91' tech acting up

I am hoping someone give me a starting point on tracking down an intermittent tech problem on my 91' 2.3L Stang. Unfortunately the motor I have is not included in the Haynes manual I picked up years ago and they never followed through on sending me the latest additions to the manual. I have the 2.3L with 8 spark plugs (electronic ignition - 2 coil packs). Any idea where I should start my search.

Thank you in advance

Reply to
Slightly Graying Wolf
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"Slightly Graying Wolf" wrote in news:DJxLe.213425$s54.7002@pd7tw2no:

what kind of problem..

if you mean "TACH", then I assume it's the problem where the needle intermitently goes to about 3 grand or a little more then varies a little with the engine speed then it's in the tach head itself.

I suspect it's a component (probably internal voltage reg) and it isnt really fixable... just head to the salvage yard and get a new cluster, then replace the tach part.

Reply to
Backyard Mechanic

No, sorry I should have specified (and yes I meant tach) the tach drops to zero while driving or idling for short periods of time - then the check engine light comes on (presumably because the computer needs to know the RPMs) as soon as the tach jumps up to the correct RPM the check engine light goes out.

Reply to
Slightly Graying Wolf

"Slightly Graying Wolf"

Okay... that's a WHOLE lot different. Does the engine idle quality change?

I think the problems have common source and it shouldnt be in the tach, It would be in Crank/cam position sensor.. or in the DIS module itself.

It would be very poor engineering for the PCM to look at the tach Since the CEL comes on, hie thee to autozone to have the codes read out. Make them give you the code numbers, not just the definitions, and do a google on the codes and post them here.

Reply to
Backyard Mechanic

Idle quality/ engine performance does not change very noticeably (maybe a tad hesitant on acceleration).

I will try to get the codes read next week - no AutoZone's around but I have family friend who owns a garage - just a bit of a haul to get there.

Thanks for the help

Reply to
Slightly Graying Wolf

The code is #218 "No ignition monitor signal"

The problem did not happen on the way to work today so it made me wonder if this could be a battery/ alternator problem as it usually happens at idle under heavy load on the electrical system - A/C, radio, headlights (day time running lights - Canada).

The guys pissed around with it for an hour or so discounting anything I said... charging system was 12.1 Volts under full load - Then it happened with the tester on the battery (it dropped down to 11 volts) until I revved the engine and the problem went away again (then the voltage returned to

12.1).

The mechanic then pulled the small plug off of the alternator and duplicated the problem.

Looks like all I need is either a new battery or alternator (or both).

Reply to
Slightly Graying Wolf

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