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Hello,
I posted this to the last hangout –
Hello Eric. I really appreciate your videos and you’ve saved me thousands of dollars with your videos over three cars. I have a 2003 Ford Focus SE with 95k miles on it, and I have a P0420, Catalyst System Efficiency Below Threshold (Bank 1). I used your diagnostic test with an infrared thermometer and checking the O2 sensor live data, and both indicate the cat is bad. I know you’ve stated previously that catalytic converters don’t go bad without something else making them go bad, like burning oil. This engine gets regular maintenance and the only symptom this car exhibits is a strong vibration across all RPMs that occurs standing or driving. With this scenario, what are the things that I should be checking for before replacing the cat? I’d hate to put a new one on just to cause it to get toasted shortly down the road. Thanks again for your videos and work.
First of all, thank you very much for your response!
I performed the power balance test and every cylinder dropped the RPM about 200 or so, so they all seem to be contributing. Should I test the engine further? I can do a compression test easy enough (parts store down the road will let me borrow their tester) but I don’t have easy access to air for say a leak down test.
I also did some reading online and discovered a pattern problem with engine mounts causing vibration. The TSB was easy enough to check (there’s no debris in the mount underneath). The two rubber mounts look fine, and the rubber in them is intact. I have no idea how to properly inspect the hydraulic mount, It looks intact and doesn’t seem to have leaked, sooo… :S
Following the engine performance videos, I found corrosion inside the spark plug wells and on the plugs, and a crack in one of the plug wires which probably let water in. I’m replacing those in short order today. I’ve already sanity checked the air filter (replaced recently), oil (1500 miles ago), and want to make sure I’m on the right track here.
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The vehicle has not overheated to my knowledge. I was entertaining the idea of block testing based on Evil-i’s prior suggestion to consider a wrong installed head gasket.
I have seen the performance issues article. Here’s where my vehicle sits right now – I’ve since checked the plugs and wires (replaced actually with Motorcraft everything, the wires were damaged), fuel filter/air filter was 10k ago, oil level is good, looks normal (I’ve not sent a sample off for testing). The only symptoms I have are the P0420 and engine vibration. Further testing of the cat shows the P0420 is genuinely the cat and not an O2 sensor. Power balance test suggests no misfire. I can’t find any vacuum leaks (although, if there’s any not-so-obvious spots to look I might be missing). Fuel pressure is not a topic that I’ve visited yet. It starts fine after one or two cranks every time. Engine timing has not been checked yet – has a service coming in about 20k miles.
[quote=”jdphenix” post=141359]Well, the first tester I thought might have been suspect. There was a little bit of damage to the o-ring around the adapter for the plug threads. It might have ended up mattering more than I thought.
Here’s the results with the 2nd tester:
Cyl Dry (psi) Wet (psi) Cyl 1 171 173 Cyl 2 161 170 Cyl 3 165 181 Cyl 4 169 182 Is the fact that the power balance test I did suggests every piston is equally contributing diagnostically sound to call this engine healthy?[/quote]
The power balance test is a diagnostic test for a fuel delivery issue. Since you report hearing an even drop of RPM across all injectors, I’d say there is more than likely no issue with fuel delivery at the injectors anyway.
Based on these new compression data, I’d say your engine is in seemingly good health, at this point.Yes, a high quality compression tester is very important for collecting valid data. I like MAC (vs. Actron) compression testers (I have used both).
I am leaning more towards that hydraulic mount you referred to earlier in the post as being the culprit of your engine vibration since we have eliminated some of the other possible causes. However, I am still curious as to what design of ignition system Ford used in your vehicle. Since you have replaced the plugs and wires, you should have good spark unless there is an issue at the primary side of the ignition system (i.e. coil packs and ignition module, GM). A spark test might be helpful.
Looks like your basic 2-coil ignition system, with each coil firing 2 cylinders at the same time. When one of those cylinders is igniting the compressed fuel/air charge, the other cylinder receives a wasted spark on the exhaust stroke. Looks like cylinders 1 and 4 share one coil, while 2 and 3 share the other one.
Edit: Unless those are old photos and things have been cleaned since, I’d remove the coil pack and clean it up so it looks as close to showroom new as possible.
Of course, disable your ignition system by pulling the electrical connector at the coil or module before beginning this work. For extra safety, I pull the negative battery cable before working on some systems, especially ignition (lots of Amps, which can really hurt you). If your coils set on a module, I would give that a good cleaning (I used electrical contact cleaner). Don’t forget the undersides of the fastener heads too.
[quote=”jdphenix” post=141294]Correct. No dark residue around the tailpipe, or “blue smoke”, or anything that screams “hey dude you’re burning oil for fuel!” There’s a slight difference between the oil dipstick level between oil changes, but I never have had to add any oil between changes (checking weekly).
I did find this, which seems to be copypasta from Ford. The lowest reading being 25% within the highest reading is the spec. According to that, which would suggest that cylinder 3 is out of spec. Still it seems low across the board for what I’ve found on the interwebz otherwise. I’m seeing people report dry compression results on their Zetecs well above 150 psi.
