4.0 motor pinging under load

[waynehartwig]

I checked the timing and it is usually 12 degreees at idle with an occasional drop to 10. The advance at high speed and under a load with the RPMs up is around 35 degrees. I put a piece of tape with half inch marks on the dampner to estimate the high speed timing so I could be a bit off. I'll look at TDC on the #1 cylinder. It doesn't have a vacuum or a mechanical advance. The advance is done by the computer. I wonder what sensors it checks to know how far to advance it ?
Dave

Probably just goes off of engine RPM....

Can you change the timing to get rid of the ping? Not that it's a solution, but out of curiousty.... I'd still check the harmonic balancer, though. Make sure it shows TDC when in fact it is TDC on #1.

 

[DaveB]

Probably just goes off of engine RPM....

Can you change the timing to get rid of the ping? Not that it's a solution, but out of curiousty.... I'd still check the harmonic balancer, though. Make sure it shows TDC when in fact it is TDC on #1.

The timing is set with a pin on the block and a notch on the distributor. I could try putting it off one tooth on the distributor or off of the notch but I would have to see how far off it would be if I did that. I checked the TDC mark and it appears to be correct.

 

[waynehartwig]

The timing is set with a pin on the block and a notch on the distributor. I could try putting it off one tooth on the distributor or off of the notch but I would have to see how far off it would be if I did that. I checked the TDC mark and it appears to be correct.

I wouldn't do it unless there is a possibility that it is off in the first place.

Does the EGR function properly? If you put a vacuum on it, will it all but kill the motor? I know you just had a smog done on it, but still....

 

[DaveB]

I wouldn't do it unless there is a possibility that it is off in the first place.

Does the EGR function properly? If you put a vacuum on it, will it all but kill the motor? I know you just had a smog done on it, but still....

It doesn't have an EGR valve...