Help, some sort of voltage issue... engine related.

[InfiniteGSX]

Ok, A little story. My car dyno'ed at 456whp and as I left the dyno I was t boned. So I picked up a new shell for a grand, in mint condition. It needed a new harness, So I transplanted my motor, trans, tc, wheels, suspension, and front car harness into the new car. I started it up and it was chugging. Then I found a hole in the coupler on the intake.... so I figured that was it. Fixed it. Problem is still there. Also noticed now, when I hit the brake, it almost kills the power completely. Voltage is like 12.5v not running on a perfect battery and dropps down to like 8v when I hit the brakes. I start it up and I can almost kill car by touching the brakes or trying to roll down the windows. And its like running on 1 cylinder, or 2.

When I pulled the motor, it was running fine and flawless. And actually very reliable. I know it has to be something voltage related but I cannot find anything wrong. All fuses are good. Relays should be good because they came from the old car.

I flipped over the CAS like 50k times thinking something was off.... but that isn't it. I don't know what else to do, except pull the harness off and reinstall it.

 

[scott90gsx420]

Is the alternator all hooked up right? As in all the wires are there and hooked up also? IS it the same one that was in the old car? Id say its related to that. What are the volts while the car is running before you push the brakes? and what is it when you push it?

 

[InfiniteGSX]

I can't get actual voltage because I don't have anyone to help me press the brake and what not. But alternator only connects one way and its connected. Same alternator, everything from the previous shell. its all the same. just moved a motor and harness and everything that makes a car run and move, to a new body.

But without the car running, if I open the door and press the brake, the lights almost turn all the way off, like the battery is dead but its not. the lights are bright until something else turns on. Like emergency lights, car running dims the lights down a lot.

Even if the alternator wasn't connected, the car would still run flawless till the battery became low... but the battery is not low, battery is even on a charger that turns on when it gets below a specific area, and turns off when its charged. because I've been using the radio.

Ok, I found the voltage drop issue. dunno how it caused an issue. I pulled the main ground that goes to the transmission and sanded it down and boltted it back up and the voltage drop is not there anymore. Car runs better... But still missing severely.

I don't know how that caused a power drop.... I had the lights working without the motor even in the damn car. And it never did that.

Ok I don't know. I'm prob just going to get rid of her. Really upsetting a wreck has to ruin everything for me.

It just spits. And won't rev past 5k. All this came out of the other shell running flawless. Not one single thing is different from when it was in the other car. Just went through each coil pack. Cleaned them up. Installed new plugs to replace the plugs that have maybe 50 miles on them. I switched injection wires around a few ways but I had them labled and it did nothing.

I'm tired!

 

[scott90gsx420]

Well have you tested the coil pack. The voltage drop could have fried them internally. I think that my bad alternator caused that to happen to my coil and i now have a weird miss. Although mine is very small and doesn't have any drivability issues.

 

[InfiniteGSX]

I tested them just now. They are within spec to be considered in good condition, considering I have a shitty multimeter. I also tested grounds all over the block.... even the shadiest area that I would almost bet money wont be grounded (the spark plug cover on the valve cover area which was powdercoated) is getting a perfect ground signal.

I just made sure the CAS is aligned to TDC. From the wire diagrams of the COP how to's, my cop is wired in right. Also motor is exactly aligned right at TDC.

Now it wont start. But "when" it does, I can rev it above 0 rpm and the battery light goes off and the alternator puts out a perfect 13.52v and stays there.

Someone mentioned a ground for the ECU... but only small grounds like that I can fine is right off of the ECU Plugs which bolt up down there in the center console area. That I just disconnected and reconnected and made sure it was getting a perfect ground. Then there's one on the firewall, I grounded that before t he engine bay was detailed.... I might take it off and move it to another location or test it here in a little bit to make sure its grounded.... there's one that connects to the body right by the front of the driver fender. Thats grounded and tested. The engine has a main large ground that bolts to the firewall/battery ground, and transmission right by the starter. That I unbolted, sanded down the powdercoating and reconnected it, that fixed the power drop issue. Usually stock the intake manifold is grounded... but I tested it and its getting a perfect ground, Plus nothing is bolted to the intake manifold that requires a ground.

I wanna find someone with a stock coil pack I can use... pull the spark plugs and test them, even tho they are brand new, well two have 0 miles, other two have like 50 miles on them. I made sure the cop's were fireing... they are... they are sending a pretty big bolt out of them... I let them shock the fender... and they were all fireing just right.

Ok, I just tried different gas with a portable fuel tank with an in tank fuel pump , nothing! I know the coil packs are working... but doesn't seem like they are fireing the spark plugs.... maybe? head is perfectly grounded.... so that can't be the issue. Next I guess is to take the plugs out and test the plugs with the coil packs.

 

[InfiniteGSX]

Ok problem was fixed. It was the cop. Got a stock coil pack and some shit wires and boom it runs. But now its acting up again. I think the stock coil packs are dying to. So something is killing them. Power transistor...?

 

[scott90gsx420]

It could be. Try swapping it out if you can.. It sounds like youve got a bad ground somewhere try looking around inside and outside the car and clean all the grounds. Also if the wires around the ECU are frayed or anything they could be or already have fried the ECU.. Pull the ECU out and look for any burns or leaking caps.

 

[InfiniteGSX]

I've already gone through every ground possible. If the coil pack didn't work when it did, I was going to sell the car. I had 9 offers for 5k in its current condition and I was at the end of my limits with it. Just think of the most outrageous thing that could happen, and it happened. I have perfect ground. What I think it might be is the Power Transistor, but I'm not sure. Thats next in line after new wires.

 

[InfiniteGSX]

Ok. Confused! WTF! I fixed it. With stock coil pack and wires. It started right up, Ran great. For a couple days. I didn't drive it around much, but did drive it around the block. Then it started doing it again. Thought it fried the new coil pack.... Well I just got another confirmed working coil pack and good wires and it took a lot to get it to start and when it did, it was hardly running.

It now has new spark wires, new coil pack, new wires. And I have confirmed timing belt is timed right, CAS is right. and wires are in the right order.

I don't know what else to do.

Proof of it running!
<iframe width="425" height="349" src="http://www.youtube.com/embed/e740CPY14cY" frameborder="0" allowfullscreen></iframe>

 

[luv2rallye]

You may have a heat related failure like the power transistors. Test them here first without and then with a hair dryer blowing on them to heat them up good: http://www.dsmtuners.com/forums/articles-electrical-wiring/229419-how-test-power-transistors.html.

Also do you have the PT bolted down to the head on their special bracket? They use the ground surface under them to transfer heat and allow better current flow than thru their ground wire.

 

[InfiniteGSX]

No. I haven't had them bolted to the Motor in years. I relocated it from the Intake Manifold to under the Intake Against the firewall. Much cooler spot anyway. And I never had issues until I moved the motor from the black car to the silver car... New thread...

http://www.dsmtuners.com/forums/maintenance-repairs/409887-multiple-dead-coil-packs.html

but yes, I do believe its the Power Transistor now. I don't have a way to test it right now but I'm working on it. I think I just wanna replace the power transistor and get another coil pack. If it kills another coil pack, then I don't know.