Regarding my other post- one engine died cruising at 3000 rpm & won't restart. This happened 3 times in one day, the last time it would not restart......the code reader would only bring up two codes #42 & #43- ignition bypass.....
What do the codes mean & what is "ignition bypass" ???

ttt
I cannot believe no one on this board knows the codes !!!

42=EST/BYPASS FAILURE TYPE 2 and applies only to 454/502 MPI's

That much info is on the reader display for #42. but nothing for #43 !! What does ignition bypass fail mean?
I have weak spark out of the coil. replaced with working coil & ecm. No help. won't start...????

Check the thread in GD.

My 1997 manual has 454-502-MPI-8.2 MPI code 14 engine coolent temp. code 21 throttle position sensor.code23 intake air temp. code 33 manifold absolute pressure. code 42 ignition control.calibration memory failure code43 knock sensor. code 51 calibration memory failure.code 69 woman on board

Hey BF, I sent you an e-mail..

I performed "due diligence" last evening & went to the shop where this is being worked on. They were totally focused on the codes rather than troubleshooting or even using "the merc manual". I looked & studied their Merc manual & found this:
There is a Section with my EXACT trouble!!! Cranks but won't start. If this diagnostic, the description of the IC & ECM & distributor & coil interface AND the codes, you have to come to the conclusion it is either a 10 amp fuse or the IC module. It will be changed today & we will see. Fingers are crossed !!

Usually, when code 43 is up, it usually means the knock sensor is unplugged or malfunctioning. If it does not sense the knock sensor, it locks the timing in a pre set timing program.

Thanks,
Dustin

I had a 43 code once that turned out to be loose power butt connector under the dash. When I would hit some rough water the bad connection would short or temporary open and spike the ECU causing a code 43 and setting the ECU into the no spark advance mode.

Hope your issue is just bad components!