I have a 79 TA LT1 that broke a timing chain. It was repaired at the shop where my son works. New Distributor, new crank position sensor. new ignition module, flashed the ECM and rebulit the heads. Now, it has error codes showing random misfires, ignition voltage too high, and improper timing pulses. it runs, but very rough. We can't get rid of these and the local dealer wanted to replace all the parts we put on before he would even look at it. Because we had to replace so much at once, it is hard to find the problem. Anybody got an idea? it has been 2 months and we are stuck!
Thanks for any help
Texcamaro

 

Start with the misfires. Pull the plugs for the cylinders showing misfires and swap another plug wire and replace the plug. See if the plug shows actual signs of misfiring. See if the new plug and swapped out plug wire now are no longer misfiring.

For those cylinders that just won't stop misfiring AFTER you have tried swapping a different wire from a good cylinder and replacing the plug do the following:

Use an inductive timing light to see if the flash pattern is different for the misfiring cylinder than it is for a non misfiring cylinder.

Put #1 at TDC and pull off the cap from the distributor. Be sure the rotor is pointing near the 6 oclock position where the number one contact is in the cap. While you're there, check the cap and rotor for signs of problems.

 

What were the EXACT codes, particularly the one for "improper timing pulses"?