tbi trouble help (1 Viewer)

[blackandbluefj]

ok all have finished the v8 swap to the fj60. used an 88 chevy 350 tbi installed a torquer cam and 305 heads. question is it ran first just great then a plug wire grounded out on the header and it gave me a code 42 and 43. knock sensor was a loose wire and that was fixed. but now i keep getting a code 42 and i just replaced the ignition module which i've been told was it the next thing is the ecm. someone help me out and just stupid this down for me. Ifigure it has to be something simple. so nothing is too stupid. let it fly guys


thanks all


Bryon

 

[Gumby]

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


The EST and BYPASS wires are typically wrapped together in a foil to eliminate as much Electro-magnectic Interferance as possible. If they are run near ignition wires or you stripped the foil when cleaning the harness for the TBI install, or your burnt wire was replaced with one of low quality, you might be getting EMI noise.

 

[blackandbluefj]

thanks i went through the wires and saw afew with some knicks in the insulation and fixed them, and also noticed i must not have pushed the single wire you detach to set timing in all the way and it was loose. now all is good. i knew it was something easy. now who or where does custom chips somewhat reasonable.


thanks all

Bryon

 

[Isotel]

thanks for the info Gumby! I get a 42 intermittently too!