'94 1.9 eratic iddle

[vabeach]

My 94 1.9 has an eratic idle.It goes from almost stalling to about 1000rpm and back constantly.It usually will cut off if left alone.I have replaced the fuel filter and run cleaner through it but it still does it.Any ideas?

[panzees36]

My daughter's 1993 was doing that and it was the throttle position sensor.

[jman63]

my '94 pony did the same thing...it was the throttle position sensor.

[twlunn]

These are from some posts I found when researching my problem about jerking & bucking.

Thought they might come in handy dow the line...

Might check this out:

"

• The IAC simply controls the airflow to maintain your engine’s idle. When it is faulty your engine will not idle correctly.
• The IAC (Idle Air Control Valve) is on top of the intake manifold, where the large hose from the air filter connects to the manifold (basically, right on top of the throttle body). The part is pretty cheap and can be replaced in 5 minutes. Be sure to replace the gasket as well. its on top of your throttle body, looks like a little motor thing.....Take it off and spray it out a few times with WD-40....worked for me, make sure its plugged in too.

[A. Souphound]

I agree with all the posts above. I have fixed cars that hesitated at different speeds by replacing the Throttle Position Sensor. The TPS is nothing more than a rheostat (variable resistor) and can be checked with a VOM to determine if it is faulty and needs replacement.
I have also fixed cars with idle problems as described by removing the air bypass valve, dis-assembling the solonoid from the valve itself, and oiling the orfice tube where it slides into the solonoid. This also improves acceleration, if it was sluggish. A quick check to determine if the Air Bypass Valve is working at all....disconnect the connector and the RPM should drop.

[vabeach]

Where is the by-pass valve located?

[gettoraiver]

Originally Posted by A. Souphound

I agree with all the posts above. I have fixed cars that hesitated at different speeds by replacing the Throttle Position Sensor. The TPS is nothing more than a rheostat (variable resistor) and can be checked with a VOM to determine if it is faulty and needs replacement.
I have also fixed cars with idle problems as described by removing the air bypass valve, dis-assembling the solonoid from the valve itself, and oiling the orfice tube where it slides into the solonoid. This also improves acceleration, if it was sluggish. A quick check to determine if the Air Bypass Valve is working at all....disconnect the connector and the RPM should drop.

Most of all ford tps's test normal even if they are dead.
when you take off the tps make sure you look at the condition
of the throttle part that sticks into the sensor because i have
seen that rusted out and makes it idle like shit. Mine got so back it
was starting to idle at 3500 and it was pissing me off i ended up getting
a new throttle body.

[chevyn0va1]

Originally Posted by A. Souphound

I agree with all the posts above. I have fixed cars that hesitated at different speeds by replacing the Throttle Position Sensor. The TPS is nothing more than a rheostat (variable resistor) and can be checked with a VOM to determine if it is faulty and needs replacement.
I have also fixed cars with idle problems as described by removing the air bypass valve, dis-assembling the solonoid from the valve itself, and oiling the orfice tube where it slides into the solonoid. This also improves acceleration, if it was sluggish. A quick check to determine if the Air Bypass Valve is working at all....disconnect the connector and the RPM should drop.

Do you have any pics of these parts? that air bypass on top of the thottle body? if it is the same thing I took mine off once and sprayed it with cleaner and then wd 40.

[A. Souphound]

Originally Posted by gettoraiver

when you take off the tps make sure you look at the condition
of the throttle part that sticks into the sensor because i have
seen that rusted out and makes it idle like shit. Mine got so back it
was starting to idle at 3500 and it was pissing me off i ended up getting
a new throttle body.

gettoraiver,
You say "Most of all ford tps's test normal even if they are dead."
I disagree, if the method you use can not determine 'good' from 'dead' TPS then it hasn't been tested properly.
A TPS may be tested on or off the vehicle using a DVOM. Testing the TPS will help locate burned or open spots in the variable resistor inside it.
FYI: The proper test method is:
1. Connect one lead from the DVOM to the center terminal of the sensor. Connect the other lead to either one of the remaining two terminals.
2. Set the DVOM to the 20K ohm scale. Depending on the type of sensor, slowly turn the TPS while watching the meter. The meter reading should increase or decrease smoothly as you operate the sensor. Glitches or momentary infinite readings indicate a defective sensor, and should be replaced.