LS2 engine swap wont start - help

[Paul Buxe]

So i have finished the LS2 engine swap after 8 months of work I can't gt any spark and the engine wnt start. I have an LS2 motor out of a ’06 Corvette with a 58 tooth reluctor wheel . I have a Holley 750 carb set up so I had to add the 58 tooth MSD carb ignition system to make the switch over from FI. Anyway, the car won’t start. I checked and am getting 12 volts to the MSD box, an getting 12 volts to the coil packs (which I got used on the forum, could be an issue), but I get no spark at the plugs. So any ideas? What resistance should I read on the crank sensor, the cam sensor and the coil packs? I’m thinking that is the only thing that could go wrong. The crank sensor is new from GM, the cam sensor came with the engine. I am told the jumper cable to the cam sensor needs to be deleted for the MSD box to work right, because it seems to reverse the wires to and from the connector and have tried to start the car with and without the jumper wire, but didn’t make any difference.
Any ideas?

[eric1h]

Che k the crank sensor, cools also be a bas crank sensor.... I've seen that happen on used motors... If it were the. Cam sensor it would at least sputter and try to start, but if the crank sensor is bad the car won't even get any spark.... Do you have a timing pill in the msd? It won't start unless it has one in for the first start.....

[eric1h]

Also try hooking up the serial cable to the msd box and check to see what it sees it should at least show a signal from the various sensors... And it will confirm the msd is powered on and working

[Panoz26]

Paul - what MSD are you using? Mine was plug in play, meaning, I did not have to delete anything... I find that odd. 6012 unit.

[eric1h]

Originally Posted by Panoz26

Paul - what MSD are you using? Mine was plug in play, meaning, I did not have to delete anything... I find that odd. 6012 unit.

Yeah what jumper?

Should be 5 wires...

Power, ground, pink power, cam, and crank sensors......
And make sure you have chip in.

[Paul Buxe]

The jumper I'm talking about the the jumper cable that goes from down under the crank chaft pulley in a black curved bracket up the the cam sensor. If you look at the wires, they reverse as they make the run. A friend that put an LS2 in his Backdraft said he had to by pass that jumper to get his engine to run. But I tried it both ways and no spark.

[Panoz26]

Paul, double check with what Eric mentioned on the "chip" or "pill" -- ensure you have one in the MSD unit. It's been known to fool a few folks.

On the "jumper" -- in my LS3 with the MSD 6012, I did not have to do anything like that.

[Paul Buxe]

Thanks guys.
1) yes I have a pill installed
2) the crank sensor is new from GM so I'm thinking it should be ok does anybody know a restance check?
3) the cam sensor came with the motor, so it could be bad, does anybody know a restance check?
4) I need to bring my lap top home tomorrow and do the check out you suggest, good idea.
5) I'm getting 12 volts to the coils but it looks like no triger input, could be sensors.
Thanks guys

[eric1h]

Any luck?

One thing that stuck in my mind.... What crank sensor do you have? I remember reading about 2 different types of sensors... Grey and black, and you needed the correct one for the msd to work properly, I can't remember details but it's worth a little research possibly.

[Cobrafang]

Originally Posted by Paul Buxe

Thanks guys.
1) yes I have a pill installed
2) the crank sensor is new from GM so I'm thinking it should be ok does anybody know a restance check?
3) the cam sensor came with the motor, so it could be bad, does anybody know a restance check?
4) I need to bring my lap top home tomorrow and do the check out you suggest, good idea.
5) I'm getting 12 volts to the coils but it looks like no triger input, could be sensors.
Thanks guys

Hit CTRL-ALT-DELETE and install a stroked SBF motor.

[Cobra4B]

Will it turn over? Did you open up the front of the motor to ensure it doesn't have a broken timing chain?

[Paul Buxe]

Thanks for the ideas guys, except for the stroker FMC thought, I've had this thought a couple of times, but I'm where I am.
Yes I checked both sensors and have the correct sensor for the LS2.
Yes, I had the engine apart when installing the new cam shaft. It turns over and cranks fine on the starter, just no spark.
Tonight I will connect the lap top and see if it gives me any codes, like a dead sensor or a fried MSD.
Keep the fath.

[Paul Buxe]

The problem is that I am not getting any spark at any of the cylinders.
To trouble shoot, I have replaced both the cam and crank sensors (gray).
I am getting 12 volts to the MSD box.
I am getting 12 volts to the coils.
I am getting 5 volts to both sensors.
I have the step retard unhooked.
I have the MAP unhooked.
When I crank the engine, with or without the spark plugs, I do not get a tachometer reading on the lap top. Engine is turning over at a good speed.
I also get a “no crank signal” on the lap top. This is why I replaced both sensors.
I am getting ~ 4.5 volts return from the cam sensor. (using a multi meter, so don’t know how good that volt value really is) back to the box.
I am getting ~1.3 volts return from the crank sensor. (using a multi meter, so don’t know how good that volt value really is) back to the box.
I am only getting ~0.05 volts to the coil packs to fire the coil from the box (using a multi meter, so don’t know how good that volt value really is)
So, I’m stumped. The box is new, but can it be bad?
What else would you suggest?

[Panoz26]

Paul, I have not seen this addressed, so, I'll ask:

Have you checked to make sure the coilpacks are on the right way? This may sound silly, but if #1 is on #7, it could cause the car to not start.

Devin

[eric1h]

Honestly, best bet would be to call msd support!