The Car Nobody Could Fix Pt1 

It's commonly known that the valve clearances on Honda V6 engines tighten up over time and cause issues. It's surprising that all the mechanics before you failed to check for this issue. Good job!

Nice case study! I believe these have no cam phasers and the valve timing is changed solely by engaging the 3rd rocker arm (VTEC) Surprised no one thought to adjust the valves which actually is a job that is "needed anyways" after a certain amount of miles.

Came for the artwork, stayed for the education! Love the thought process!

Very interesting! As a former air-cooled VW mechanic, I know valve adjustments are very important. And now to visit part 2.

Do a running compression check to see volumetric efficiency of the cylinders. You could also put a vacuum gauge on the engine and analyze the movement of the needle. You have the hood prop in the service position. There is another hole that would allow you to remove the fuse cover.

My truck had a high idle issue. I checked all my sensors. Found nothing. Replaced no parts. After 2 years it went away. My theory is it must have caught COVID since COVID mainly effects your respiratory system aka my truck was breathing hard, causing a fast idle

Running rich - that's at least some symptom to put your hands on. I have seen the opposite - running lean condition code and that was the MAP sensor, but the ECU didn't have a fault check for the MAP sensor. But driving the car revealed a situation similar to a lean carburetor. A nice idle is also a good start, it makes things a lot easier.

Extremely informative. Broke down loss of power whilst trying to accelerate - Garage diagnosed MAP problem. Pipe blocked with carbon including connection into manifold. This video so helpful. Going to take a look at readings using volt meter

My blood pressure went high when I heard how many parts those "mechanics" replaced on this engine. Even more so since it is a Honda. You do well, Matt. 👍🤗

Had same issue but with a pilot! Problem was clogged catalytic converter! Hello from California 👋

Manufacturers really need to get on board with in cylinder pressure transducer diagnostics. Give us specs for valve timing or just flat out give us known good waveforms. I mean we’ve been using pressure transducers for years so it’s about time they recognize it for the powerful tool it is.

This is an excellent video example of the failure of the whole electronic aspect of vehicle maintenance and complicated evolution. You have a vehicle with a years-long issue and yet there are no trouble codes. Has vehicle maintenance become easier? In a lot of cases there is reason for satisfaction but every so often you get this type of case. It should not be so.

You should do in-cylinder graphing of the compression. You can do running and cranking. You can measure valve timing in minutes. If you valve timing is off it the adjustment is off you can see it.

I think I would have started with a cam crank waveform and compared it with known good. Never know when you may have a bet off a tooth or two or have a sheared keyway, but in-cylinder pressure will tell you too if you have something opening at the wrong time. I made my own pressure transducer, and it has come in handy a few times.

I had a Honda CRV Come in with similar issues. Tuned out to be the Cat and REAR O2 sensor. Took a long time to figure out because in school I was taught the rear o2 is only for cat. monitoring........not the case anymore, it actively changed the fuel trim!!!!

Very intelligent way to troubleshoot and diagnose them A.K problems that 99% fail because they get overwhelmed and frustrated after they start with most commonly replaced part that is the part that resolved them symptoms . Reminds me of how I have seen my dad diagnose engines back in the. 60"s and I still use a basic vacuum gauge inmy diagnostic procedure that will help you know what the engine vacuum should be at certain given conditions and how the exhaust smells as a SWAG on the fuel ratio and just by watching the gauge and seeing the vacuum and ne needle fluctuations tells you what is happening with the engine and the component that causes the gauge to react like that while engine is running at the condition of your diagnostic procedure enjoy your videos and I am always learning when I see different ways people use to troubleshoot some things you don't use and sometimes you can see the difference ways that several people used and take all them and b are a better way that works for you

OneLeggedHondamechanic said, on a warm engine at temperature. the MAP voltage should be 0.85volts and that higher values can indicate tight Exhaust Valves.

Surging idle usually means it's not compensating for the lean/rich cycle the engine does to prolong the life of the catalytic convetor. Typically caused by a bad MAP sensor. Also explains the hestitation of the engine during accel, because that's what these Honda's predominantly use during WOT, as it goes into open loop. Not saying 100% this is the case, but it'd be what I'd look at first. But that'd just be me projecting, because I already regularly send my Acoord in for valve lash adjustment :D So it couldn't be that. And yeah, I had to really press my mechanic for the adjustment, because he didn't believe a modern car needed it xD

Everybody always skips the valve adjust. 210k service (timing belt, water pump, spark plugs AND valve adjust).The shop that replaced the timing belt was looking for easy money and didn't follow the recommended service interval properly. Surprised the HONDA dealer didn't look at the valve adjustment as a possible performance and drivability concern.

