Stalling hot - is mechanic right? Swap ECM?

My 1989 Dakota (3.9 V6, California) started running rough when cold. This problem progressed and I'd have to get it hotter and hotter before it would run smooth. Finally, it wouldn't run at all. From different suggestions, I've put in a new Distrib. Cap and Rotor, new Fuel Filter,new MAP sensor, new TBI's, and I've checked EGR and PCV valve. About to change wires, but before I throw a lot more $ at new parts - like O2 sensors, TPS's and such, I'd like to know what might be wrong. This thing is so instantaneous, it's almost like somebody flipping a switch back and forth, which makes me think it might be an electrical prob.

The mechanic I have it with now is saying it's the computer (ECM, PCM, SMEC or whatever you call it). Does that sound like the likely cause of this problem that got worse and worse? If it IS the likely cause, which ECM should I get - I've heard it's a bit cheaper to get the non-California version (and that it still works fine and the engine runs better). Will it interchange with the Ca. ECM and run with no problems?

Also, have any of you been busted by a smog inspector (or his seeing-eye dog) for a non-Ca. ECM? Is it just a sticker on the top that they check during the "physical inspection"?

My 1989 Dakota (3.9 V6, California) started running rough when cold. This problem progressed and I'd have to get it hotter and hotter before it would run smooth. Finally, it wouldn't run at all. From different suggestions, I've put in a new Distrib. Cap and Rotor, new Fuel Filter,new MAP sensor, new TBI's, and I've checked EGR and PCV valve. About to change wires, but before I throw a lot more $ at new parts - like O2 sensors, TPS's and such, I'd like to know what might be wrong. This thing is so instantaneous, it's almost like somebody flipping a switch back and forth, which makes me think it might be an electrical prob.

The mechanic I have it with now is saying it's the computer (ECM, PCM, SMEC or whatever you call it). Does that sound like the likely cause of this problem that got worse and worse? If it IS the likely cause, which ECM should I get - I've heard it's a bit cheaper to get the non-California version (and that it still works fine and the engine runs better). Will it interchange with the Ca. ECM and run with no problems?

Also, have any of you been busted by a smog inspector (or his seeing-eye dog) for a non-Ca. ECM? Is it just a sticker on the top that they check during the "physical inspection"?


I would try a coolant temperature senser my ford ran rich when warm did everything this fixed it. Cheap shot to try,if it don`t work. May also be a coil or ingnition modual. I don`t think a ecm is it but don`t know for sure. I would go get a second opion from another mechanic.

Thanks, Who Fan. Yeh, that sounds like a likely cause and a cheap fix, as well. And pretty easy to replace.

I also ran into somebody with an '88 Dak that had similar trouble when the "reluctor" rusted out and got loose. This is apparently some little gizmo underneath the Hall Effect sensor in the distributor, that actually tells the plugs when to fire. And that seems to be the problem that this mechanic is trying to fix.

So I'll replace both of these and see which one (I hope) fixes it.

Don`t forget to let us know what you find thanks!