Help! No check engine Light Code 42

[Marv02]

I have NO check engine Light but I do have a CODE 42.
When I first got the car fired up after installing the new motor, I had a Check engine light for Code 42 It end up being a broken wire I fixed it the check engine light went away the car ran great.
I drove it around for 10 to 20 miles then it started to run BAD missing stalling something was amiss.
Now No Check engine light but I now have code 42 again.
Any Ideas I don’t think it the same wire again could be an Ignition Mod Or what.
The car idles Ok but not the best it ides ok then starts acting up missing and cutting out but not idling.
Driving from a stop not a lot power after 1500 to 2000 RPM’s the power go’s flat like it’s not advancing the timing.
The motor has 340+ H/P and 427Tq It should be able to smoke the tire when you stand on it from a stop It will not.

 

[boomdriver]

I have NO check engine Light but I do have a CODE 42.
When I first got the car fired up after installing the new motor, I had a Check engine light for Code 42 It end up being a broken wire I fixed it the check engine light went away the car ran great.
I drove it around for 10 to 20 miles then it started to run BAD missing stalling something was amiss.
Now No Check engine light but I now have code 42 again.
Any Ideas I don’t think it the same wire again could be an Ignition Mod Or what.
The car idles Ok but not the best it ides ok then starts acting up missing and cutting out but not idling.
Driving from a stop not a lot power after 1500 to 2000 RPM’s the power go’s flat like it’s not advancing the timing.
The motor has 340+ H/P and 427Tq It should be able to smoke the tire when you stand on it from a stop It will not.

sounds like the same problem with an old code.
Was the memory cleared after fixing the wire last time?
If there was a short or bad wire to the spark module that can damage it. They fail in different ways. Sometimes nothing at all, sometimes misfiring or timing issues. I think many parts stores can test your module and if it is bad, they're not horribly expensive BUT, use only a Delco. The generic modules are not calibrated as well and I have personally had trouble with the chinese brand that caused knocking and missing at higher rpm.
Be sure to check the knock sensor wire and ESC module if your motor has that seperate piece. The knock sensor has to be torqed at 14lbs. Too tight and it messes with the signal and can cause a false knock signal that causes timing to retard.

 

[vetteoz]

CODE 42

Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system.

During cranking, the timing is controlled by the ignition module while the ECM monitors the engine speed. When the engine speed exceeds 400 RPM, the ECM sends a BYPASS signal to the ignition module which switches the timing to ECM control. The ECM calculates what the timing should be then "tells" the ignition module via the EST circuit.

An open or ground in the EST circuit will stall the engine and set a Code 42. The engine can be re-started but it will run on ignition module timing.

The conditions for setting this code are:

* System in BYPASS mode but the ignition module is still controlling timing

- or -

* Engine speed > 600 RPM with no EST pulses (ECM controlled timing) going to the ignition module for 200 msec.


Typical causes for this code include:

1) BYPASS line is open or grounded
2) EST line is open or grounded
3) PROM or CALPACK not seated properly in the ECM
4) Poor connections between ignition module and ECM
5) Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise)
6) Faulty or incorrect ignition module
7) Faulty ECM

 

[Marv02]

Found it.
The left rear intake runner gasket at the intake base gasket must of shifted last time installed it.
It ran good for a while I guess it let go. it was not centered on the runner.
So I fixed the code 42 new Ignition Mod .
Found why it ran ruff bad gasket.
I ordeed one I sould get by the end of the week.

 

[Hib Halverson]

After the MIL came on the first time and you had DTC42 set and after you fixed the problem, did you clear codes?

If you didn't, the 42 will remain in memory as a history code for 49 ign. cycles but the MIL will not come on.

 

[Marv02]

Yes I did clear the code.

Like I said it was weird I tran great all a sudden it started acting up.

At first there was no code after trying to figure out whats going on and trying to get a code again thats when Code 42 showed back up.

I put a New Ignition Mod, Distribtor cap and rottor in the car no more code but it still was running Crappy.

I stuck my big fat head next to the intake I heard a hissing noise I tryed the carb cleaner trick while it was running Nothing but I can still hear the hiss.

I tore the intake apart and found a bad gasket it looks like it was just hanging on by a very little there where my air leak is at I sure thats why I would not idel and rev out cleanly either.

I sure miss the old days of a Carbs and no computer they were so much easyer to figure out.( Spark Fuel Compression so much easyer back then)

After the MIL came on the first time and you had DTC42 set and after you fixed the problem, did you clear codes?

If you didn't, the 42 will remain in memory as a history code for 49 ign. cycles but the MIL will not come on.