Sunday my truck began to sputter at idol while at a light and continued when parked. My first assumption was another coil pack has gone out. Went to autoparts store to get a new one and run the codes to tell me which cylinder it was. Code P0357 came up referring to cylinder G which seemed odd to me as it usually gives me a number rather than a letter. Bought the coil pack and went home to swap it out. Replaced the coil and with no change in the idol I googled the code. I have now replaced the coil, inspected the plug and wires around the plug and now I am at a loss of what to do next.

There is only a rough idol, no hesitation when driving or accelerating. Along with that, I've notice that if I'm going between 30-50 and take my foot off the gas it doesn't slow down, it's as though the cruise control is on... After a few miles on the highway and come to a stop, the RPMs are around 1k for about 30 seconds then drops to almost stall before catching itself and begins to sputter.

Any thoughts would be greatly appreciated.

 

Code 0357 is cylinder 7 or cylinder G.
If you changed #7 and still have the fault, the harness is open back to the computer or the computer cylinder 7 coil driver is faulty.
Cylinder 7 is next to the last one toward the rear on the driver side.
If it turns out to be the computer, it has to be replaced, and reprogrammed with your 2 keys.
The new computer needs the programing due to the PATS and Dash compatibility that must communicate with each other.
This is dealer work.
Good luck.

 

Make sure the connector for the coil is ok. The wires can break at the connector end. Also clear the code and see if it comes back right away. If so you have a wiring or computer problem. Also make sure the connector is seated properly. You can also swap coils with a good cylinder just to rule out a defective part.

 

Sorry for late response, been one of those days at work. Thank you for your replies.

On my way home today it only sputtered once while stopped at a light but instead held itself around 1k rpms and would jump to 1500 if put into nutral. I hope it's not the computer, not a bill I can handle right now lol. I will stop by the auto parts store and have them clear the codes and I'll recheck the connecting plug.

 

Ended up replacing the harness plug for #7. Saw somewhere to disconnect the battery for 30 minutes and then let it run for a good bit, so I did that. Now original code is gone but have P0171 & P0174. Read most commonly they are vacuum issues. Looked through the motor with no visual luck finding anything. Spayed carb spray around intake manifold as suggested by google finds and still nothing. Finally I used my hand to follow every hose I could see in hopes to feel a fault. After 10 minutes I found it. The 90 elbow from the PCV to the far backside of the intake had a good sized hole in it. Taped it till I can get back to the store.

 

Well done as they say in England.
Some comment; you don't need to remove the battery for 30 min to reset a code. 30 to 45 seconds in enough.
This triggers all diagnostics to be run from scratch.
The Ell behind the intake gets soft from the crank case fumes, then the intake vac and heat sucks a hole.
The result is the fuel tables shift out of limits setting both codes because the point of the leak is common to all cylinders.
The Ox sensors detect the excess Ox for both banks.
Thanks for reporting your success. It will help, others.
Good luck.

 

Good to know about the battery.

That was my biggest problem when searching the net, plenty of troubleshooting methods but no successful results as no one posted their final solution.

The hole in the elbow is taped closed but from the heat it has collapsed atleast half way so there is still restrictions passing so I am hoping with new elbow I can finish this headache.

 

I just went through this with my 98 expedition. Google must have missed my P0354 code thread on the Expedition enthusiasts forum. I went through everything. Ended up replacing the connector and that fixed it. Also fixed my rear wiper somehow. The first test is to pull the connector to see if you still have the missfire with it running. Before buying a coil rent to own a set of noid lights from Oreallys and the GM pfi light is the one that fits these connectors and not the ford one. Look for steady flashing for a while to show it works. You can check all connectors including the injectors with the noid light. The coils all carry some resistance, somewhere around 115k if I remember correctly, which you can test with a multi-meter, and if it shows an open or a dead short you know it is bad but the ohms test may not find all defects. You can check injectors to see (they have a different resistance reading) if they have an open or dead short as well although the P035x codes have nothing to do with injectors. I would swap the coil with another that is in front and easy to get to and see if that fixes it before spending money on a new coil pack. I might add the stealerships usually replace the coil pack to say they did something when it might just be the boot or connector inside. I use a good dab of dielectric grease on the end of the boot where the plug goes and in the coil electrical connector. I also coat the boot on the outside on the slim part and particularly around the seal area of the cylinder to avoid it sticking so bad later on. Also do not use anti-seize on the spark plugs (motorcraft sp-479) but do use anti-seize on all other bolts such as the 7mm bolt holding the COP as it will also lube the threads and hopefully avoid future threading problems.

It is very rare to have the pcm/gem go bad on these things. In the process of checking everything I manipulated that coil connector many times. I get the test light to ground to light up on the left side 12 volt wire in the connector. I checked it and the pulse-ground wire on the right for continuity going all the way to the connector plugs on the firewall and the connector plug on the pcm. What I figured out is that I then had intermittant operation which must have been a broken wire in the coil connector as a new one fixed everything. Because I was dealing with the connector on plug #4 under the firewall of expeditions I spliced in a new one with the pulse-ground wire spliced in at the pcm connector and the hot wire spliced in at the 42 pin connector at the firewall. The hot wire coming from that connector actually fires the entire bank of cylinders so I spliced in as opposed to cutting it off. I spliced in at the pcm with the pulse-ground wire as well which left the old connector hot.

The coils are continuously fed voltage with the hot wire and the pcm pulses in the proper firing order the pulse ground wire and the process of opening and closing the ground on the coil causes it to fire. Typically you would think that you send/pulse voltage to something when you want it to go off but the opposite must work better.

My 2000 F150 has thrown the 171 and 174 codes for years. It has a broken off nut on the passenger side rear bolt of the exhaust manifold. Makes a little exhaust noise there. I've tried welding a nut but it won't hold to unscrew the stud. One of these days I will pull the manifold and fix it. It runs great during the summer but in the dead of winter it rough idles when it is cold which goes away after it warms up. I assume the cold causes the gap in the manifold to open up more causing the rough idle. As I understand it, the 171 and 174 codes cause the computer to read high on O2 so it shoots in more fuel to compensate and enriches the mixture. Fixing it may get me better mileage as well.

 

an easier fix might be to install an engine heater, something to keep it warm when not in use. Many with diesels do this. good luck