Crappy problem - engine stutters/bucks at low rpm

[Joe_Cool]

I've searched and read about a dozen similar threads, but none of them seemed to really be the same problem. So I apologize in advance if this is a repost.

Here's the story:

Car = 1994 Ford Taurus SHO, 3.2L

Problem is that at engine speeds < 2500 rpm, when the engine is warm, it's really weak and kind of sputters when it's under load, like accelerating from 30-50 mph in high gear, for example. It feels like there are cylinders not firing. But once it hits 2500, bam, everything works, and my power comes back. And I mean it's like somebody flicked a switch. Instantly (actually about 2550-2600 rpm) the car is running with all its normal power.

On a cold start (like after it's been sitting overnight), it runs normally, with all the normal power at low RPM. After driving it fro about 10 or 15 minutes, once the engine heats up, the bucking comes back.

I ran the self test and got an EGR code.

I replaced the spark plugs and wires, thermostat today, and am currently battling the EGR (sob story here). What else could be causing this. I've had various people suggest to me that it might be the fuel pump relay, idle air control, throttle position sensor, and other assorted things. What do you guys think?

Please help.

 

[rubydist]

I would suggest that you put a meter on the tps and see if it has a nice smooth resistance change as you rotate the throttle plate, or if it has dead spots.

Did you do the koer test also? What were those results?

 

[Joe_Cool]

I would suggest that you put a meter on the tps and see if it has a nice smooth resistance change as you rotate the throttle plate, or if it has dead spots.

Did you do the koer test also? What were those results?

The EGR was the only code I got on the KOER (other than the user error code, since I didn't do the gas pedal and O/D button lol).

Replaced it and the plugs and wires today, and it SEEMS to be running like brand new. Long test drive coming this afternoon.

 

[Joe_Cool]

So it appears the problem was the plugs and wires. It drives really well now. It started overheating yesterday afternoon, but a new thermostat seems to have fixed that.

And now the CEL comes on once in a while for about 10 seconds. lol Back under the hood tonight.

 

[Joe_Cool]

Just ran the codes, and it's still giving a 332 (EGR opening not detected, according to the chart on shotimes). I just replaced the EGR. Other than the little vacuum tube I didn't see anything that should connect to it... is there a sensor someplace that I need to replace?

 

[rubydist]

The 332 code will cause the check engine light to come on.

There is no other sensor to replace, but the common problem is not the egr valve itself, but rather the small passages in the sensor tube and in the intake that get clogged up with carbon junk - those will need to be cleaned.