MSD causing code 42 ?????

[Blazin Obsession]

I recently installed a MSD 6AL on my 1988 K5, I am getting a code fault 42. Also is running rich, but no O2 fault ???

Is this because of the MSD or the stock ignition module or ????????

I am stumped on this one, any help would be great.
thanks
Ken

 

[Hossbaby50]

TheRobZilla had a similar problem with his TPI setup and MSD. He said it causes ghosts in the computer sometimes. I believe one of his codes he would get sometimes was 42.

I was going to reinstall my MSD 6 Offroad box with my new TPI system but he convinced me not to because of the gremlins it can cause.

I don't know how wot fix your problem but the MSD might be causing it. You might call MSD and see what they say.

Just out of curiosity did the MSD do anything on an FI rig? Did you notice any gains at all? I did when I installed the MSD on my carbed motor. Thanks

Harley

 

[Bruiser]

That would make sense. Since I have gotten the same code on a car I have been working on. It is a basic a check on the ingnition module returned a out of range value. So maybe it does a check to the MSD. I can scan what wires it says to test to see what is causing it. It could be as simple as a loose wire.

What happens when it sets code 42 is it uses a preset timing curve. So depending on your engines stats could be cause the running rich.

Let me know if you want this diagnostic directions to find out where the fault is.

 

[Thunder]

I had nothing but problems with a 6al in my TBI blazer. The ECM did not like it. I fixed it by taking out the MSD and installing it in my boat.Where it works just fine.
Acually your stock ignition is very good. Just put on a better coil and call it good.

 

[Blazin Obsession]

Thanks for the help.
I have noticed a good difference after installing the MSD and will keep it, I am not happy about the code 42 but can live with it. I will check for loose or poor connections today as well I will call MSD and see what they have to say.

I will post what I find out about this problem tonight.
Ken

 

[dyeager535]

What exactly is code 42? I will guarantee that if it is indeed running on a preset timing curve, your engine is running worse with the MSD than it would be without it, and no code 42.

If it runs better now, then I would suspect you had something else wrong in the first place. No offense, but codes do not make the engine run better.

Not only that, but if it's running on preset timing, (and someone that knows for sure can chime in) it more than likely is ignoring the knock sensor, which although not critical, at least attempts to prevent engine damage.

 

[K5MONSTERCHEV]

Code 42- EST Circuit.

When the system is running on the Ignition Module, that is, no voltage on the by-pass line, the Ignition Module grounds the EST signal. The ECM expects to see no voltage on the EST line during this condition, If it sees a voltage, it sets a Code 42 and wont go into EST mode.

When RPM for EST is reached (around 400 RPM) and by-pass volatge is applied, the EST should no longer be grounded in the ignition module so the EST voltage should be varying.

If the by-pass lone is open or grounded, the ignition module wont switch to EST mode, so the EST voltage will be low and Code 42 will set.

If the EST line is grounded, the ignition module will switch to EST, but because the line is grounded there will be no EST signal. Code 42 will be set.

Problems.
EST line open or grounded
Bypass line open or grounded

A scan tool wont have any ability to help diagnose a code 42 problem.
A PROM not fully seated in the ECm can set a Code 42.

Hope this helps, I will try and get a diagram up later.

 

[Smitty]

Might try giving the MSD tech line a ring. If this is something common they may have a fix. I'm running an MSD unit on three different vehicles without any problems.

 

[Bruiser]

"The EST system is designed to optimize spark timing for better control of exhaust emissions and for fuel economy improvements."

"A backup spark advance system is incorported in the module in case of EST failure"