fleabag

No **** they don't align nicely. A thousandth of an inch is certainly less precise than listing the fraction of a millimeter as a millimeter is much smaller than an inch.

bulwnkl

The units used has nothing to do with the level of precision. One can specify 1, 2, 3, or however many significant figures one chooses in either unit. If Honda chose to be inaccurate with one of their listed units, that's a different matter.

de63

Help me understand something, here...
1) these clues you list, are they for a properly-operating system, or the indicator of trouble with valve clearance?...and...
2) when you say " <-12% LTFT ", do you mean -13% on down, or -11% on up (to 0)?
3) Are these readings taken at idle or in motion?

I had the reader on this morning during a drive, and was monitoring these stats but realized shortly after starting that I needed these reference points clarified before I could understand better what I was seeing.

fleabag

A long term fuel trim of -12% means it's PULLING fuel which is an abnormal condition. +/- 5% Long term fuel trim is normal.

de63

aaahhhh. Much more sense. Thank you.
No one has ever really explained that to me, honestly. I came by the reader in a circuitous fashion, so I've been using it to diagnose codes more than deeper diagnostics.

Now to figure out how to get the LTFT numbers back in line... I recall them being kinda 'all over the place'.

de63

Okay, so... just got back from a trip to the grocery and a couple of other stops. Had the reader on, and here's what I saw:

I idled in the driveway for a couple of minutes, after first starting. B1 LT and ST both sat at -13.2% for the whole time.
After starting to drive, Bank 2 behaved pretty normally, very rarely getting to anything lower than -5.
Bank 1, on the other hand, was weird. STFT stayed within normal for a reasonable portion of the trip, but dipped below -5 more often than B2. LTFT parked itself at -13.2%. And I mean, it did not budge.
I got one instance of 301 during the trip.


On one particular hill/rise, I gunned it just to see what would happen; B1 STFT, and B2 STFT/LTFT both hung out around 0, acted pretty normal... B1 LTFT stayed rock-steady at -13.2%.

Thoughts?

de63

Okay...no one seems to be interested, but I'll keep trying...

Last night, did an approximately 60-mile round trip, to DIA and back. Had a reader on the whole time, and both ST and LT numbers were perfectly normal. You'd think the car never had an issue to begin with.

fleabag

those Long Term Fuel trims are per that RPM and I think load condition. I.e. So if you're idling the vehicle, the Long term fuel trims should be different than when you're cruising on the freeway. This is important as conditions are different at idle than when you're cruising and also when you're accelerating. If the LTFT is -13 when idling, you could have a valve lash issue, a weak/corroded electrical grounds which are affecting how the car is operating, or leaky fuel injectors. Do the cheapest stuff first which is clean up all your electrical grounds in your engine bay and do a valve lash adjustment. If both are done properly and you don't have weak ignition, you're not burning significant amounts of oil, or some other very odd situation, then you've got leaky/bad injectors.

If you had a LTFT of +13 (adding fuel) @ idle, there would be a whole host of more things that can cause that issue than a LTFT of -13.

piloteerfrommn

This thread is right on about valve adjustments. I had the following data with a P0175 recurring issue on a 2006 Pilot EX 4WD.

Freeze frame information:
------------------
Fuel Status = 0 byte
Engine Load = 32.157 %
Engine Coolant Temperature = 95 °C
Fuel Trim Bank 1 Short Term = -8.594 %
Fuel Trim Bank 1 Long Term = -7.812 %
Fuel Trim Bank 2 Short Term = -15.625 %
Fuel Trim Bank 2 Long Term = -16.406 %
Intake Manifold Pressure = 4.641 psi
Engine RPM = 733 rpm
Speed (OBD) = 0 km/h
Timing Advance = 9.5 °
Intake Air Temperature = 33 °C
Throttle Position(Manifold) = 16.078 %
Relative Throttle Position = 5.882 %
End of report.

I replaced the EGR and did the valve adjustment. Every exhaust valve was too tight, and every single intake valve was loose. After adjustment, which HondaEnjineer said was for advanced mechanics (he is correct), the LTFTs are 0 for bank 1 and -1.6 for bank 2. And the engine runs waaay smoother. Get the valve clearance checks done. Whether you do it yourself, or have a shop do it, get it done if you have high negative LTFTs. It was needed on my 06 Pilot, big time. I made it to about 140K miles before it was an issue that kicked a code. Now I'll just monitor my LTFTs for trends and perform the adjustment if they get way out of tolerance.

UtahJohn

This thread is one of the best that I've been able to find on the Internet about this problem. Thank you to all the posters!




