VATS interogation ckt is going south. Find the BCM, and the wiring from the tumbler. Put the key in, read the resistance; turn the key, if it goes open, that is your problem. Goto your local Radioshack, etc. and build up the corresponding resistors and cut the wire to the BCM and install it in line to ground.
Simply turning off VATS is not going to cure this. Fix this now before your intermittent problem strands you somewhere.
