Jun 132013
 

I drive the car and when on low side of gear it will backfire thru throttle body and loss of engine power. Replaced: EGR Valve, EGR Solenoid, Dist.Cap, Rotor, Cables, Plugs, TPS Sensor, Fuel Filter, Oil, Oil Filter, checked for vacuum leaks and found non, Engine power is not loss when not in gear, but backfires the same off gear after engine warms up, I change all that and still does the same thing, mostly when warm. I am in Florida (warm/hot weather). Going to replace PCV Valve today.

  2 Responses to “1992 Isuzu Rodeo w/ 3.1L Engine Manual 5 speed tranny”

  1. The only time an engine can back fire through the throttle body is when the intake valve is open. This would happen for 2 reasons. The first reason would be if a valve was stuck or damaged(not so common) the second would be from faulty ignition timing which would allow the engine to spark to early before the valve is closed(most likely).

    I would check and double check your ignition timing.

  2. I did check the timing and was a little off but I adjusted it. Timing is at 10 @ idle as indicated in the service manual. I even fine tuned it. It has a timing chain and timing chains I know don’t normally jump tooth.. when they go, they go..completely.

    Plus, if it were timing, it would do it no matter what gear I was in low end of gear or high end of gear wouldn’t matter. I am no expert, but i do know this much about engines. I show codes 32 and 44.. I replaced everything for code 32 and checked for leaks and no vacuum leaks. I am tightening my exhaust and replacing the
    O2 sensor to clear code 44.

    In reading your post, I am going to check the valves. Although if it is sticking,I guess I can clean it and see if it helps any.
    And as you said, I will triple check the timing again, just to satisfy doubt.

    I thank you for your insight and help. It does have over 240K miles on it, so it is very likely that valve is sticking considering nothing had been done to this engine for a while. I would say a long while.

    I will post my findings on that later on.

    Again, thank you for your insight.

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