Don’t Let Repairs Turn Into an Expensive Guessing Game

Question: I have a 1987 Honda Accord with a four-cylinder engine that has developed a peculiar problem. The engine loses power just as I back off slightly on the gas pedal during an acceleration. The engine hiccups, loses power and then regains power all in a second, which causes the car to lurch violently. It can happen at almost any speed, but only after the engine has warmed up. The car has a carburetor rather than a fuel injection system. My mechanic did a tuneup, but that did not help.

--J.M.

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Answer: The hardest thing to fix in an older car is a performance problem that isn’t routine for its model, which is exactly what you have.

Usually, power loss occurs during acceleration or steady speed rather than the transition from acceleration to steady speed. I have asked a number of Honda experts about the condition and even they can’t even put their finger on what would cause it.

In a situation like this, you need to exercise a lot of caution to avoid becoming the victim of an endless series of high cost trial-and-error fixes. The problem is further exacerbated by the technology in your Honda, which exemplifies the nightmare of pre-computer emission control systems. There are dozens of vacuum hoses snaking through the engine compartment to various valves and sensors. With so many vacuum hoses and no self-diagnostic system, your car will be tough to fix.

Honda engineers suggest that the problem may be related to either the exhaust gas recirculation system, which routes a portion of exhaust back through the intake manifold, or the air injection system, which puts extra air into the intake manifold.

Both systems come into play during acceleration and deceleration. They are both operated by vacuum hoses. If you are mechanically inclined, you can attempt to clamp off the hoses near the vacuum valves on the intake manifold body and see if that changes the condition.

You should also check the dashpod, which is the carburetor device that helps control deceleration, as well as the gas tank venting system, since an improperly vented tank can cause all kinds of problems.

* Vartabedian cannot answer mail personally but will attempt to respond in this column to questions of general interest. Write to Your Wheels, 1875 I St. N.W., No. 1100, Washington, DC 20006 or e-mail to Ralph.Vartabedian@latimes.com.