Hood is in the "service" position(opened a little more than just an oil change), if you move it to the other position(hood is closed a little more) you can open that fusebox easily/easier

Sounds like 'credit card engineering' by the various garages ! On Honda VVTi engines there may be a tiny mesh filter near the cylinder head which can become clogged and is a replaceable item..

10:00 Long Term fuel trims were absolutely stuck at - 8.6 and never made any adjustments at all.. So something is fishy there to me-- I've never seen them stay stuck and not fluctuate at least a little bit. ?? I'd definitely want to look at the 02 sensors with a scope and/ or a scan tool and see how they actually graph.. I wouldn't trust any of those parts just because they are new. Generic parts fail right out of the box all the time. Especially precision sensors like 02 and MAF sensors.

A pulse sensor ( like first look or Cody’s) in the exhaust will show the need for a valve adjustment especially on that engine. Brandon Steckler has a book and free uTube class that actually has a case study on that exact engine. Your pico pressure transducer will also work in the exhaust although I think it might be inverted

Mat, it is just a pleasure to watch your videos and learn from you. Thank you very much.🙏

Valve lash affect timing. Valve guides seals or with 200,000 miles valve guides. Does it burn oil gonna be stuck rings. Or is Walter Matthau said in the movies carbon on the valves affects the billing for the valves to close and could run rich. Let’s watch part two and see

A 4 CH Scope would be of great help here. And fuel gas angelize test. After hearing what all has been replaced and listing to the vehicle, I would have to narrow it down two things. Do we have stoki in the cylinder's? 14.7 to 1. Is there valve timing issues here. I'm thinking mechanical here.

With restrictions in fuel trims, that's an indication of lower combustible air volume, right? As to why the reduction in fuel?

Check exhaust back pressure at 2500 rpm. Oxygen sensor 1 bung is a good place to check the pressure. Bill G

I ran into the same problem .it ended up being a charge air temp sensor in the air filter box. Now to add a little more to this . The map sensor also can read air temp along with barometric pressure but the sensor I'm referring to is in the air box it's self .. I've seen problems with the plug and wires being broke from air filter being changed.. persons changing the filter sometime tend to be rough when trying to remove the filter.

Surprised dealer didn't suggest valve adjustments as that is something is missed lot until eventually usually will trigger random misfire or rich code. This very common on all v6 3.5 2003-2015

Nice study case sir. Many thanks to this channel as it helped me to pass (1st place) Motor vehicle electronics with a merit🤗. Am grateful for the free subscription as well🙏🙏

no doubt he is a master great case study definitely is going to be fix on part 2 can wait thanks master

Okay so I know this seems stupid but also take a look at the power steering pressure sensor and connector/wires. Issues here would cause drivability issues.

Timing chain may have been the original issue. Timing may be off now due to not relearning cam/crank correlation after replacement.

Hate to advise you it sounds like what my toy 4 runner did. Changed the exhaust system muffler not thec. Catilytic converter. Definitely didnt run as rich cut my emissions in half finally ran well the taken. It needed it anyway.lol

19:34 Low compression would cause the MAF to read less air suction which would cause the ecu to dump less fuel, less fuel would cause a lean condition. Think about it, you have say 4 cylinders, if all 4 were in good compression they would inhale say 400 cfm and the maf would relate that 400 cfm to the ecu and the ecu would release enough fuel for 400 cfm and it would run normal. If 1 cylinder was LOW on compression, it would not inhale 100 cfm, but maybe 50 or less. So instead of the motor inhaling 400 cfm which would be the normal, its only inhaling 325 or 350 cfm so the maf will tell the ecu that its breating 325 or 350 cfm and the ecu will release enough fuel to support 325 or 350 cfm which is NOT enough when its normally 400 cfm which will cause a LEAN condition .... now you got 4 pistons that are used to 400 cfm worth of fuel and now they are only getting 325 or 350 cfm worth of fuel ... less fuel = lean condition ...

OK. I am 7 minutes in the video and I am already asking myself if any one of those shops checked the valve clearances. The honda engines are well known for needing these adjusted atleast every 100k to ensure they are in spec.

You cant test the vtec while its idling because the system requires more oil pressure to be present than at just idle. The vehicle won't allow it or else you could cause damage to the motor when the vtec solenoid allows oil to run into the head and lock the rockers onto the high speed cam profile.

Very informative..the best teacher and diagnostician

The oil is it black does it indicate any metal in the oil pan. These things are known to have camshaft lob ware problems

Nice job. I also have a strange prob with a check engine light on a 2003 maxima with 58k miles which I'd like to find.

