My car has been sitting for 2 months, (in Michigan-damn snow) I started
it up today and i get a DTC 42. This is what i found on the DTC....


It is Electonic spark timing (EST) circuit-open or shorted to ground
during engine run.

OR

Direct ignition system (DIS) fault-bypass circuit open or shorted to
ground during engine run.

OR

Fuel cutoff relay circuit-open or shorted to ground.

I unhooked the MSD 6AL and MSD coil. Still has to code. I cleared the
code in Lt1 edit but it comes back on right away. Also the fans are
always running now. Another problem I have been having is the spark
plugs and wires. The motor is all rebuilt, only 5K on it. Has taylor
OVC's and NGK TR55 plugs. At night I can see spark going from the boot
area around the plug to whatever metal close by it can reach, they're
arcing throught the boots on almost all eight cylinders. Also the whole
plug lights up when it is firing, (glows orange) All of this stuff
arcing and glowing is only visible at night. The arcing and glowing has
been happening for a while, since like August, seems like ever since i
put the NGK and OVC's on. But, the DTC just started. Any answers???
Sorry for the long post, and thanks in advance.

Jason

94 Z

 

TTT

 

My GM shop manual says 42 is ignition control error. I would think with all the electrical noise from the arcing any trouble code is possible. I would get different mfr wires and probably plugs while your at it replace them and then reset the codes and see if that helps.

If the code returns, check the PCM blue connector to the ICM. Check C27 for resistance to ground with the connector off and key on. C27 should be less than 500 ohms to ground. The other ckt is C28 and it's a little involved but if you need the info for that circuit let us know.

try that for now

 

Thanks, i found the DTC problem. It was the control mod. But the wires still arc at the plug ends??????