For code 42 what could i do to diagnose my problem a friend said to replace the ignition coil. Could that be my problem?
The problem i have is the car wont start unless i spray some starting fluid.

 

http://www.chevythunder.com/est_code_42.htm

 

Does it stay running ?

 

Yes that is the wierd part after it starts up it runs good.

 

try disconnecting the est bypass wire and see if it starts. My 90 vette used to crank & crank and not fire but when the est bypass wire is disconnected it starts right up. If it did start while it was connected the motor would rattle and have no power, never found out the cause but suspect either the ICM or knock sensor. Kinda has it's good and bad days but lately hasn't ever did it. When I bought the car it had a toggle switch for the est bypass wire and one day found out why that switch was in the car.

 

Oh ok will try that tommorow. Yeah my car has a similar problem because this weekend was starting good just till today started acting up.

 

when it did start on starting fluid did it have detonation? Mine was like a fast rattling noise and then sometimes would just go away and other times just die.

 

Yes! exactly same thing my car is having.

 

Sorry, I don't know what is the cause only that either disconnecting battery or disconnecting est bypass wire would get the car to start and run normally. But this puts the car at base timing so still doesn't have a lot of power but starts everytime like this.

Perhaps someone else can explain better but I heard when tpi is started the ecm max's timing for a second to test the knock sensor response. I have a 7730 ecm or 7727 not sure so my spark control module is internal to the ecm and non serviceable.

Not sure what year you have but there are only 4 things that can cause esc issues

ecm
icm
spark control module
knock sensor

 

Thanks. I will see what other feedback i get since i don't want to just start replacing parts and not fixing my problem.

 

I am having an issue with a code 42 and 45. loud ticking sound on cold start that gradually goes away after 10 seconds. I dont know where to start and already have a new distributor that came with a new ignition module and new knock sensor. I also added MSD 6al box but this didnt affect the ticking sound just seemed to make the code 42 set more often.

 

i have a friend.with a 93 yukon and when he had code.42 problems i think it had to do with the EST. not being grounded


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