2004 3.8L Struggling W/ P0175 Code For Months

SVT232V6

Member
don't recall...did you change the plug wires?

New

Spark Plugs - Need to check
Spark Plug Wires - StandardMP 3340
Ignition Coil - StandardMP FD498T
HO2 Sensor(B2S1) - Motorcraft DY1039
HO2 Sensor(B2S2) - Denso 2344160
Fuel Pump - Airtex E2301M
EGR Pressure Sensor - Motorcraft DPFE15
MAF Sensor - StandardMP MAS0118

Another video I recorded a month ago.
 
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Serpent

Active Member
ok, check the plugs then for sure and depending on what you find, take pictures of what they look like.
 

SVT232V6

Member
ok, check the plugs then for sure and depending on what you find, take pictures of what they look like.

I can take some pics tomorrow. I ended up swapping the fuel injectors and rail with hose from the silver 01 we brought home just because. Rechecked the scanner data and things are way different? Top picture was before the replacement. Bottom 2 pics are after.
 

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SVT232V6

Member
how does it run?

It was running great on cold start up. Isles good until about a minute and a half to two minutes until the popping starts. Idle then gets progressively worse until it’s constantly popping. Car shakes in time with the popping noise. It’s like a misfire, but I’m not sure why it would run good cold then get worse when warming up until it’s constant. It runs good under load, just can’t idle. My fuel trims and values changed completely after swapping he Fuel Rail Pressure Sensor over from the 01, so Im going to run it today after work and see if that was the problem. Wondering if the factory unit and the replacement I bought were maybe both bad? I’m open to tests, ideas, suggestions of things to try. Don’t know everything but willing to learn and try new things!
 

SVT232V6

Member
Also another symptom I noticed that’s different from my other cars is that on start up, there is something like a hiccup. Car will start up for a second, then stop for another second, then start and co to he running. It’s in the longer video that I posted. Don’t know if that’s related or not?
 

Sam36

Active Member
Compression Test Results

Passenger Side
1 - 145
2 - 146
3 - 145

Driver Side
4 - 134
5 - 142
6 - 142

Cylinder 4 is a little low compared to the other 5. There was some gas in that cylinder while doing the compression test that I didn’t experience with any of the other cylinders. I’m going to retry cylinder 4 tomorrow after I let it air out overnight. Leaking injector? Too much fuel in that cylinder maybe?

Having around 150 on a car close to 200k miles is about normal imo. So congratulations!

As far as fuel, if you didn't pull the injector or fuel relay during all the cranking for the compression test, then you'll probably have a bunch of fuel in there. Most people pull the wire going to the coil just so the car won't start, not sure if you did that or not.
 

Sam36

Active Member
Here’s a video of what it sounds like. Popping starts around 1:26.


So that is pretty interesting. First off, I see when you get the ignition on, the gauges do a sweep. That normally only happens when the computer as been reset. Did you perhaps have the battery out before then? If you get getting a gauge sweet on every start then there is some other issues...

You mentioned the little surge or dip in rpms right at start, yea mine does that too. Probably normal, especially if the computer was just reset.

Now around the 40 second mark, I hear a couple of faint pops. Mine actually does that too on cold starts, especially if it sat for a few days. But it is not a constant popping, several a minute maybe. But it goes away once it warms up. And even around the 1:30 mark in the video, that still sounds pretty familiar. But around 2:20, yea that is not sounding too familiar.

And that brings us to the 2:35 mark where you rev it just a bit. I hear a good 'thump thump thump' sound as the rpms fall. That really sounds like a cylinder not firing. So lets figure out which one..

We'll need to have the car running, and pull each spark plug wire out of the coil one by one. It can be hard to get the wires out of the coil since they are clamped in those little sockets. You might be able to get each plug slightly unhooked from the socket (so it will be easier to fully unplug) and then start the car that way. But you'll still probably get zapped either way....

So start with the #1, which is apparently on the bottom right on the coil. With the car running (and hopefully popping), pull the #1 wire off the coil. Note the affect it has on the RPM and overall idle quality and put the wire back on. Next, up do the same for #2. And 3,4, etc. You'll find one wire (hopefully) that when removed, the car will not idle that much worse, and that will be our "bad cylinder" or maybe in this case, just a "weak cylinder".

