84 Duke - 4speed. Good fuel pressure. Car will radomly die....usually when its HOT but not always.
Changed Ignition Coil, Ignition Module and Pick up coil on distributor. Problem still there.
What else could it be?? Im sure someone will say ECM.... but really how often do these things go bad??
The only other clue to a problem that I have is that ever since I've had the dying problem, I notice that the Tach will randomly jump around.

Try pulling your codes to see if anything shows up. Also check your vacuum lines. Try cleaning your ground straps. Maybe even a faulty coolant temp sensor? If I think of anything else, I will be sure to post it. I have the tach dance too right now and am trying to figure it out.

Computers do go bad. I had a failure in my 84. When mine died it went crazy and quit running. My CEL light came on. I tried to pull a code and the computer was not comunicating at all when I jumpered the terminals. (no 12 at the start) Thats how it knew it was bad. The way I got home was to let the ECM cool down. The car would run ok till the computer got hot. I guess there was a loose wire inside that would show itself when the heat caused some expansion & effected the connection. Replaced it and the car was fine again.

You have any common things that occur when the car dies? I know you said hot sometimes, but not always... When the car reaches a certain temp on the gauge? A certain drving distance? A/C on or off? Up hill, Down hill? After hitting a big bump? Anything like this will help narrow down your potential search areas. Will car start right back up after?

Have you had the CEL come on at all? Start by pulling codes & seeing what that shows...

There are no codes, other than a MAP code that got set when I disconnected the map sensor to simulate what might happen if the sensor was bad. (Car continued to run... so..that ain't it!)

Doubt any vacumn issues, as the car runs good otherwise, and gets about 27mpg....as good as its gotten since new

Disconnecting the map sensor will not cause the car to quit. It will throw a code, but the ECM will revert to default parameters in the stored tables to allow the car to continue to run. Performance will likely be off, but that's about it.

I would check for faulty cooland temperature sensors, check if teflon sealant was used on any of the coolant temp sensor threads (they need a clean ground, no teflon tape or liquid), do the shake test for the wiring harness and see if that causes a stumble, check the IAC.... it may need removal and cleaning too. My bet is a cleaning of the IAC.. It could also be ECM related too.

[This message has been edited by Joe 1320 (edited 06-27-2008).]

Clean the TBI and the IAC (and associated passageways)

J.

I had a bad battery ground cable on my '84 that would cause the car to randomly die.

Joe/Jask Im not against cleaning the IAC as Im out of things to check. But what about the IAC would cause the problem to manifest itself primarily when HOT??

Could be just part of the problem and easy to check.
J.

quote Originally posted by edfiero: Joe/Jask Im not against cleaning the IAC as Im out of things to check. But what about the IAC would cause the problem to manifest itself primarily when HOT??

The IAC is directly responsible for idle quality by metering additional air past the throttle blades when those throttle blades are closed. When you open the throttle as in a cruise, the valve restricts flow as it's not needed. When you close the throttle like slowing down at a red light, the IAC opens up to prevent the engine from stalling. Carbon deposits form and will restrict the valve's movement or the passage itself can become restricted. This is most evident when the car has warmed up, ie: hot. Pulling it out and cleaning is a simple task. Unplug the connector from the IAC and unscrew it from the throttle body. Use 02 sensor safe TB cleaner only hold the pintle end downward to prevent the fuild from getting into the electronics portion. Clean the pintle as well as inspect the TB air passage for carbon deposits. Reinstall is the reverse.

It could also be a contributing factor and not the entire cause. Tough to tell unless I had hands on.
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Competition Yellow 84 2.5 Bone stock right down to electrical gremlins

[This message has been edited by Joe 1320 (edited 06-28-2008).]