1992 Ford Tempo Runs/Idles Rough, Low Power

09-12-2011, 11:08 PM
My father and I have spent the past two weeks attempting to pinpoint the problem with a 1992 Ford Tempo (96K miles) with a 2.3L 4 cylinder HSC engine with no luck. We are completely baffled as to what it could be, and would love it if somebody here had an idea.

The car starts fine when cold but will sometimes require two or more attempts if it was running recently. It runs rough and lacks power at all times, but gets worse when it is hot, to the point of stalling at idle. I can push the gas pedal to the floor and it doesn't accelerate any faster than if it were at half or less. The check engine light does not come on and there are no stored OBD-I codes. The exhaust also tends to smell of unburned gas.

Also, the radio sometimes dies at random and then works again. I don't think that's relevant, but I'll be complete.

We have tested the following things and determined that they are working properly:

MAF Sensor - When disconnected, check engine light came on and car ran worse, multimeter tests were fine.
Throttle Position Sensor - Smooth resistance increase
Fuel Pressure Regulator
Air Bypass Valve
EGR Valve - Blocked off from intake manifold and noticed no improvement
Ignition Control Module - Tested out with multimeter
Ignition Coil
Engine Compression - all 4 cylinders were 150 +/-5 psi, which is within the acceptable range
Fuel Injectors - These were ridiculously dirty and squirting fuel in a straight line, but did not improve performance at all after being cleaned.
Fuel Pump - Pressure at test port is correct, can hear it running when applying 12V
PCV Valve - Not blocked
Vacuum Hoses - Checked for leaks with stethoscope
Ignition Timing - Used timing light, marker lined up with 10 degrees BTDC, exactly the correct value.
Spark Plugs and Wires - Checked wires. Spark plug #1 was significantly worse looking than the others and the gap might have been a bit small. We had replaced the spark plugs before this and it didn't seem to help.
Plugged Catalytic Converter/Exhaust Backpressure - Ran car with exhaust connection to EGR Valve disconnected, no change
Air Filter - Checked/replaced

We have taken off the distributor cap and visually inspected it and the rotor and all appears fine. We have not replaced any distributor parts.

We also tested the intake manifold pressure and it was 16 in-Hg, which is on the low end of acceptable. It tested at 12 at one point, but I'm pretty sure we had something disconnected at the time.

Finally, about a month ago, the alternator failed and had to be replaced.

I have no clue what could be going on, and I'd be grateful if someone could come up with an idea.

02-20-2012, 05:18 PM
Make sure the pump is reading the correct Psi. If not tempo's and topaz's have the same issues, Have you tested the MAP sensor?. what about IAC motor is another common issue.

Add your comment to this topic!