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Asked: Jun 28, 2009 - 06:35 PM

Status: Closed

1988 Plymouth Horizon has no acceleration power at all.

1988 Plymouth Horizon that has no acceleration power. No fault code showing. Have done checks on coil and all censors(all checked good). Changed fuel filter, air filter, spark plugs(with correct gap), spark plug wires, distributor cap, and rotor.

The engine idles great, but when you accelerate the engine speed (in gear or out), it seems as if the distributor is not advancing with engine speed. I have researched it as much as I seem to be able to and it seems like it may be stuck in idle mode.

I know this car has a "limp home" mode the computer initiates, however, with the absence of any fault codes from the computer, I think the Hall Effect Pickup Assy may be faulty. At this point, any help or suggestions would be greatly appreciated. Thank you in advance for any input.

In Makes & Models > Plymouth > Horizon
In Maintenance & Repair > Engine
2 answers - 150 days ago

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zaken1

Date: Jun 29, 2009
Time: 02:42 AM

You can confirm or disprove that the ignition timing is not advancing with engine speed by watching the timing marks with a timing light while the engine is idling; and then seeing if they advance when the engine is speeded up. If the timing does not advance when the engine is speeded up; the ignition pick up is probably defective.

If the throttle position sensor was defective; it would cause the engine to stay in idle mode. If the ignition timing was set too far retarded; it could also cause the engine to have no acceleration. It may be necessary to short the terminals in a check connector; it order to disable the automatic advance so that the idle timing can be adjusted. It the timing is set without shorting that connector; it would probably end up being too far retarded. There should be an an instruction on the underhood emission label or in the service manual about any things that must be done before attempting to adjust the timing.

In a situation like this, it would be very important to run a compression check on the engine. If the compression is below manufacturer's minimum allowable specs in one or more cylinders; the engine will not be able to be made to accelerate properly.

The other thing that can cause this problem is a clogged catalytic converter. It is easy to check this; by having someone stand behind the car and hold a hand about 6 inches behind the end of the exhaust pipe, while someone steps on the accelerator. They should feel a blast of exhaust come out of the pipe when the throttle is opened. If there is little or no difference in the exhaust volume when the throttle is opened; the converter is probably clogged.

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avatar

zaken1

Date: Jun 29, 2009
Time: 02:42 AM

You can confirm or disprove that the ignition timing is not advancing with engine speed by watching the timing marks with a timing light while the engine is idling; and then seeing if they advance when the engine is speeded up. If the timing does not advance when the engine is speeded up; the ignition pick up is probably defective.

If the throttle position sensor was defective; it would cause the engine to stay in idle mode. If the ignition timing was set too far retarded; it could also cause the engine to have no acceleration. It may be necessary to short the terminals in a check connector; it order to disable the automatic advance so that the idle timing can be adjusted. It the timing is set without shorting that connector; it would probably end up being too far retarded. There should be an an instruction on the underhood emission label or in the service manual about any things that must be done before attempting to adjust the timing.

In a situation like this, it would be very important to run a compression check on the engine. If the compression is below manufacturer's minimum allowable specs in one or more cylinders; the engine will not be able to be made to accelerate properly.

The other thing that can cause this problem is a clogged catalytic converter. It is easy to check this; by having someone stand behind the car and hold a hand about 6 inches behind the end of the exhaust pipe, while someone steps on the accelerator. They should feel a blast of exhaust come out of the pipe when the throttle is opened. If there is little or no difference in the exhaust volume when the throttle is opened; the converter is probably clogged.

avatar

flamingdeath

Date: Jun 29, 2009
Time: 12:45 PM

Thank you Zaken1. The timing was the issue. It was retarded too far. After retiming, the car runs great! Thank you again for quick response and great advice (my grey hair thanks you as well :D ).

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