Analyzing Poor Performance Issues is not easy and may be one or many faults at the same time.
If you suspect that there’s an internal problem that’s leading to a loss of power/performance, you would take the vehicle to a mechanic. Once there, there are certain things that must be done prior to replacing parts or performing service.
You have to know what the problem is before you can know how to fix it.
When a problem develops in a system that is monitored by the computer, codes which relate to the particular system will be set and retained in computer memory. When this happens, the check engine light on the dash will illuminate.
If the light stays on continuously this is called a hard fault – this is the easiest problem to find because the problem is there, right now. If the light comes on and goes out, the fault is intermittent, meaning the problem was there momentarily but has cleared up. Both of these conditions will set computer codes that are retained by the computer.
When Analyzing Poor Performance Issues, it is important to take a logical and methodical approach, and to fix what is known to be wrong first, instead of assuming that it could not be the main culprit.
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The following are basic guidelines for diagnosing each condition, with the most likely cause first:
- Rough idle: Misadjusted carburetor, vacuum leak, worn/misadjusted breaker points, coil polarity wrong, fouled plugs Lack of power
- Insufficient ignition advance, secondary butterfly on carburetor not opening, metering rods/power valve not functioning, restricted exhaust, starving for fuel Pinging
- Excessive ignition lead, carbon-laden pistons and combustion chambers, lean mixture, high cylinder-head metal surface temperature/coolant, EGR (if equipped) not functioning, ignition timing scatter from worn distributor bushing Hesitation
- Weak accelerator pump stroke, vacuum advance not functioning, idle mixture screws set wrong, vacuum leak, insufficient amount of base timing Stalling
- Idle speed set too low, massive vacuum leak, idle circuit in carburetor blocked, EGR valve stuck open, choke tension (when cold)Oil smoke on startup only
- Worn valve guides/seals Excessive oil consumption
- Wrong oil viscosity, oil diluted with gasoline, worn oil ring on piston, excessive cylinder bore wear/glaze, short trips/numerous cold starts
Diagnosing a problem often takes more thought than actual work with your hands. Time spent analyzing the situation is more effective than having wrenches fly.
Taking your time doing proper diagnostics will pay off in the end.