So now that we know which cylinder is weak, we can investigate why. You've already swapped injectors and stuff, so probably not that... Either going to be a wire or plug. You can take advantage of the fact that the coil fires in "pairs" once per revolution. 1 and 5, 2 and 6, followed by 3 and 4. Or at least I think... So if indeed cylinder #4 is the weak one, try plugging it into the socket right below it on the coil which would be #3 (so just swap wires 3 and 4 on the coil). From there you can re-do your test. If the coil is bad, #3 will now be the 'weak cylinder' otherwise if its a bad wire there will be no change in the test results.

I don't know if this is the right diagram, so make sure:



Though it would be weird if you had a bad plug or wire since you just replaced those... Probably more likely a coil problem, especially considering the quality of parts these days... Other than that, getting really low on ideas...
 

SVT232V6

Member
So I had some new codes come up

P0304 Misfire Cylinder 4 (Intermittent)
P0316 Misfire Detected on Startup (First 1000 Revolutions)
P0175 System Too Rich Bank 2 (Repeat)
P2195 O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1

I need a cigarette...and I don’t even smoke!
 

SVT232V6

Member
So that is pretty interesting. First off, I see when you get the ignition on, the gauges do a sweep. That normally only happens when the computer as been reset. Did you perhaps have the battery out before then? If you get getting a gauge sweet on every start then there is some other issues...

You mentioned the little surge or dip in rpms right at start, yea mine does that too. Probably normal, especially if the computer was just reset.

Now around the 40 second mark, I hear a couple of faint pops. Mine actually does that too on cold starts, especially if it sat for a few days. But it is not a constant popping, several a minute maybe. But it goes away once it warms up. And even around the 1:30 mark in the video, that still sounds pretty familiar. But around 2:20, yea that is not sounding too familiar.

And that brings us to the 2:35 mark where you rev it just a bit. I hear a good 'thump thump thump' sound as the rpms fall. That really sounds like a cylinder not firing. So lets figure out which one..

We'll need to have the car running, and pull each spark plug wire out of the coil one by one. It can be hard to get the wires out of the coil since they are clamped in those little sockets. You might be able to get each plug slightly unhooked from the socket (so it will be easier to fully unplug) and then start the car that way. But you'll still probably get zapped either way....

So start with the #1, which is apparently on the bottom right on the coil. With the car running (and hopefully popping), pull the #1 wire off the coil. Note the affect it has on the RPM and overall idle quality and put the wire back on. Next, up do the same for #2. And 3,4, etc. You'll find one wire (hopefully) that when removed, the car will not idle that much worse, and that will be our "bad cylinder" or maybe in this case, just a "weak cylinder".

So now that we know which cylinder is weak, we can investigate why. You've already swapped injectors and stuff, so probably not that... Either going to be a wire or plug. You can take advantage of the fact that the coil fires in "pairs" once per revolution. 1 and 5, 2 and 6, followed by 3 and 4. Or at least I think... So if indeed cylinder #4 is the weak one, try plugging it into the socket right below it on the coil which would be #3 (so just swap wires 3 and 4 on the coil). From there you can re-do your test. If the coil is bad, #3 will now be the 'weak cylinder' otherwise if its a bad wire there will be no change in the test results.

I don't know if this is the right diagram, so make sure:



Though it would be weird if you had a bad plug or wire since you just replaced those... Probably more likely a coil problem, especially considering the quality of parts these days... Other than that, getting really low on ideas...

The problem is a misfire on cylinder 4. I’m now having a confirmed trouble code P0304. Before it was intermittent, came and went and drivability isn’t affected while driving. Car definitely has power accelerating up hills and at WOT. I was experimenting before I saw your post, so forgive me for maybe not following your instructions to the letter..

While the car was idling, I pulled the spark plug wire from ignition coil socket number 4(bottom row, far right). The idle stayed basically the same. For further testing, I turned off the engine and unplugged the number 4 fuel injector(driver side, furthest towards the radiator). Started the car with no change in idle. Plugged the injector pigtail bacn into the injector and the idle went up for a few seconds before reverting back to normal missing idle.

I agree! Running out of options here.. I didn’t think to swap spark plug wires at the coil between sister cylinders, will try that tomorrow.

ALSO! I redid the compression test on Bank 2 after seeing the misfire codes just to recheck for checkings sake. Cylinder 4 actually is 145. I must not have done it correctly the first time.
 

Sam36

Active Member
spark plugs next.

That plug doesn't look bad. Looks like new other than being dirty! I'm still putting my money on a bad coil was replaced with a bad coil. If you are short on cash, you might be able to get by with buying a single iridium plug for #4 (like NGK TR55IX). That is what I run all the way around. Iridium has a smaller electrode and takes less voltage to fire so a "bad" coil might still work on it. But certainly check your wires before spending money.

