code 42 on 1991 blazer k5

[jojo]

i have a 1991 blazer and i replaced the distributor, spark plugs, spark plug wires and rotor and cap and all the vacuum lines and it keeps giving me a code 42 and according to the book that means an est but i have no idea what this is or where to find it ? could i be one tooth off on the distributor even though i used a timeing light? when in idle position it runs ok when i give it gas it is missing . i have tried all these things brand new parts and still get a code 42 ? what is your advise to try next. according to the book an est is an electronic spark timeing but where is this located and will it fix the problem. thanks

 

[British Slave]

http://www.syty.org/old/d&e-code42.html

 

[jojo]

is this a part that needs to be replaced or can it be done by me

 

[4X4HIGH]

First off i'm assuming after you did all the work you tined the engine correct? In order to time the engine you had to disconnect the EST wire that is located near the brake booster (single brown or tan wire IIRC). Once that wire is disconnected it sets a code 42 in the ECM and it will stay there for awhile unless you disconnect the battery for a few minutes to reset the ECM. I'm going to guess that you did not disconnect this wire and that's why you're having issues with the truck "missing" above an idle.