genhawk21
Active Member
So the SPOUT and the IDM have a matching signal. That’s good. It sounds like they’re either getting the wrong signal or the base timing is off.
I don’t know how to test the signal. I may be able to find it, but you’re probably going to need a scope to see it.
If the ECM is sending the wrong signal, it’s probably because another sensor is lying to the ECM. The output is only as good as its inputs. Let me do a little research and see what I can find.
Thanks Snoranger. I have a few other questions -- pardon me if they're dumb.
First, is there any way the CPS can be implicated in this? From everything I think I understand that would be no, because a troubled CPS would cause a no-start under all conditions. Also I assume that's what's providing the input that changes the voltage on the SPOUT/IDM tests. I only ask because it looks like it's been replaced fairly recently and the wire routing is... strange. The ground wire has been tampered with but seems to be operational. I did test it and it seemed to be ok. But I could easily be mistaken (not confident in my testing abilities).
Second, is there any reason this truck should have the black ICM? (1993 2.3). It has a grey one. I believe this is the correct one and so did the last mechanic it was at. However, even if it was the wrong ICM I don't think we get a no-start, more like a run-weird. The ICM before this one was also grey and didn't look like it was the original one. Everywhere I go on this truck are signs someone has already gone down the same path with this issue. I have been looking for spare ICMs at the junkyard but they get pulled instantly so I haven't found one yet. I was hoping to at least see one to determine if the stock 93-94 ICM was the black one or the grey one.
Finally, I don't know how to test the base timing myself. I do know that if the SPOUT jumper is disconnected, the truck starts and it continues to run well if the jumper is put back in. If it's left out it runs like poo (stumbles) after it gets warm. I feel like if the base timing was off, it would never run well. But it does run very nicely and has good power (for a 2.3). In fact it seems to run perfectly except for the giant annoyance of having to remove the SPOUT jumper to start it, and then replace it.