Finally started have electrical gremlins
07-20-2013, 01:12 PM
#1
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Finally started have electrical gremlins Finally got my Lq9, dual plane, QFSS830 swap into my 240sx running this weekend. Car started right up after priming it and sounds damn good. Complete rebuild everything new but block. Took it for a quick spin around the block and while checking the MSD output on the laptop I noticed that the battery voltage was low and slowly dropping.
Electrical System:
Optima Redtop located in trunk 2ga wire from battery to New Starter (20ish feet) 4ga from starter to fuse box, 8 or 10 from starter to alternator.
New CTS-V Alternator Part number: 25766345 from GMPP FEAD.
Battery Grounded to chassis at the trunk 2ga
Passenger head grounded to frame rail upfront via welded stud 4ga
1. For first start up MSD box showed 12.5 volts and battery was freshly recharged.
2. about 15 mins lapsed from first fire to quick .8 mile trip around neighborhood.
3. Voltage showed 9-10 once back in driveway
So I shut it down and started some digging. For wiring in the alternator I followed this thread:
https://ls1tech.com/forums/conversio...or-wiring.html
Where it was discussed that the alternator would function at 13.8 volts as a default if the reisitor/light was missing. So i didnt have the L field on the alty hooked to anything. Also recharged the battery overnight and noticed that the VM showed 12.5 at the battery but down to 8 at the starter. Pulled the wire from the fuse box and still showed about 8 at the starter. Then my VM **** the bed so had to switch to noid light!.
Today I did the following:
1. Recharged battery
2. Wired in dummy light lead to L field without resistor. Cant remember if there is an actual bulb in the dash or I pulled it.
3. Fired right back up and still no charging.
4. Wired in fan (taurus) and once it kicked in the car had to be jumped to start.
5. MSD still showed about 10-11 while running
My thoughts are: I need a new VM, the resistor to L field wire on alty, maybe larger cable from batt to starter. However I wanted to get some feedback on the overall setup and thoughts. Also because the MSD was only seeing about 10-11 my choke would not function so the car stayed in fast idle mode running rich between 10.5- 11.5 on the wideband but could never be dialed in due to choke not functioning. Also noticed that if I unplugged the + lead to the choke the noid light would lightly light up but one plugged in it read nothing.
Everything else in the car functions, MSD, fuel pump, gauges, stereo, fan, lights etc. But I havent checked the voltage.
Electrical System:
Optima Redtop located in trunk 2ga wire from battery to New Starter (20ish feet) 4ga from starter to fuse box, 8 or 10 from starter to alternator.
New CTS-V Alternator Part number: 25766345 from GMPP FEAD.
Battery Grounded to chassis at the trunk 2ga
Passenger head grounded to frame rail upfront via welded stud 4ga
1. For first start up MSD box showed 12.5 volts and battery was freshly recharged.
2. about 15 mins lapsed from first fire to quick .8 mile trip around neighborhood.
3. Voltage showed 9-10 once back in driveway
So I shut it down and started some digging. For wiring in the alternator I followed this thread:
https://ls1tech.com/forums/conversio...or-wiring.html
Where it was discussed that the alternator would function at 13.8 volts as a default if the reisitor/light was missing. So i didnt have the L field on the alty hooked to anything. Also recharged the battery overnight and noticed that the VM showed 12.5 at the battery but down to 8 at the starter. Pulled the wire from the fuse box and still showed about 8 at the starter. Then my VM **** the bed so had to switch to noid light!.
Today I did the following:
1. Recharged battery
2. Wired in dummy light lead to L field without resistor. Cant remember if there is an actual bulb in the dash or I pulled it.
3. Fired right back up and still no charging.
4. Wired in fan (taurus) and once it kicked in the car had to be jumped to start.
5. MSD still showed about 10-11 while running
My thoughts are: I need a new VM, the resistor to L field wire on alty, maybe larger cable from batt to starter. However I wanted to get some feedback on the overall setup and thoughts. Also because the MSD was only seeing about 10-11 my choke would not function so the car stayed in fast idle mode running rich between 10.5- 11.5 on the wideband but could never be dialed in due to choke not functioning. Also noticed that if I unplugged the + lead to the choke the noid light would lightly light up but one plugged in it read nothing.
