tach jumping and knocking
 

k i have a 88 turbo 2 bridge ported with a e6k and for some reason is just started to knock real bad with the tach jumping at the same time and it jumps a good 1500rpm but i have shielded the trigger harness and grounded it and added a ground strap from battery to the block and checked timing many times and the map also every thing is fine with the map cause for some reason i thought we had fixed it and we were able to tune the car but the next day it stared again i can boost about 2 times with no knock or tach jumping but on the third pull it will start to mess up its like something is heating up i replaced the trailing coil but with another used but the coil gets pretty hot way to hot to touch but i can touch the leading coil all i want and its no where near that hot if any body has any ideas please let me know this is getting very old

o and it only happens when i hit boost about 7lb about 4200 rpms

any ideas

Sounds like a trigger issue. What is the data stream showing for RPM reading when this happens?

its rock solid it happens to quick the haltech doesn't show any thing

I can't figure this one out. I shielded the trigger harness and grounded the shield to the engine. Also had ground wiring added from the battery to the engine. Still randomly does it. I have no idea why.

B

Eric, I wasn't aware the trailing coil was getting real hot. Idea: grounding from battery to chassis. Are you still using the original ground? It might be a good idea to do a large gauge lead from the Battery -12V to chassis ground. The reason why I bring that up is in case there's a ground problem on the chassis since that ignitor/coil is getting really hot. It's directly grounded to the chassis. May also want to have a look at whether or not the three 10mm nuts holding the trailing ignitor are on securely and tight.

B