Hello all,

I have an 89' IROC that failed (HC too high) the People's Republic of Kalifornia emissions test. The cause of the failure was that the HC level was too high, the reason for this was not disclosed, but a trip to the local auto parts store and $32.00 later gave me some insight. The codes generated were 12 and 42.

I understand that 12 is typical, and that 42 is described as "42 Electronic Spark Timing (open or grounded)." My question is, what the heck does that mean? EST open means nothing to a one wire HEI guy.

On face value, I suspect the problem is because the previous owner replaced the stock coil and dist with aftermarket products. For those in the know, would this be considered at least a potential cause? There is also a female "plug" near the coil that is connected to... nothing. I've taken some pics of the current setup and hope to have them on my site by this evening. That address is: http://132.239.181.37:8091#89iroc

Thanks for your time and any info you might have!

 

When the smog tech checked for base timing, he disconnectected the EST bypass line, most likely that's why you have a "42" there

Disconnect the battery (or ECM fuse) and for a few minutes, then fire her up and run it for a while, see if the "42" comes back.

 

Thanks for the post! I thought that it might be that the base timing would be used for the smog. If one were to leave the suspect plug unplugged, do you happen to know where I might look?

In any case, thanks for the info!

:hail:

 

If left unplugged, the SES light shoul be on, but on my car, it's between the pass. strut tower and fender.