I have some kind of problem that is setting off a code 42 ESC on my 92 350 T/A.... ive replaced all components associated with this system on the car b/c they were due, but it still wont clear the code off the computer, and i have a scanner that can clear it. now its also after 3200 rpm it starts like choking and stumbling like its going to backfire or cough... does anyone have an idea what is going on with the car or has had the same problem....??? it also has a small loping idle from sitting at 600-700rpm drops to 500, then spikes itself back to 600-700.......

 

Try all this out,

1)Clear codes, Idle engine until code appears,
check code to make sure it's still 42.
2)Ignition off, disconnect ALDL connectors, Ignition on,
with an Omhmeter probe CKT. 423 on the ECM to ground (BC8),
It should read less than 500 OHMS. Does it
3) 'NO', Open CKT. 423. Faulty Connection or Faulty Ignition Module.
4) 'YES', probe CKT. 424 (BC7) on ECM with a test light to 12 volts and, (note light).
5)Light 'ON', disconnect Ignition module 4-way connector, light
off now (Faulty Ignition module), Light on, CKT. 424 is shorted
to Ground.
6)Light 'OFF', Attach Ohmmetter again to CKT. 423 and ground,
Probe CKT. 424 again with a test light to 12 volts. (As test light
contacts CKT. 424, Resistance should go from under 500 to over
5,000 OHMS. Does It
7)'No', Dissconnect Dist. 4-way connector. Note OHM meter that is
still connected to CKT. 423 and ground. Resistance should have
gone high (open circuit). Does it. (YES) CKT.424 open,Faulty
connections or faulty Ignition Module. (NO) CKT 423 shorted
to Ground.
8)'YES', reconnect ECM and idle engine until service engine light
comes on. (Light on), code 42 present, faulty ECM. (Light Off),
code 42 Intermittnet, no trouble found. Check harness and
connectors for an intermittent open or short to ground in
CKT. 423 and 424.

 

thanks for the info, ill try all of it, hopefully it will solve the prob.... i will post back when i get some time to do it... i work 2 jobs so hopefully next week.... thanks

 

Had the same problem with my 89 gta after a distributer swap, it was a bad ecm. What is actually happening is the computer isnt advancing your timing from the base setting. Put a timing light on it and see what happens, if your timing doesn't advance check to make sure the brown wire you disconnect to set timing is connected if it is its you probably have a bad ecm, theyre not to hard to fry in our cars ive been through 3 since ive had my gta.