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Discussion Starter · #1 ·
I have an 88 Ford Taurus that just started acting up again after a couple years, and it only seems to develop an issue when it's cold out. The first thing I noticed when driving to work the other day is that you could feel the car starting to hiccup at around 50 mph. It quit doing that for a couple days then it came back. It was warmer outside the other day and I went to start it so I could move it and it starts, but with a low rough idle. If you gas it a little it starts to smooth out eventually. I was starting to think maybe fuel pump, but you can hear it pump the system up fine. But I am also not sure what the operating pressure of that system is. I checked the pressure the other day and it was reading low 30's, around 32 or 33 psi. It has a fairly new throttle position sensor on it, and I replaced the MAP sensor a couple years ago (they do not run at all without those working correctly). What should I be looking for here?
 

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What engine? 3.0 or 3.8?

Fuel pressure when idling should be low 30's. System pressurized engine off (i.e., after a few key on / key off cycles) should be 39 psi.

CEL on? Even if it isnt, check for any stored codes.

When were the plugs, wires, cap, rotor replaced?

Your car as the infamous Ford PIP sensor inside the distributor and TFI ignition module on the outside of the distributor that are known for intermittent issues to outright failure. Sometimes they set a code, sometimes they dont.

Check the hose going to the PFE sensor to be sure it is connected, not dry rotted, etc. Also check for other rotten vacuum hoses.
 
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Discussion Starter · #3 ·
I forgot to mention 3.0 in the thread, my bad. So it looks like my fuel pressure is good. No Check Engine Light, as far as checking for codes I will have to find someone with a reader. I replaced the plug wires maybe 2 or 3 years ago, and I believe I did the plugs right around the same time. I replaced components in the distributor about 7 years ago as the PIP sensor was going bad, and I replaced the TFI module at the same time. Cap and rotor have been replaced since then as well. I will have to go over the hoses again, I didn't find anything the last time I went over them, but I could have missed something. The one thing it has done for a long time is on a cold start either during the summer or winter is that it chugs on me for a few seconds, but does not do it through out the rest of the day.
 

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Discussion Starter · #4 ·
What engine? 3.0 or 3.8?

Fuel pressure when idling should be low 30's. System pressurized engine off (i.e., after a few key on / key off cycles) should be 39 psi.

CEL on? Even if it isnt, check for any stored codes.

When were the plugs, wires, cap, rotor replaced?

Your car as the infamous Ford PIP sensor inside the distributor and TFI ignition module on the outside of the distributor that are known for intermittent issues to outright failure. Sometimes they set a code, sometimes they dont.

Check the hose going to the PFE sensor to be sure it is connected, not dry rotted, etc. Also check for other rotten vacuum hoses.
.
 

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Discussion Starter · #5 ·
What engine? 3.0 or 3.8?

Fuel pressure when idling should be low 30's. System pressurized engine off (i.e., after a few key on / key off cycles) should be 39 psi.

CEL on? Even if it isnt, check for any stored codes.

When were the plugs, wires, cap, rotor replaced?

Your car as the infamous Ford PIP sensor inside the distributor and TFI ignition module on the outside of the distributor that are known for intermittent issues to outright failure. Sometimes they set a code, sometimes they dont.

Check the hose going to the PFE sensor to be sure it is connected, not dry rotted, etc. Also check for other rotten vacuum hoses.
I went and bought a code reader for this car the other day and ran it, and it came back with a code 33 which appears to be an EGR issue. Now is this going to be a problem with the valve, or is this a problem with the EGR sensor? And would this be causing the stumbling problem on start up, and the hiccupping while driving down the road? I've gone over the tubes and hoses and everything looks good.
 

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You can look at the output voltage between the SIG RETURN wire and PFE output to PCM wire. If I remember correctly (old guy memory) output voltage drops as PFE pressure increases, such as when engine is under load or revving in neutral or park. Voltage varies between around 1 V to 4 or so V. Also check between SIG RETRUN (likely black with white stripe) and VREF (likely white / black stripe) to be sure you have 5 V. If output voltage stays constant under different load conditions, either PFE is dead, hose is damaged / split, of pressure pickup on the exhaust is plugged with crap (unlikely but possible).
 
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Discussion Starter · #10 ·
You can look at the output voltage between the SIG RETURN wire and PFE output to PCM wire. If I remember correctly (old guy memory) output voltage drops as PFE pressure increases, such as when engine is under load or revving in neutral or park. Voltage varies between around 1 V to 4 or so V. Also check between SIG RETRUN (likely black with white stripe) and VREF (likely white / black stripe) to be sure you have 5 V. If output voltage stays constant under different load conditions, either PFE is dead, hose is damaged / split, of pressure pickup on the exhaust is plugged with crap (unlikely but possible).
Jeff, do you have any idea what kind of material the rubber hose is made of that attaches to the PFE sensor? The hose is only 3 or 4 inches long, but it should be able to handle some
You can look at the output voltage between the SIG RETURN wire and PFE output to PCM wire. If I remember correctly (old guy memory) output voltage drops as PFE pressure increases, such as when engine is under load or revving in neutral or park. Voltage varies between around 1 V to 4 or so V. Also check between SIG RETRUN (likely black with white stripe) and VREF (likely white / black stripe) to be sure you have 5 V. If output voltage stays constant under different load conditions, either PFE is dead, hose is damaged / split, of pressure pickup on the exhaust is plugged with crap (unlikely but possible).
Jeff, do you have any idea what kind of material the rubber hose is made of that attaches to the PFE sensor? The hose is only 3 or 4 inches long, but it should be able to handle some heat as well because of the exhaust gases going through the EGR tube.
 