No compressor unfortunately. I’m just a guy in an apartment parking lot. I’ll ask my buddies just to be sure but I don’t think I’ll be able to get access to one.[/quote]
That “Special Tool 303-F012” mentioned in your link is the leakdown tester that lar1969 was referring to. Compression on a normal, properly running, gasoline engine is 12-15 times the compression ratio (CR). The CR for your engine is 9.35 +/- 0.25. (9.35-0.25) * 12 = ~109, and (9.35+0.25) * 15 = 144. So, for the average daily driver that has been maintained appropriately, a reading between 109 and 144 with no more than a 10% difference would be considered “good” and above that would be “excellent” (the theoretical maximum compression is 20 x CR, or (9.35 + 0.25) * 20 = 192. The service limit is usually CR * 10, which would be ~94. Compression tests aren’t done just to find out the pressure, though. They are done to find consistency between the cylinders due to the fact that the rings should wear evenly across all cylinders, so a large deviation indicates a sealing fault. In a previous post you mentioned an acceptable deviation of 25%. (This is why the factory service manuals should always be consulted due to peculiarities of certain models. The rule of thumb sans manual is 10%.)However, your second compression test data puts you well into the “excellent” range, so I wouldn’t worry about an internal engine issue. The fact that the wet numbers are so close to the dry numbers indicates your rings are in very good shape.
A restriction in the catalytic converter can cause vibrations when the exhaust tone becomes resonant at a particular frequency. You can test this by removing the front O2 sensor and then see if the vibration changes.
The hydraulic mount was also mentioned. Its purpose is to dampen vibration from the engine. It is quite possible this mount has gone bad. DEA are good mounts, and RockAuto has the DEA hydraulic mount for <$40.
Got an update for you.
After a couple of days, the engine started to buck (misfire?, not sure what to call it) under load – specifically going uphill. I’m assuming this is due to the engine because it’s never done this before and I recently touched it. 🙂 No new CEL codes. I can also reproduce this issue 100% of the time if I do the stall speed test that’s outlined in the performance issues article. Looking at RPM data over time it’s a sudden drop of around 350 RPM over an average 250 milliseconds. It doesn’t seem to be restricted to a certain RPM range.
Anyhow, I’ll be going over my work – I’ll go ahead and clean up like you suggest while I’m in there.
I believe we are getting close to solving this issue.
When an engine bogs down under load, it usually indicates an ignition system issue.
Your cleaning and a visual inspection of the components should reveal anything out of the ordinary. Inspect the coil packs for cracks in the plastic casing, cracks or corrosion on any metal or contact points. Remember to disable the ignition system before beginning this work.A spark test would would confirm that your ignition system is producing adequate spark.
3:55m begins testing procedure
I did not suggest a voltage leakage test earlier in this thread because you had just replaced the wires, but if you have cracks in the plug wire insulation you could see electrical arcing on a humid day in a darkened garage and you would hear it as a snap or click, standing outside the car. You might also feel it as a hesitation while driving.
Thanks for keeping us posted on your progress.
The coil could bad also,using a pair of plug wire pliers remove one plug wire at a time being careful while it’s running.Should get a good spark doing this.If you see a weak spark,the coil is bad.Have someone to start and shut it off when you do this.The DIS is called a heart attack machine for this reason.
It sounds like you better go over your work if it has a misfire. Those engines are fairly tough but I didn’t like the look of the spark plug on the left in the pic. If the new ones are burned or melted you better find the cause. Possible vacuum leak. On a Focus all of the vacuum hoses are suspect especially the PCV system. They collapse and split. If the vibration at idle goes away with a jack under the engine the hydraulic mount is bad. I have replaced about 20 of them. Make sure you get one from Ford as the aftermarket ones are made in China and are junk.
No – thank YOU for walking me through a diagnosis to hunt this down. :woohoo: After doing all the things I discuss below there it is still acting up under load. One new thing I noticed is that it gets worse if the engine is warmed up. Going uphill cold it’s fine, warmed up it’s really struggling.
lar1969:
Spark test done. Scary as hell. Every wire scared me equally[s] – except cylinder #2. It sparks out of the wrong part of the plug. The others spark at the electrode end but cylinder 2’s plug sparks out of the porcelain (that’s what it is, right?) part. [/s] Nevermind – my fault. They all spark fine.When I cleaned up the coil pack there was this black gunky crap inside the part that you plug each spark plus wire into – it reminded me of grease, except stickier. Cleaned that out with a q-tip.
I’ll go ahead and do the voltage leak test tonight. It’s very humid here (Oklahoma) so that’ll be ideal. :cheer:
wafrederick:
Is there a way that I can measure good versus bad? I’m interested in testing this better – I did this and they all seem to be good.wysetech:
I planned on getting an OEM mount once I got this figured out. I just didn’t want to burn the cash to get one until I figure out if the car is worth it. I’ve heard plenty of bad things about anything else for that mount. I think the plugs were corroded because of a crack in a plug wire which I’ve since replaced. There’s been no more water getting in there since I did that.
Or rather, I decided to take the coil off. Here’s what I found.
Replaced, test drive, seems better. Still struggles uphill but not nearly as much as it was.
That’s a nice find. I have changed a few of them and I don’t recall ever seeing one fail there. They usually crack around where the wires go on. Again, nice work.
[quote=”wysetech” post=141900]That’s a nice find. I have changed a few of them and I don’t recall ever seeing one fail there. They usually crack around where the wires go on. Again, nice work.[/quote]
Wysetech, would that crack cause jd’s issue? I pictured, in my mind, a crack in the front plastic case or severe corrosion.
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