All

Need serious HELP on this one please?

I have had 3 almost identical failures with my charging system since I installed, from deWitts, “spal” electric fans in August past.

Incident 1 occurred on my first track day after about 30 minutes driving when the car would not start and the charging system read 2.5V. It did start with jump leads but ran pooring and limped about 1 mile before I had to call for the toe truck. We checked the alternator, it was shot and we bought a new stock one.

Incident 2 occurred on my second tracl day after about 2 hours. The car would not start prior to a run. It would also NOT start with jumper leads but would start with a push. The charging system read 12.5v. This time we checked the starter motor but was OK.

I replaced the alternator this time with a 270Amp super duper. Typically this was charging at 14.5v about 1 volt higher than the stock one.

Incident 3. On my way to the track again, this morning, from home, the starter did not fire at 1st push of the button, but did fire at the second.
I was nervous of the charging system so I kept the display on the charge and it sat steady around 14.5V the whole way to the track, say 45 minutes.

I stopped for gas and again on attempting to start, it was the second push before it caught. I drove 30 feet and stopped again for coffee. The car would not start this time. On pushing the green button, the fans started etc so there was charge at the battery. With jumper leads it again would not start. With a push it did start, but the charging was displaying only 11.2V

I elected not to go to the track and instead returned home. I kept the display on charging and watched as it dropped 11.2, 11.1, 11.0 etc all the way to 10.6. Various warning signs came on “service charging system”, “service active handling”, “service ABS”. All these had also come on after the first incident

After 40 mins, the display suddenly shot up to 14.4v, stayed there for about 3 mins, then dropped to 13.5v , then back to 14.5

I stopped the car at a reading of 14.5 and of course it would not start

The only change to the electrics from stock are the twin fans. They use 45amps total which is a drop in the ocean for a 270 amp alternator.

What is going on? We are baffled. What checks do I need to do? This car is heavily modded and there is no way the dealer will ever want to see it

Thanks

John

 

have you checked for shorts in the ignition system? how about a check of hte battery itself? how does it rate? from what I've read here, the alt. being shot indicates it's either bad itself from other reasons, or it's been working overtime to keep the system going (as in, a bad battery)

 

I just went through a similar situation with my vette. The problem was a loose connnection at the starter, which means the alternator and battery cable were not making a good connection.

 

i dont see why the dealer wouldn't touch it. its just the electrical system. unless that is modded, but i doubt it.

could be anything from, a fuseable link, to a shorted diode.

have you tried a different PCM?

also, maybe try runing a bigger gauge wire from the alternator to the battery.
..

let the car sit in your driveway, have it idle, does it eventually start dropping voltage? if it does, see if popping the hood, then putting a big cfm fan on the alternator and see if that help.

-carl

 

try a new battery first

 

Intermittent ground problem?
Wiring harness for aftermarket fan?
Or bad battery.?

 

When I took my alternator to a rebuilder after it died (during a track event, btw), he said alternators don't live very long when subjected to high speeds. i.e. upwards of 5K engine rpm.

Just sayin.

 

Concencous opinion from here and the z06 board would suggest that the connection at the starter solenion is where the problem rests

I will investigate and report back

thanks guys

John