baggett3_27

have you checked for leaking injectors and coil pack wiring harnesses installed correctly?

2 Stroke Racer

iTrader: (11)

I know you changed the crank sensor, but check wires going to the sensor.
If they got too close to the header they could have melted, even inside the wire loom.

mypoorLS1

iTrader: (4)

I think you've already been given the correct answer. You have a bank of coils backward. I've done it, sounded the same. On one head, the big plug that goes to your coils. Lets say it cylinders 1,3,5,7. You have it hooked up 7,5,3,1. So, leave the big plug alone, unplug the coil packs, plug the one that was going to cyl. 7 into the no, 1 coil, the one that was plugged into cyl. 5 into no.3 coil, the one that was plugged into the one that was on cyl. 3 into number 5 and the plug that was on no 1 into number 7. Don't quote me exactly. . . because it could be 2,4,6,8. Quit throwing money at it until you have tried everything else.

tylermoore

Took it to the shop right down the road, they did a crank relearn and made sure all the sensors were good and it runs alot better know. Problem i see now is it falls on its face at about 3000 rpms. Im suspecting valve float/worn out springs. Everything was replaced in my motor but the upper valve train-push rods/ rockers and springs. I think the springs are tired lol. If anyone can confirm my prognosis it would be appreciated.

THanks for the help so far guys

tylermoore

Yes i double checked all the coils the other day and made sure. I totally forgot about getting a relearn one. I should have known it would be something simple. I put about 55 miles on it today with no problems but the possible valve float thing.

waterbug1999

iTrader: (3)

I did that as well.. with one side flipped it would start and stay running but backfire. With both flipped it would backfire but only while cranking and not start.

RezinTexas

this has happened to me also, with the same symptoms as the OP.