Just a data point. 2001 Jeep Grand Cherokee. Surging idle, but usually runs well. Look like the computer was seeing variable load (commanded ignition timing was all over the place. Finally, it stalled and I got the data from the computer. Seems the MAP sensor went from good vacuum to zero vacuum instantly. Turns out the MAP sensor itself was faulty - every now and then indexing to atmosphere. So... Look at the data streams. 12.9% load at idle? As for cam timing - yes compression test, but also vacuum. The scan tool said the absolute intake manifold was at 3.x psi and your barometer was at 11 (Are you in Colorado? - shouldn't it be more like 14....) so that is 8 psi vacuum (about 16 in Hg) That's a little on the light side for most passenger side cars. Hail Mary - put a smoke machine on it and look for a vacuum leak. The weird thing with computer control, just because it's not idling lean, doesn't mean its not a vacuum leak of sorts. The computer adjusts.... What would be really cool is to find another Honda, similar engine, and see where the sensors should be reading. As for your in cylinder pressure. That is a slippery slope. You can spend years on cam timing esp cam timing at idle. But if the exhaust valve timing is 250 degrees advertised, that means it has 70 degrees more than 1/2 turn. Split that and your looking at 35 degree advance. As for valve opening vs. air actually flowing. Most cam guys tell you NOT to look at advertised degrees - just because the valve is open .001 doesn't mean air is actually flowing... If you really want to see what is going on, they have laser drilled spark plugs that have piezio sensor directly in the combustion chamber.

What does the valves clearance looks like? Honda vehicle likes valves clearance to be on the max side, tight valves will cause fuel rich run rich condition

When you reved it the first time I heard knocking/tapping and was thinking valves and then you started mentioning them and did a compression test and I had to make this comment before you do anything on the valves or even see them

cool video, i enjoyed it for my lunch break. i'm excited for part II

Did you check the temperature it will run rich if it still cold. Then if it gets warm it will run lean.. Maybe you sgould chexk the temp and thermostat

Why didn't the main dealer check the service intervals? Tappet adjustment would have clearly been shown after reaching a certain millage,200,000 miles without adjusting tappets is crazy,A great diagnosis but when I work on my Pickup or one of my bikes I always carry out Maintainance according to service interval,

I've seen twisted cams and and a broken pen on the cam sprocket allowing the cam to shift ever so slightly causing a rich condition.

@9:22 That Firebird Symbol 💪💪

The parts changer voice always gets me, always!!! 😊

I have a 2010 I changed the engine immobilizer on a Toyota Camry 6cyl 3.5 and now it starts but it sounds like a vacuum leak

Only watched a few minutes in so far but with high miles Honda the valve clearance is always a suspect due to valve seat recession.

When I was at honda, "valve adjustment misfires" showed themselves when the engine was cold but went away when warm

Sir, you do mean that it's running LEAN because it has that minus character which means that it aint getting enough fuel, try adding fuel cleaner or change the air filter.

Not really familiar with that model but from all the symptoms you described the variable valve timing isn't working..

Would a fuse on a immobilizer system cause it to run like a vacuum leak?

Would a vacuum guage help you to pinpoint the issue?

Look at map voltage. Over 1 volt hot idle you need valve adjustment.

My dad had a 98 jeep grand cherokee laredo with the 5.9L V8 ... It cranked and ran for 5 seconds then shut off. It would crank and crank but no fire. Had no spark, replaced the coil, still no spark Replaced the crankshaft sensor and camshaft sensor, still no spark. Replaced the distributor, still nothing. The coil was not getting its signal. Replaced the ECU, fired over for 5 seconds and shut off again and would not fire over again but cranked and cranked. Got the ECU swapped again, fired over again and ran for 5 seconds then shut off again and would not fire over. Just crank crank crank. 3 mechanics could not find out why it would only run for 5 seconds ... We had to sell the car as is. The guy who purchased it ran into the same issue and could not figure it out, he junked the car.

I've seen late valve timing caused by a shear pin failure cause these symptoms.

I have a 2008 dodge caliber srt 4 that giving me code p0171 I have changed spark plugs ignition coils and oxygen sensor , and maf sensor and it still not running good do you think you can help me ???

What elevation are you at? That baro reading looked really low unless you’re at like 7000 feet or something. If you’re nowhere near that elevation might look into exhaust restriction especially if it’s down on power.

How to find rich or lean condition in petrol cars?? Thanks.

Just listening to idle definitely not cam lobe wear. Just by ear and years of working with Honda engines they tend to develop a very noticeable TICK with worn lobes

We bought a brand new bmw m1 convertible back in 2014 it had a similar fault to this out the dealers and I’ll give bmw there dew they tried and tried to fix it but in the end they actually took it back gave us another one because they couldn’t fix it either lol Interesting vid enjoyed it 👍

2000 c3500 iac keeps idle high during drive.. only comes down when car stops

The car nobody could fix finally fixed by somebody.

