1987 code 42
 

Hi to all,


Ive got a 1987 chevy 1/2 ton with 305 and th400. Ive got a random code 42 that is kicking my butt. So far I have put 2 ignition control modules in, both GM. And I have put a used computer in. Every time I change out something it waits a couple weeks and then sets the code 42 and I can feel the difference in the engine and the shifting of my transmission. Its random though. After 2 weeks or so of replacing a part, it will then set and randomly die and randomly run rough. Any help would be appreciated.


Josh

Re: 1987 code 42
 

Code 42 troubleshooting flow chart

TBI ignition system should be the same as 1986 - 89 ignition

Re: 1987 code 42
 

Thats the problem, it is intermittent.

Re: 1987 code 42
 

This guy on his 91 burb fought it intermittent. It was a good read, maybe help you out.

http://www.gmtruckclub.com/forum/sho...-1991-Suburban

Re: 1987 code 42
 

Not to thread Jack but it seems weird a half ton with a 305 would come with a th400 in 87
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Re: 1987 code 42
 

It was an Oklahoma State Park truck. I guess they only needed 3 speeds.

Re: 1987 code 42
 

Still weird a 400 and not a th350 no offense but I'm surprised that 305 can even turn the pump on a 400
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Re: 1987 code 42
 

I don`t think they had 350 turbos in 1987 , only 700r-4 and 400 turbo. My 87 with a 4.3 has a 400 turbo

Re: 1987 code 42
 

Huh I never thought of that. But what a combo 4.3 th400.lol
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Re: 1987 code 42
 

Get the pinout for your ecm its likely a loose wire causing this issue.
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