And speaking of checking stuff, if you have an ohm meter, you can check the coil too. Here's some photos from the ford service manual:

20190205_124435.jpg 20190205_124448.jpg 20190205_124612.jpg 20190205_134811.jpg 20190205_134828.jpg 20190205_134845.jpg

Looks like for the primary coil, you measure on the wiring harness plug on the coil, the far left pin is for power, and the other three pins are to the primary coils. So measure ohms between pin 1 - pin 2, pin 1 - pin 3, and pin 1 - pin 4. Should be around 5 ohms.

Then for secondary coil, measure between each plug wire socket (vertically). Should be between 10,000-15,000 ohms. Though the sad thing is, I've seen coils measure out fine but when replaced, car ran like new... So checking ohms only seems to show severe defects.
 
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Sam36

Active Member
ALSO! I redid the compression test on Bank 2 after seeing the misfire codes just to recheck for checkings sake. Cylinder 4 actually is 145. I must not have done it correctly the first time.

Pressures can change from time to time. Temperature plays a factor as well as having rings simply move around and line up differently. Having excessive gas go through a cylinder will wash out any oil on the rings which will allow air to flow through them easier as well. The point one looks for is evenness of all the pressures. If everything measured 150 but one was measuring 100, that would be an issue. A variance of 10% or so from the highest to the lowest is generally considered "good".
 

6 Shooter

Well-Known Member
Not sure if you mentioned the number of miles on this motor. So, if the motor has not had any major upgrades or renovations, a high mileage motor may have an issue with a stretched timing chain or weak and worn tensioner which would require pulling the radiator, the flywheel pulley, the oil pump, and the front timing cover for an inspection. In addition, would need to pull the spark plugs and get the motor set on TDC #1 cylinder. A weak/worn timing chain tensioner or loose/worn timing chain would cause the cam timing to move out of alignment with the crank which would contribute to the engine popping noise.
 

SVT232V6

Member
That plug doesn't look bad. Looks like new other than being dirty! I'm still putting my money on a bad coil was replaced with a bad coil. If you are short on cash, you might be able to get by with buying a single iridium plug for #4 (like NGK TR55IX). That is what I run all the way around. Iridium has a smaller electrode and takes less voltage to fire so a "bad" coil might still work on it. But certainly check your wires before spending money.

And speaking of checking stuff, if you have an ohm meter, you can check the coil too. Here's some photos from the ford service manual:

View attachment 164288 View attachment 164289 View attachment 164290 View attachment 164291 View attachment 164292 View attachment 164293

Looks like for the primary coil, you measure on the wiring harness plug on the coil, the far left pin is for power, and the other three pins are to the primary coils. So measure ohms between pin 1 - pin 2, pin 1 - pin 3, and pin 1 - pin 4. Should be around 5 ohms.

Then for secondary coil, measure between each plug wire socket (vertically). Should be between 10,000-15,000 ohms. Though the sad thing is, I've seen coils measure out fine but when replaced, car ran like new... So checking ohms only seems to show severe defects.

That’s because it is lol The plugs are Autolites. Those are what I have in my Mach1. Going on 5 years now with no issues whatsoever. Excellent plug. Well I do have 3 different coil packs to play with and 5 extra spark plug wires. I’ll test them all tomorrow and see. Couldn’t do anything the last two days. Worked a 16 yesterday and had firearms/use of force training in Hilo today after 4 hours of sleep!

I think I do. I will test the parts and report back.

Pressures can change from time to time. Temperature plays a factor as well as having rings simply move around and line up differently. Having excessive gas go through a cylinder will wash out any oil on the rings which will allow air to flow through them easier as well. The point one looks for is evenness of all the pressures. If everything measured 150 but one was measuring 100, that would be an issue. A variance of 10% or so from the highest to the lowest is generally considered "good".

I should be good on compression then. I have ~145 across all 6 cylinders at 176K miles.

Not sure if you mentioned the number of miles on this motor. So, if the motor has not had any major upgrades or renovations, a high mileage motor may have an issue with a stretched timing chain or weak and worn tensioner which would require pulling the radiator, the flywheel pulley, the oil pump, and the front timing cover for an inspection. In addition, would need to pull the spark plugs and get the motor set on TDC #1 cylinder. A weak/worn timing chain tensioner or loose/worn timing chain would cause the cam timing to move out of alignment with the crank which would contribute to the engine popping noise.

It has 176,2xx miles. I will keep that in mind, never did a timing chain job on the car yet. Would be a great learning experience.
 
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