Did Some wiz-nat Mec-in-nic, change the first Timing Belt and get it timed Wrong, way back when? Wouldn't you Check Timing belt Marks First? Before tearing into Valve Adjustment?

having a oscilloscope is money well spent for diagnostics . a multi meter and clamp will get you into the rabbit hole and oscilloscope will get you out

Awesome!!! Cant wait to see part 3! i mean 2

at 15:15, it seems like you're mixing up VTEC/VCM with VVT. I'm not an expert, but my understanding is that even a VTEC system used for variable valve timing would not affect CMP signal, because it isn't phase shifting the cam, but instead affecting the rocker arms. However in this vehicle, IIUC, there isn't such a thing, but instead VTEC is only used for cylinder (de-)activation (VCM), and that seems to be what that test is for. VVT tests are probably hiding somewhere else.

Is it a press fit cam? I.e. are lobes press fit onto the shaft?

Same problems to my Nissan Murano...and change the alternator. Problem Solved.

Love valve adjustments!!

Time to check exhaust back pressure. ----2kpa, +6kpa, intake, exhaust respectivley.

would have been nice to see the pulse testing on the intake and exhaust

The problem is the manufacturer gave the Odyssey a reputation for not being a quality vehicle sadly enough , certain years are worse than other years

What's the MAF designed for a different size engine?

Hi Matt, great case study mate👌

I noticed that the air intake temp was 111 degrees and I don't see you sweeting.

Without watching yet - 3 culprits likely/possible - non OEM MAF.. non OEM Lambda sensor, V-tec not adjusted/starved for oil. With no lights lit - it's the Vtec more than likely. Maf/Lambda would probably light the light. That's after the boggo servicing/check exhaust etc etc is done. First up - go through the Vtec. Chances are it's not getting activated/enough oil/is out of sequence blah blah. Wouldn't even fire up the scanner for this one - poke the cams.

A couple of thoughts...the guy who replaced the purge valve was not wrong to go this direction (even though it didn't fix the car.) At this mileage, the purge valves on these can fail in a way where they will test good but be bad. They will fully open and fully close when they are supposed to but will be slow when the computer pulse width modulates it. I had one setting a fuel cap message (no DTC) on the gauge cluster that turned out to be a bad purge, even though it tested good. That threw me for quite a loop. That said, at 10 minutes into the video, my suspicion is it needs a valve adjustment. That is supposed to be done at 100K but nobody ever does it. Intake valves loosen up and exhaust valves tighten up. Mike Becker did a good video series on this. It takes a scope to prove it, though. Without that, there's enough evidence, and mileage, to justify a valve lash check. Edit: Well, a few more minutes in and I see you are already on to the valve adjustment theory. I agree. Also, the prop rod has two settings on the hood. In the position you have it the prop rod is in the way of the fuse box. In the lower position, it's not.

Did they use OEM parts or aftermarket junk?

Your moments of humility are a great balance for all your knowledge. Awesome video!

I'm thinking of a new business model. I'm going to start dumpster diving for parts....so many parts changers I could make a lot of money selling perfectly good parts that were thrown away.

Do you know that Honda use mechanical lifters

Is there some way to change the minimum "on time" for the fuel injectors? Maybe there is a firmware problem ? Did you check the fuel pressure?

Is it broken pin in cam?

Bad injectors?

No idea what may be going on But I feel like you are using a scientific way by using Cunningham's Law. 😂 Love your videos.

SUBSTANTIAL Schrodingers Box Thank you very much for sharing with us great tutorial God bless you and all your family around you Schrodingers Box From Nick Ayivor from London England UK 🇬🇧

when doing the running compression signal why not add another channel with ignition signal?

LOL, there are 2024 Hondas that still need valve adjustments as part of regular maintenance.

My 2006 Caravan had a bad TPS with no codes. Batty idle speed at times

YES HE'S BACK!!!!!!!!

Is it rich or is the ecm adding fuel there is a difference I've chased something similar before turned out to be an intake vacuum leak I would check that also.

when are you going to start doing live stream diagnostics?

I would datalog it and see if you are getting ignition advance when you are supposed to. My guess, a bad knock sensor mistakenly pulling timing causing it to run like dog poop. Also, I don't think that fault would trigger an engine code. Can you see ignition advance against rpm and engine load. If it was pulling timing as you rev up, it would also go rich, maybe? Het, also, when doing the compression test, make sure the throttle is WOT. Also, you can do a leak down test to tell you if the valve adjustment is so bad, that it is leaking pressure. Final random thought : Is the rubber on the harmonic dampener torn causing sensor signals to be retarded compared to what is actually happening? I would use a degree wheel and a screw in stop to confirm indicated is the same actual TDC.

(VTEC) solenoid has a oil screen in it that likes to get clogged.... WatchWesWork does a good video on this problem

Am I the only one thinking the MAF is not failed but is a tad off? Or was that already replaced with I'm sure an OEM unit.