My 92 started misfiring and sometimes stalling out last week. Does it more when hot than cold. Doesn't make a difference on driving style or speed. I cleaned the contacts in cap and rotor but that didn't help either. Just looked in two guides at home plus searched in this forum board for previous people with same problems (I never post anything because someone else already has). Seems like a ton of people are or have had the same problem but with different causes.

Every one seems to have their suggestions of what the possible causes are, so I am going to post suggestions from a Haynes book written in 2004 and from a Motor's book written by The Hearst Corporation in 1970! It is kinda fun to take a look back to one of the pinnacle years of automotive performance and see how much nothing has changed since!

Hopefully this will help us from our tunnel-vision. Check it out (hopefully I can figure out how to post this):

 

<table border="0" cellpadding="0" cellspacing="0" width="1790"><colgroup><col style="mso-width-source:userset;mso-width-alt:65462; width:1343pt" width="1790"> </colgroup><tbody><tr style="height:15.0pt" height="20"> <td class="xl65" style="height:15.0pt;width:1343pt" height="20" width="1790">ENGINE STALLS (per 2004 Haynes Repair Manual):</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Idle speed incorrect. Refer to the VECI label.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Fuel filter clogged and/or water and impurities in the fuel system.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Distributor components damp or damaged.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Fault in the fuel system or sensors.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Faulty emissions system components.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Faulty or incorrectly gapped spark plugs. Also check the spark plug wires.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Vacuum leak at the carburetor/throttle body, intake manifold or vacuum hoses.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">
</td> </tr> <tr style="height:15.0pt" height="20"> <td class="xl65" style="height:15.0pt" height="20">ENGINE STALLS (per 1970 Motor's Automobile Trouble Shooter):</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Engine idle speed set too low.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Large air leaks in intake manifold such as a disconnected vaccum line.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Ignition points need attention.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Vapor lock.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Over-supply of fuel (flooding).</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Valves set too tight.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Throttle return check linkage out of adjustment or check valve leaks.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">If engine quits smoothly when car is in operation:</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Sudden lack of fuel (fuel tank empty, vapor lock, flooding, water in fuel, frozen fuel line, carburetor icing).</td> </tr> </tbody></table>

 