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High temperature Silicone hose.
 

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Discussion Starter · #12 ·
High temperature Silicone hose.
One other question I should have included, why do all the replacement parts say w/ California emissions? Do the replacement parts cover both? I usually buy Standard Motor Products, and both their website and the suppliers sites say that. Do they cover both Federal and California emissions?
 

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Not sure, but I doubt the PFE would be any different for Cali emissions than for 49 state emissions.
 

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Discussion Starter · #14 ·
Not sure, but I doubt the PFE would be any different for Cali emissions than for 49 state emissions.
I went ahead and got both the EGR valve and the DPFE sensor since the price was decent on both items and replaced them. I will check this weekend to see if it clears that 33 code. I did notice some difference on start up, however it was still running like it had a miss fire of some sort. What I found since it was getting dark out is that some of the ignition wires were basically leaking. I saw spark jumping from the coil wire to a bracket, and also a couple of the plug wires were doing the same thing. These wires are only 4 or 5 years old with maybe 20k miles on them. I guess I will be replacing them as well to see if that clears up the rest. Also is it common for the 3.0 to develop piston slap when the engine is cold. It goes away once it's warmed up, and the car has 177k miles on it.
 

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Use the correct Motorcraft wires, not cheap junk from the discount parts store.
 
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^+1 on opting for Motorcraft parts. Did so on my 94 3.8L 90K mile scheduled maintenance & was favorably impressed with the distributor cap, rotor, wires & the plugs Quality. All nice pieces of work. I opted for the fine wire iridium enhanced center electrode, with platinum pad side wire ground lug plugs, as they'll retain the specified spark gap longer, make a hotter spark kernel that can help get us going on those cold winter starts & are the correct heat range. I enjoy quicker year round starts with the fine wire plugs, now in All my vehicles. Battery, Starter & Engine appreciate the quicker starts too!!!!
Also consider as I did, to spread a thin film of a good quality di-electric grease, like Permatex / Loctite, Dow-Corning, GE, onto the plugs External ceramic insulators & inside the plugs boots & spray the Inside of the distributor cap with CRC heavy duty silicone spray, so to prevent flash-over on those damp dewy starts, or rainy day drives.

More thoughts for consideration, let us know how it goes.
 

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^+1 on opting for Motorcraft parts. Did so on my 94 3.8L 90K mile scheduled maintenance & was favorably impressed with the distributor cap, rotor, wires & the plugs Quality. All nice pieces of work. I opted for the fine wire iridium enhanced center electrode, with platinum pad side wire ground lug plugs, as they'll retain the specified spark gap longer, make a hotter spark kernel that can help get us going on those cold winter starts & are the correct heat range. I enjoy quicker year round starts with the fine wire plugs, now in All my vehicles. Battery, Starter & Engine appreciate the quicker starts too!!!!
Also consider as I did, to spread a thin film of a good quality di-electric grease, like Permatex / Loctite, Dow-Corning, GE, onto the plugs External ceramic insulators & inside the plugs boots & spray the Inside of the distributor cap with CRC heavy duty silicone spray, so to prevent flash-over on those damp dewy starts, or rainy day drives.

More thoughts for consideration, let us know how it goes.
You do well to buy OE parts but inspect carefully. Pic of Autolite plugs I returned. Store likely put them back on the shelf and sold them to someone else. Doubt MC would let this kind of thing pass. But inspect, inspect and repeat. My op.
-chart-
 

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Discussion Starter · #18 ·
^+1 on opting for Motorcraft parts. Did so on my 94 3.8L 90K mile scheduled maintenance & was favorably impressed with the distributor cap, rotor, wires & the plugs Quality. All nice pieces of work. I opted for the fine wire iridium enhanced center electrode, with platinum pad side wire ground lug plugs, as they'll retain the specified spark gap longer, make a hotter spark kernel that can help get us going on those cold winter starts & are the correct heat range. I enjoy quicker year round starts with the fine wire plugs, now in All my vehicles. Battery, Starter & Engine appreciate the quicker starts too!!!!
Also consider as I did, to spread a thin film of a good quality di-electric grease, like Permatex / Loctite, Dow-Corning, GE, onto the plugs External ceramic insulators & inside the plugs boots & spray the Inside of the distributor cap with CRC heavy duty silicone spray, so to prevent flash-over on those damp dewy starts, or rainy day drives.

More thoughts for consideration, let us know how it goes.
I received my Motorcraft wire set yesterday and noticed one of the boots is a light grey color and the rest are black. Is there something that I should be aware of on that?
 

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I doubt the boot color is anything to worry about.
 

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Is the different color boot on the distributor cap to coil wire, or on a plug wire?
 
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