96 Crown Vic/cutting out

My brother has a 96 that runs great, but between 35 to 45 mph, under light load at low rpm, the engine seems to cut out a little bit. I am not a Ford man but I know on others a bad plug wire can cause this. Under heavy acceleration it shifts and runs great. Any one have any idea's, and what a normal resistance reading is for a plug wire(does it depend on the length of the plug wire)?

Also had a problem with the heater not getting very hot. Replaced the thermostat, which helped the problem somewhat, but not completly. One heater hose is hot and the other fairly warm, but I wonder if the heater core is getting dirty? Fan only works on low and high. Can it be just the switch for the fan, or is there another relay I can look for?

Thanks in advance.

The "cutting out" sounds like torque converter clutch chatter. I'll bet if he turns the O/D off at lower speeds, it doesn't happen. The fan switch issue sounds like the blower resistor is fried-at least that's been the case on the 50 or so Crown Vic's I've seen this problem on. It's a little tough to access too, but worth it to save some wear/tear on the blower motor. As far as the lack of heat, a couple factors come into play here. The temp gauge should be at almost exactly half way when the engine is fully warmed up. If you didn't install the OEM 195 degree thermo, it won't get there. The one hot hose and one warm one simply means the heater core is working properly-as heated coolant passes thru, heat transfers into the air forced thru the heater core and the coolant leaving the heater core is cooler. It's basically a smaller radiator. With the fan running on high, it will cool it down even more.

Sparkplug wire resistance should be VERY close to 1000 ohms/ft. At 1500 ohms/ft they need to be replaced. Most often they will either be good or junk.

The issue you describe *could* be EGR related, but you should get a code for that. I do agree that if it is bucking/missing plugs and wires would be my first suspects, but do not overlook a dirty MAF sensor. You can inspect and clean it by following the directions here: www.crownvic.net/cleanmaf.html

Now, if you do think that the engine is misfiring you need to disprove the torque converter as the cause. When the TC "shudders" it feels EXACLTY like going over "rumble strips", that is like a fast vibration. A true engine misfire is MUCH slower and no anywhere as consistant and softer. In a way like being tugged by a slackened rope... tug, tug.

My 1996 LX has similar heater issue except the blower speed control is ok. The gage goes halfway up, it has a new ford thermostat, it defrosts, though maybe a bit slow. Yet it doesn't feel that warm. It had a new blower motor, heater core, and air blend motor in the past, no change.
I am wondering if they just don't heat that well??

Wheel7

I have a 92 gm and 94 cv and both heat up great and fairly fast. After about 15 - 20 minutes of driving the heat seems at it's peek at which point I tend to turn the heat down, as I can feel my gas foot getting hot.

My 1996 LX has similar heater issue except the blower speed control is ok. The gage goes halfway up, it has a new ford thermostat, it defrosts, though maybe a bit slow. Yet it doesn't feel that warm. It had a new blower motor, heater core, and air blend motor in the past, no change.
I am wondering if they just don't heat that well??

Wheel7

Sparkplug wire resistance should be VERY close to 1000 ohms/ft. At 1500 ohms/ft they need to be replaced. Most often they will either be good or junk.

The issue you describe *could* be EGR related, but you should get a code for that. I do agree that if it is bucking/missing plugs and wires would be my first suspects, but do not overlook a dirty MAF sensor. You can inspect and clean it by following the directions here: www.crownvic.net/cleanmaf.html

Now, if you do think that the engine is misfiring you need to disprove the torque converter as the cause. When the TC "shudders" it feels EXACLTY like going over "rumble strips", that is like a fast vibration. A true engine misfire is MUCH slower and no anywhere as consistant and softer. In a way like being tugged by a slackened rope... tug, tug.

Thanks for all the great replies folks.
Can anyone tell me where to locate the blower motor resistor? I don't have a service manual for this car.

As for the shudder, I do think it is a plug wire but will test them first.
It certainly does not feel like the TC, and this car only has around 80,000 miles on her.

The blower motor resistor is located behind the passenger side valve cover. It is about 2"x3" & bolts into the plastic a/c/heat duct with two screws with 8mm hex heads. If you replace it, be careful not to break the electrical connector. Check out the connector good too-if it's burned at all, get a new one with wires from ford or a good one from a junkyard.

If the car has 80,000 miles, it probably has original plugs & wires, so it would be high time for new OEM double platinum plugs anyway. If the wires are original (you can tell by the cylinder numbers on them), replace them too. Make sure you put the good OEM ones on there-the only others I have had any luck with are the NAPA Belden Premium wires, but they still don't last quite as long & cost almost as much. Make sure plugs are properly gapped & make sure to use a little bit of dilectric silicone grease in the wire ends to ease installation/removal. And FYI, 9 years/80,000 miles is not too early for the TCC to chatter/shudder, especially if the tranny has not been kept maintained.

The blower motor resistor is located behind the passenger side valve cover. It is about 2"x3" & bolts into the plastic a/c/heat duct with two screws with 8mm hex heads. If you replace it, be careful not to break the electrical connector. Check out the connector good too-if it's burned at all, get a new one with wires from ford or a good one from a junkyard.

If the car has 80,000 miles, it probably has original plugs & wires, so it would be high time for new OEM double platinum plugs anyway. If the wires are original (you can tell by the cylinder numbers on them), replace them too. Make sure you put the good OEM ones on there-the only others I have had any luck with are the NAPA Belden Premium wires, but they still don't last quite as long & cost almost as much. Make sure plugs are properly gapped & make sure to use a little bit of dilectric silicone grease in the wire ends to ease installation/removal. And FYI, 9 years/80,000 miles is not too early for the TCC to chatter/shudder, especially if the tranny has not been kept maintained.

Thanks for the info, much appreciated.
Will see what I find out regarding the shuttet.