Drag Racing Tech - Please help. No tach after new motor install

I have a 99 trans am. I pulled the 383 out for a 402 and also did some weight reduction and everything else. I busted her off yesterday and I didn't have a tach. All other gauges will read but the tach doesn't. Soon as I crank it up it will peg out and then go to barely above zero then I cut the car off and it falls all the way down Factory PCM and everything. I'm just stumped. I thought it could be a ground issue. But where. Please. Any help would be appreciated

did you change from a 58x to 24x reluctor (or vice versa) without an adapter?

I'm almost certain I did. I didn't think of that. So what do I do now

I had a similar problem. I figured it was a tune issue, so I brought it to the shop that was doing the tune for me and he said it was a crossed wire in the cam sensor extension, and that it happened alot. They just switched the wires in the extension and the tach started working again. It didnt make any sense to me, but it worked.

Is your cam sensor hook up?
I had the same problem afew back and the cam sensor plugs were not hook together.
The 2 plugs on the pass side of the intake.

Make sure all grounds are hook up on the drivers side head. I think there are 3 of them.

I had a similar problem. I figured it was a tune issue, so I brought it to the shop that was doing the tune for me and he said it was a crossed wire in the cam sensor extension, and that it happened alot. They just switched the wires in the extension and the tach started working again. It didnt make any sense to me, but it worked.

This! I had the same issue when I first fired up my 416.

All the grounds on the drivers side head are hooked up and I'm going to check the cam sensor wires where I ha to extend them At first the car ran fine just acted like it needed a tune now it will hardly crank and sounds like it is poping through the exhaust as the motor is rolling over and eventually it will crank when I hold my foot to the floor. The tune in the car is for 42 lb injectors and now it has 60 lb injectors so I may have killed some plugs but that wouldn't explain why it's poping in the exhaust

Just checked wires on cam sensor and they are correct so I'm assuming it's going to be the reluctor wheel issue y'all was talking about. I know lingenfelter makes one does anyone else? Kind of on a budget but the car gets what the car needs lol.

Don't try to crank it anymore, mine backfire and blew the back out of a Fast intake.
See which reluctor wheel you have.

How do I find out which wheel it is?

Ok I have just found out that I have a 24 tooth wheel which is correct for my car. Now what. Please guys I got to get this figured out before Saturday that's when I'm getting it tuned. Does any one have a run down of everything that has to be in order for the tach to operate correctly It was working fine with the old motor now it's not

I take it you have an ls2 now. I am not sure if you are aware but two of the wires have the positions switched from an ls1 compared to an ls2 for the cam sensor.


Also check to see if you are throwing any codes

I take it you have an ls2 now. I am not sure if you are aware but two of the wires have the positions switched from an ls1 compared to an ls2 for the cam sensor.


Also check to see if you are throwing any codes

The cam sensor has 3 wires
Red IGN
Pink/Black REF LO
Brown/White CMP SENS SIG IN

I don't know switch wires to swap, but I have heard some harness extentions
are wire backwards.
I would swap the Pink/White and Brown/White around.
The Red wire is telling me that's where the cam sensor gets it's hot from.
Probably 12 volts from the PCM.

All I remember is the two outter terminals are switched from ls1 - ls2

The 2 outside wires are the Red and Brown/White.

All I remember is the two outter terminals are switched from ls1 - ls2

You are 100pecent correct Swap the two outer wires on the cam sensor and that bitch will crank up and run like a champ lol. Thanks alot guys.

Great!

Glad to help. Yeah I got burned by the same thing when I installed my 385 earlier this year