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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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Maybe it’s just the photo, but the plug on the left looks like it has a severely eroded center electrode, resulting in an excessive spark gap. This condition could likely result in a misfire, or prevent the plug from sparking at all, which could explain the rough running you’re experiencing. And the raw fuel being pumped out of the dead cylinder might be the cause of your cat issues.
I picked up a new set of Motorcraft plugs and wires and installed them. No change in the vibration but I earned some feel good points.
Here’s the well of that left-most plug,
They all look like that.
For the curious, this is the damage to the original wires that I suspect let water in,
The left-most plug belongs to this wire.
Have you checked this out?
http://www.ericthecarguy.com/faq/determining-the-causes-of-vehicle-vibrationsI know you said you did a visual inspection of the engine mounts but is it possible they are loose? You said they are intact but can you see any cracks in the rubber?
Seeing as you changed the plugs and wires and the vibration didn’t disappear, the condition warrants further investigation.
I would do a compression test next, both dry and wet. You have probably seen this but I thought I would include it any way.Hope this helps. Keep us informed of your progress. Thanks for using the ETCG forum.
P.S.- Its a good feeling to fix your own vehicles, isn’t it?Oh yeah. It’s great. As Eric said in a video (don’t remember which one), “make the machine your bitch”. 😉
The two rubber mounts are honestly fine. There’s no visible cracks in the rubber and they’re solid. There’s the hydraulic mount that I’m not sure exactly how to test. I found this test and the vibration nearly completely gone at idle when I jack up the engine. I obviously wouldn’t be able to tell going down the road until I replaced that mount. I’ll have to hold off on that one for a couple of weeks because Ford is really proud of their engine mounts and the aftermarket ones suck (any review I can find on them have them going out after months or weeks).
I’ll do a compression test tomorrow and see what I come up with. Thanks again 🙂
I was able to get a compression tester tonight. Warmed up the engine, ran the test, and here’s what I have for results. I made sure to have the throttle open during cranking.
Cyl Dry (psi) Wet (psi) Cyl 1 92 120 Cyl 2 113 121 Cyl 3 81 120 Cyl 4 93 120 I’m not nearly experienced enough to interpret the results here. I’m leaning toward run it until it dies one day, but some more eyes would be appreciated. From what I’ve been able to find I’d thought I’d expect to see something like burning oil, but I don’t lose any noticeable amount of oil (on the dipstick anyhow) between changes.
[quote=”jdphenix” post=141157]I was able to get a compression tester tonight. Warmed up the engine, ran the test, and here’s what I have for results. I made sure to have the throttle open during cranking.
Cyl Dry (psi) Wet (psi) Cyl 1 92 120 Cyl 2 113 121 Cyl 3 81 120 Cyl 4 93 120 I’m not nearly experienced enough to interpret the results here. I’m leaning toward run it until it dies one day, but some more eyes would be appreciated. From what I’ve been able to find I’d thought I’d expect to see something like burning oil, but I don’t lose any noticeable amount of oil (on the dipstick anyhow) between changes.[/quote]
You haven’t noticed an unusual dark (i.e. black) residue on the bumper around the tailpipe? It doesn’t consume a quart of oil between oil changes?
Those are pretty significant differences between wet and dry test compression tests. Were you able to dig up information regarding the Standard and Service Limit Specifications?
If you had access to an air compressor and a leak down gauge set, I’d suggest doing a Leak Down Test. You could always just modify your compression tester by removing the Schrader valve, hook your compression tester up to shop air and just run that through your cylinders, then listen for rushing air at the crankcase. You would want to confirm worn piston rings before condemning the engine…or as you have said, drive it till it dies.
PS-Nice work.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.
The age of the vehicle and (relatively) low mileage has me questioning a severely worn out engine, unless some previous owner really thrashed it on a daily basis and neglected regular oil changes. However, if your ring and bore condition really is as sloppy as the compression check suggests, you’d be seeing obvious signs of oil consumption and burning, and that doesn’t seem to be the case here.
Vibration issues aside for the moment, here’s a weird speculative scenario that might explain your low compression readings. Some manufacturers will produce head gaskets of different thicknesses for the same engine, sometimes depending on model year or engine application. I have no idea if alternate head gaskets are available for your engine, but if there are, then it’s possible that somebody has installed a wrong, thicker head gasket on this engine at some time in the past. It’s possible your cylinder bores and rings are perfectly fine, and the engine is just running with an artificially-low compression ratio.
If you want to investigate this scenario further, you’ll want to get in touch with a good dealership parts person and have them see if different head gaskets are available for this engine. Don’t limit your search to just the specific model and year of your car, but check several years and models.
Luckily I can answer that one for you with reasonable certainty. The car is a 3 owner car – myself, my father, and my grandmother. My grandmother kept great records and there was never a head gasket replaced in the first 80k miles. My father’s 6k or so miles is the one spot where I can vouch for records, but I can’t imagine 6k of no oil change would damage an otherwise healthy engine. What I don’t know is if there was a head gasket during that time – I doubt it though.
Would a block tester catch the “wrong head gasket” possibility? I’m also going to repeat the compression test with a different tester, just in-case that one was questionable.
Good info. Didn’t realize you had such detailed knowledge of the vehicle’s history. Safe to say you can scrap the head gasket scenario. It was an oddball shot in the dark anyway.
Doing another compression check with a different tester is a good idea, but if the test results are drastically different, which set of results do you believe? Then you’ll need to do another test with yet another tester to see if you can produce results that corroborate either of the first two tests.
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?
A block test wouldn’t hurt but wouldn’t there be other symptoms associated with a head gasket breach such as unexplained/unaccounted coolant loss, thick white smoke out the tail pipe even after warm-up, and/or power loss?
Has the vehicle overheated (which could cause gasket and/or head warpage)?Have you read this?
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
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