Here's what I probably need some help with. I have a 2005 Honda Pilot (~122,000 miles). I am getting the P0172 and P0175 codes. When idling, especially once it's warmed up a little, the engine makes this awful metallic sound that I think sounds a lot like a diesel engine. If anyone wants to hear, I've uploaded a video to YouTube ( ) that is probably too long, but I wanted to show a lot of different situations with it so people who aren't test driving it with me can get a better idea.
Anyway, my best guess is that I need to do the valve adjustment. That's where things get complicated. I have read another post or two telling people that if you've never done a valve adjustment before, the Pilot's engine is not the place to start. Unfortunately, I live in Bosnia & Herzegovina, where Honda is a rare thing, let alone the Pilot, which is not on the European market. Likely, I will have to find an independent mechanic or a dealer for another automaker or I can try to do it myself (the Haynes manual and I have made it through some other things on this car and on a Subaru we used to own). If I need to replace gaskets, etc., which I understand that I will, I will need to supply that regardless of who does the work. So, what parts should I be prepared with before tackling the job or asking someone else to do it? (All suggestions are welcome, such as changing the spark plugs while I'm at it, which is one thing I'm thinking about, etc.)
Thanks in advance!

Mark Petereit

I don't want to scare you too much, just want you to be aware. I brought my 2009 Honda Pilot in to diagnose what sounded like a ticking lifter to me. They found that one of my cam lobes was completely sheared off!

The way your Pilot sounds starting up, it definitely sounds like you have some type of valve condition, either a sheared lobe like I had or something more simple like a stuck-open valve. In either case, unless you're a VERY skilled mechanic, it's probably not something I'd try to tackle myself.

piloteerfrommn

UtahJohn: That idle sound like pretty terrible knocking. Couple of questions. Has the timing belt and tensioner ever been changed? Do you have the snapshot data from the code reader as to what the actual fuel trims actually are when the fault gets recorded? The data should still be there unless you erased the codes. Something is messed up and like stated it might be a camshaft or it could be a timing belt issue. Regardless, you're going to have to get into that motor and diagnose things visually. Timing belt is a pretty in-depth job, and so is the valve cover removal but regardless something is way wrong with all that knocking.

UtahJohn

I just wanted to reply to this thread because I ended up having a lot of work done on the Pilot after taking it to a mechanic (when you live in Europe and have an American- and Asian-market car, this is problematic). It has taken a few return trips, and I am quiet familiar with some of the CEL codes that I wasn't before. A couple people also looked at the video that I had posted, and had helpful comments. The base problem was that the engine was running way to hot (coolant had leaked out). There were problems that were byproducts of that. Nine months later, I think we're good as far as the engine parts are concerned. (I would have to go and look at my notes in the car to have the full list of what we've replaced. I will do it later today just so the curious can see what was up.)
So, here's the list (that is still probably missing some things, but I went back and looked at my RockAuto and Amazon orders (they're lifesavers if one is not in the U.S.)):
- drive belt and tensioner
- all exhaust and intake valves
- engine timing belt and components
- all engine gaskets
- engine knock sensor
- front and rear catalytic converters and the four oxygen sensors that accompany them
- oil and filter change
- air filter change
- spark plugs
- ignition coils
- fuel pump (not really related (at least, not that I know of), but went out about the same time, so got to have that replaced, too)

speedlever

I'm curious what caused the coolant to leak out? And am also surprised you didn't warp/crack a head.

Odyssey08-A6eng

I just finished my shade tree, in the yard outdoors, valve adjustment on my 08' Odyssey. That's the 3.5 liter A6 engine. It was the first valve adjustment for it. The mileage is almost 200K. There were no glaring symptoms of needing it. The idle was just noticeably, not as smooth as it used to be. Only one or two exhaust valves were just right, and didn't need adjusting. About four of the exhaust were tight beyond specs., as tight as 0.009. All of the intake valves were quite loose, beyond specs. I wished that I had feeler gauges with the angle at the end inch, or so. I tried bending a straight one into a bend. But that's impossible to do without snapping the hardened metal. So I just had to take extra time to flatten the metal gauge in the tight space, to minimize the bowing, and feel the tolerance right.
The idle is super smooth now. I also hope for improved mileage. The seals that are pressed into the valve cover that seal around metal tubes for the coil packs weren't leaking but had lost most of their resilience, and needed changing. -Hope this info helps.

speedlever

That's pretty much what I would expect to find.. tight exhaust valves and loose intake valves. All which make me wonder at Honda's admonition to only check the valves if they are "noisy".

Correct me if I'm wrong, but I think tight valves are pretty silent, right? But loose valves can be noisy. However, it's my opinion that more engine damage can occur with too tight valves rather than too loose valves. Agree?