cylinders 3 & 5 with weak spark with FAST

[ttypewhite]

I have the classic FAST bank to bank in my car. I started the car and it feels like it is running on 4 cylinders. I pulled the injector harness off those 2 cylinders and it makes a very suttle change. So i pulled off the spark plug wires on that cylinder and stuffed a plug in the end and keyed it over. The spark is very weak. I tried all the other spark plug wires and they are very strong. So I tried relocating the spark plug wires to see if its a dead wire. They work good in another cylinder so that elimunates the wires. I pulled the cap off of the distributor and changed the rotor and cap. Nothing, still running on 4 cylinders. I pulled out the distributor and put in another one, same thing. I also changed my coil with another one. Still no dice. Where else can I look? Why is cylinder #3 and #5 weak and the rest strong?

 

[norbs]

have you tried another msd box?

 

[norbs]

The capacitor could be going in the msd box whats the voltage the fast unit is seeing on your screen? Maybe your alternator is not charging when hot i had that issue before.

 

[S2V6RACER]

Here's a stupid suggestion. Swap the wires between 3,5 and see if they fire better. You can set the rotor at #3 then #5 and ground the points wire (on/off rapidly) and see how strong the spark is also.

The MSD box doesn't know what #3 and #5 is, the ECU knows if it's sequential, but I can't see how it could be the ECU in this case. Sounds like maybe bad wiring.

Ohm out the spark plug wires also....