Everything else in the car functions, MSD, fuel pump, gauges, stereo, fan, lights etc. But I havent checked the voltage.
07-21-2013, 08:45 AM
#2
If your alternator isn't putting out 14+ volts when running than there is no point in chasing voltages around. Get you alternator sorted out and working before you do anything else.
The last thing you need is a larger cable going from the battery positive to the starter. What you do really need is an equal sized cable going from the battery negative to the block.
Prior to the 70's car manufactures only made cars to last for 8-10 years tops. It was called planned obsolescence. Delete all the ground wires, save $10 on the price of the car, then when all the chassis ground start to corrode causing intermittent electrical problems the owners will trade in the old piece of junk on a new car. A win-win in their books.
If you notice on modern cars all the EFI stuff has dedicated ground wires. Do the same thing and don't rely on rusty old sheet metal to carry current.
Also I would hook the battery negative to the block and not the head. LS motors are weird, if you ever take an ohm meter to a valve cover it is an open circuit to the block. I think the head is OK but to be safe I hooked the battery negative straight to the block.
The last thing you need is a larger cable going from the battery positive to the starter. What you do really need is an equal sized cable going from the battery negative to the block.
Prior to the 70's car manufactures only made cars to last for 8-10 years tops. It was called planned obsolescence. Delete all the ground wires, save $10 on the price of the car, then when all the chassis ground start to corrode causing intermittent electrical problems the owners will trade in the old piece of junk on a new car. A win-win in their books.
If you notice on modern cars all the EFI stuff has dedicated ground wires. Do the same thing and don't rely on rusty old sheet metal to carry current.
Also I would hook the battery negative to the block and not the head. LS motors are weird, if you ever take an ohm meter to a valve cover it is an open circuit to the block. I think the head is OK but to be safe I hooked the battery negative straight to the block.
07-25-2013, 06:14 AM
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Just wanted to update.
Added the resistor to the L field of the alternator and it was charging at 13.5 at idle however once I started driving it it would drop down to 12. Broke the engine in the motoman way for about 25 miles and it felt great but it was running pig rich with the af gauge pegged at 10 anytime throttle was given.
Parked it and started to look into fuel issues and noticed that at 6.5 psi according to my gauge that the fuel level in the quickfuel was way above the sight glasses. Attempted to adjust the fuel level on the carb and the could not reduce the fuel level at all and started to **** gas everywhere. Floats would move but the fuel level wouldn't. So I m thinking the gauge may be a little off and fuel pressure is too high.
I fixed the battery voltage problem this week. Redid the ground from the battery to chassis in the trunk. Removed the 4ga from the head and replaced with a 2ga. Then added a 4ga from the back of the bkock to the firewall. Now voltage shows over 12v at the fuse box, battery, alternator with the car off where before it showed 7-8. Going to drain the carb and reset the Mallory fpr from scratch and slowly adjust fuel pressure until fuel is at the right level in the sight glass.
But man this beast was awesome during the break in run.
Added the resistor to the L field of the alternator and it was charging at 13.5 at idle however once I started driving it it would drop down to 12. Broke the engine in the motoman way for about 25 miles and it felt great but it was running pig rich with the af gauge pegged at 10 anytime throttle was given.
Parked it and started to look into fuel issues and noticed that at 6.5 psi according to my gauge that the fuel level in the quickfuel was way above the sight glasses. Attempted to adjust the fuel level on the carb and the could not reduce the fuel level at all and started to **** gas everywhere. Floats would move but the fuel level wouldn't. So I m thinking the gauge may be a little off and fuel pressure is too high.
I fixed the battery voltage problem this week. Redid the ground from the battery to chassis in the trunk. Removed the 4ga from the head and replaced with a 2ga. Then added a 4ga from the back of the bkock to the firewall. Now voltage shows over 12v at the fuse box, battery, alternator with the car off where before it showed 7-8. Going to drain the carb and reset the Mallory fpr from scratch and slowly adjust fuel pressure until fuel is at the right level in the sight glass.
But man this beast was awesome during the break in run.
