ignition/ poor running problems

Brian Devlin bdevlin at stanford.edu
Mon Feb 4 13:56:39 EST 2002

This problem is could be caused by a variety of failures, and all we
can do for you is guess. Since it is intermittent, it probably is an
electrical failure in the engine managment. Could be fuel, could be
ignition (could be both?).

First check+fix all the grounds.
Have you confirmed that the timing changes with a timing light?
Do you have a good voltmeter to look at the mixture (O2 sensor output)?
Have you looked at the current to the frequency valve?

If these don't reveal a problem then start randomly yanking on wires
until "the condition" appears. If that doesn't do it, then start
unplugging things.

Other semi-useful info:
- the 84 JT did not have a knock sensor or fuse slot in the fuel pump relay.
- if there is a spark delay module, then it can be bypassed, just
join the in+out connectors together IIRC.


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