Question about 1988 Ford Ranger

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1988 Ranger failed CA smog test (badly)

Just bought it from auction for $400, took it to get smogged and failed Gross Polluter levels:

15mph test HC 436ppm, CO 1.46% (specs are 127ppm, 0.78%)
25mph test HC 320ppm, CO 1.28% (specs are 108ppm, 0.99%)
It also failed the ignition timing check because the idle speed was at 1050rpm (spec 750-850rpm)

I want to know if this can likely be fixed without a great expense, if I slow down the idle speed, replace the plugs (and distributor cap, HT leads) and clean the air filter is that likely to help or have i bought an old dog??

Posted by philip_chapm on


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Replace the catyletic convertor and clean egr ports of the intake manifold and all should be well if this has a mechanically sound engine

Posted on Jul 15, 2015


Colin Stickland

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Pull head off and grind the valves in,this should help reduce the levels ,also check the pistons and bores if ok or look it then rebuild and try it again

Posted on Jan 10, 2009

  • rzm39 Jul 30, 2011

    Rebuild?? are you serious? What you need to do first is drain any old fuel out, get new fuel, change out the air filter, plugs and wires and dist cap. Get some carb claener and spray the hell out of the carb or throttle body, also spray out the PCV Valve too. In ca you can get a 1 to 2 mo moving permit for repairs, drive it and out some fuel system cleaner through it. use three to four bottles per tank rather than one.. that might help.

  • Colin Stickland
    Colin Stickland Jul 30, 2011

    need some info here please ,on a vehicle this age in USA does it have a cat ?? as these were not legal requirment here in europe till 1992 ,So without more info i cannot comment but i still say a good head overhaul will help to restore compression ,Using fuel cleaner will not do the cat any good if fitted ,if it does have a cat then check the O2 sensor as it will only have one but if you reply with more details of this motor then i will tell you how to test the O2 sensor with a multimeter and go from their .Sorry but iam a europeon mechanic and never seen a ford ranger till the last year when the electric company bought a fleet of these vehicles for off road maintenance of overhead cables .



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next the timing is regulated by centrifugal advance if electronic or points and by the crankshaft position sensor if ECM controlled ( some after market distributors that are used in place of points units have a small sensor in the distributor that can adjust the timing according to engine rpms, but it cannot make allowances for mixture and so they can advance the timing but not take into account anything else which sometimes results in detonation under certain throttle settings
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