88' TBI - Code 42 Help

[Charleshugh]

I'm throwing a code 42 on my blazer and need some help.
Background; I drove it to a neighbors house and when I went to leave I was stuck with a crank and no spark condition - we then sent it to the shop where they replaced the distributor. I got it back and it had an engine light (I'm guessing it was also a 42), I drove it for a week while it acted pretty sluggish and didn't idle right and now it starts but will cut off when I give it any gas whatsoever.
After seeing all of the other forums on this I know it can be caused by a lot of different issues so I'm not too sure where to go from here?
If a distributor is bad out of the box can this throw that code? Would a bad distributor even allow my truck to start?

 

[ktmoutfront]

Did you have the 42 code when it quits, or just after?

 

[gmbellew]

code 42 only sets if the EST or bypass wire are open, grounded, or if they see unexpected voltage.

constant code 42 - open/short in EST or bypass (wire or connector). bad ICM. bad ECM.

intermittent code 42 is from unexpected voltage on EST or bypass - plug wire on ICM or sensor wire (EMI). bad plug wires with cracked cover (volt leakage). cracked distributor cap (volt leakage). loose rotor under cap(volt leakage). Cap with a bad terminal (volt leakage). wiggle the ICM harness and the bypass harness to check for a bad connection or a rubbed through wire.

 

[Wes Harden]

Start by moving the spark plug wires away from the small wires to distributor and coil.

The high voltage in the spark plug wires can mess with the ICM signal to computer.

Did the "new" distributor come with new cap and rotor? If not they need to be inspected for carbon tracting and cracks,

 

[Charleshugh]

code 42 only sets if the EST or bypass wire are open, grounded, or if they see unexpected voltage.

constant code 42 - open/short in EST or bypass (wire or connector). bad ICM. bad ECM.

intermittent code 42 is from unexpected voltage on EST or bypass - plug wire on ICM or sensor wire (EMI). bad plug wires with cracked cover (volt leakage). cracked distributor cap (volt leakage). loose rotor under cap(volt leakage). Cap with a bad terminal (volt leakage). wiggle the ICM harness and the bypass harness to check for a bad connection or a rubbed through wire.

I have a constant code 42 - this helps a lot and makes sense. With the distributor being new, could the ICM have been defective from the factory? Or is it more likely to be a problem with EST or ECM?

 

[Charleshugh]

Start by moving the spark plug wires away from the small wires to distributor and coil.

The high voltage in the spark plug wires can mess with the ICM signal to computer.

Did the "new" distributor come with new cap and rotor? If not they need to be inspected for carbon tracting and cracks,

I'll move the spark plug wires and report back once I get home. And yes the new distributor came with a new cap and rotor and I assume a new ICM and pickup coil as well.

 

[Charleshugh]

I have a constant code 42 - this helps a lot and makes sense. With the distributor being new, could the ICM have been defective from the factory? Or is it more likely to be a problem with EST or ECM?

Before it was sent to the shop I replaced the ICM to see if this would fix the no spark issue but it didn't. I'm not sure if that would have any effect on what it's doing now though.

 

[gmbellew]

I have a constant code 42 - this helps a lot and makes sense. With the distributor being new, could the ICM have been defective from the factory? Or is it more likely to be a problem with EST or ECM?

so the SES light is on constant and you only have code 42? the diagnostics in the emissions and drivability manual can help with that.

 

[Wes Harden]

It can but it's not all inclusive 42 has been a trouble some code for many here.
2 pages worth. Fyi this is for a 90 tbi