<table border="0" cellpadding="0" cellspacing="0" width="1790"><colgroup><col style="mso-width-source:userset;mso-width-alt:65462; width:1343pt" width="1790"> </colgroup><tbody><tr style="height:15.0pt" height="20"> <td class="xl65" style="height:15.0pt;width:1343pt" height="20" width="1790"> <table border="0" cellpadding="0" cellspacing="0" width="1790"><colgroup><col style="mso-width-source:userset;mso-width-alt:65462; width:1343pt" width="1790"> </colgroup><tbody><tr style="height:15.0pt" height="20"> <td class="xl65" style="height:15.0pt;width:1343pt" height="20" width="1790">ENGINE MISSES THROUGHOUT DRIVING SPEED RANGE (per 2004 Haynes Repair Manual):</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Fuel filter clogged and/or impurities in the fuel system.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Faulty or incorrectly gapped spark plugs.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Fault in the fuel or electrical systems.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Incorrect ignition timing.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Cracked distributor cap, disconnected distributor wires or damaged distributor components.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Defective spark plug wires.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Faulty emissions system components.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Low or uneven cylinder compression pressures.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Weak or faulty ignition systems.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Vacuum leaks at the carburetor/throttle body, intake manifold or vacuum hoses.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">
</td> </tr> <tr style="height:15.0pt" height="20"> <td class="xl65" style="height:15.0pt" height="20">ENGINE MISSES AT IDLE SPEED (per 2004 Haynes Repair Manual):</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Spark plugs worn, fouled or not gapped properly.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Fault in the fuel or electrical systems.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Faulty spark plug wires.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Vacuum leaks at intake or hose connections.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Uneven or low cylinder compression.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">
</td> </tr> <tr style="height:15.0pt" height="20"> <td class="xl65" style="height:15.0pt" height="20">ENGINE MISFIRES AT ALL SPEEDS (per 1970 Motor's Automobile Trouble Shooter):</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Fouled spark plug or broken porcelain.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Faulty spark plug cables.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Low battery voltage.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Low generator voltage.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Burned or pitted ignition points.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Incorrect ignition point gap.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Faulty condenser or coil.</td> </tr> <tr style="page-break-before:always;height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Weak spark or no spark in one or more cylinders.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Faulty distributor cap or rotor.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Primary circuit restricted or open intermittently.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Primary circuit detoured by short intermittently.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Secondary circuit restricted or open intermittently.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Secondary circuit detoured by short intermittently.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Blown cylinder head gasket between cylinders. Noted when missing occurs in two adjacent cylinders.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Sticking valves.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Hydraulic tappet holds valve open slightly.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Broken valve spring.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">leak at intake manifold gaskets.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Mixture too rich or too lean.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">
</td> </tr> <tr style="height:15.0pt" height="20"> <td class="xl65" style="height:15.0pt" height="20">ENGINE MISFIRES AT HIGH SPEED (per 1970 Motor's Automobile Trouble Shooter):</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Hot spark plugs. Note that a hot plug may be due to loose installation.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Ignition point gap much too wide.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Breaker arm binding or sticking.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Breaker arm spring weak.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Sticking engine valves.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Valve springs too weak to close valves promptly.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Valve springs broken.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Valve springs shimmy.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Intermittent delivery of fuel to carburetor so that momentarily the mixture is too weak for combustion.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Mild vapor lock.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Weak spark.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Exhaust manifold clogged with carbon.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Exhaust manifold, muffler or tail pipe restricted.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Improper ignition timing.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Centrifugal advance not functioning properly.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Manifold heater valve held closed.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Dirty carburetor air cleaner.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Choke valve not completely open.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Carburetor throttle lever loose on shaft.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Improper fuel pump operation.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Pre-ignition.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Incorrect valve timing.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">
</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20"> ENGINE MISFIRES AT LOW OR IDLE SPEEDS (per 1970 Motor's Automobile Trouble Shooter):</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Faulty spark plugs.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Spark plug gaps too narrow.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Dirty or corroded secondary circuit connections or faulty ignition cables.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Cracked or faulty distributor cap. Radial contacts in cap burned or worn.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Dirty air cleaner.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Leaky valves.</td> </tr> <tr style="mso-height-source:userset;height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Ignition point gap too narrow.</td> </tr> <tr style="height:15.0pt" height="20"> <td class="xl66" style="height:15.0pt;width:1343pt" height="20" width="1790">Faulty carburetion due to: (a) float level too high or too low; (b) float valve leaking; © incorrect or loose jets;</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">(d) restricted or partially clogged idle air passage or jet; (e) air leak occurring between upper and lower body;</td> </tr> <tr style="page-break-before:always;height:15.0pt" height="20"> <td style="height:15.0pt" height="20">(f) air leak occurring around carburetor throttle shaft.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Air leaks in intake manifold or carburetor resulting from:</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">(a) loose manifold connections or leaks occurring in vacuum lines; (b) loose manifold nuts or capscrews; </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">© broken or damaged intake manifold or carburetor gaskets; (d) craked manifold; </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">(e) warped or damaged manifold contacting surface.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Slight leaks occurring at fuel pump check valves.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Air leak occurring around intake valve stem because of excessive valve stem-to-guide clearance.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">
</td> </tr> <tr style="height:15.0pt" height="20"> <td class="xl65" style="height:15.0pt" height="20">ENGINE MISFIRES WHEN CAR IS ACCELERATED (per 1970 Motor's Automobile Trouble Shooter):</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">The spark plugs stop firing because of increased compression pressure caused by:</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Weak spark.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Plug gaps too wide.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Plug fouled or damp.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Plug porcelain below par.</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Flat spot.</td> </tr> </tbody></table></td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">
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