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Lately I've been experiencing a drivability problem with our stock Ford Zetec VVC ('98 Ford Contour) powered Seven. The symptom is missing and rough running at very slight throttle openings, similar to what I'd expect from an engine running too lean. The symptom is most noticeable when backing off the throttle to maintain speed after accelerating. At large throttle openings, the engine runs smooth and produces normal power.
At first I thought the problem was a malfunctioning Throttle Position Sensor, and replaced that with a new Ford unit, but to no avail. I've also cleaned the Mass Air Flow sensor (with the proper cleaner) and also the throttle body (again with the proper solvent).
As with most of the '98 Ford Contour Zetec powered Sevens (at least those I'm aware of), my engine's idle speed has almost always been high (1,200 - 1,500 rpm), but recently has been a little more erratic than in the past, sometimes falling to 500 rpm, and other times remaining at 1,600+ rpm. One thought is the Idle Air Control valve is sticking open when it should be closed and allowing excess air to the engine when the throttle is nearly closed, thus causing the lean / stumbling condition. Or, maybe my PCM is going away and not controlling things properly. Does anyone have any advice or experience to help sort this out?
One of the things that makes this condition particularly difficult to diagnose is a problem reading the PCM error codes. The Snap-On code reader/diagnostic tool that most shops (and earlier, the BAR Referee!) use will not communicate with my car's PCM! I took the car to a Ford dealer once, and his diagnostic device did communicate, AND we got lots and lots of error codes since the Zetec installation in the Seven is so different from that in the Contour. Maybe that should be my next step in this search. But, has anyone experienced this problem and found a solution to accessing the error codes without going to a dealer?
Thank-you,
At first I thought the problem was a malfunctioning Throttle Position Sensor, and replaced that with a new Ford unit, but to no avail. I've also cleaned the Mass Air Flow sensor (with the proper cleaner) and also the throttle body (again with the proper solvent).
As with most of the '98 Ford Contour Zetec powered Sevens (at least those I'm aware of), my engine's idle speed has almost always been high (1,200 - 1,500 rpm), but recently has been a little more erratic than in the past, sometimes falling to 500 rpm, and other times remaining at 1,600+ rpm. One thought is the Idle Air Control valve is sticking open when it should be closed and allowing excess air to the engine when the throttle is nearly closed, thus causing the lean / stumbling condition. Or, maybe my PCM is going away and not controlling things properly. Does anyone have any advice or experience to help sort this out?
One of the things that makes this condition particularly difficult to diagnose is a problem reading the PCM error codes. The Snap-On code reader/diagnostic tool that most shops (and earlier, the BAR Referee!) use will not communicate with my car's PCM! I took the car to a Ford dealer once, and his diagnostic device did communicate, AND we got lots and lots of error codes since the Zetec installation in the Seven is so different from that in the Contour. Maybe that should be my next step in this search. But, has anyone experienced this problem and found a solution to accessing the error codes without going to a dealer?
Thank-you,
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