I'm stumped (Honda Odyssey Idle Misfire)
I'm coming into this as a third party I'll be as complete with information as possible. Initial customer complaint was rough running one of my guys looked at it and recommended a #5 coil based upon output. We replaced the coil it ran brilliantly was test driven and returned to the customer a week or so later it came back running great but with a CEL misfires on the above cylinders. This is where I come into play taking over from the tech who worked on it before. Go through the basics unplugging coils doesn't clearly identify the problem cylinder.
Knowing common faults with these engines I begin by cleaning EGR passages and valve no improvement. (Gasket is not upside down)
Van is way overdo for a valve adjustment (200k owners are in love with it) adjust valves no improvement
Compression and cylinder leakage are normal
No intake leaks that we've identified.
Ran injectors on test bench and cleaned no change.
The thing that really has me puzzled here is raising the engine above idle instantly stops the misfire counts. At idle every few revolutions two counts occur back to back.
I hope the form of this post is acceptable I feel like there is something simple here I'm missing on this one and would like fresh eyes. If it's preferred I can post every test and their results in the order in which I performed them.
Thank you for your help.
Not sure which year software updates became possible on the Odyssey but I would recommend plugging in and seeing if there would be any software updates available for it, update it if something available then see if same symptoms still occur...
If you don't mind, I'd definitely be interested in seeing those tests.
I have encountered many Hondas that just had the valves adjusted. I frequently find that they are misadjusted and in fact, the cause of the rough idle/misfire, particularly at idle Can you tell us what fuel trims are at hot-idle/no-load, in park? Do you have access to a first look sensor?.
Maybe you could do a post or video on how to properly adjust valves on Hondas?
Bruce, that’s a great idea. I will do that next Tim I encounter one...THANKS!
The trick is to not use your feeler gauge and go by feel, you will know it is right when the engine is running by the sound ;-) A little play is better than a tight valve, it's only gonna get tighter!
I’ve often wondered how accurate feeler gauges are in terms of “feel” and when you consider high-mileage engines may have a recess worn into the valve tip. Have you ever tried using a dial indicator? Using a dial indicator would seemingly be the most accurate way (I haven’t tried it myself) but the most time consuming, except for having to go back in for Round 2 after goofing on Round 1. Are we
I haven't tried, but I imagine it would work well. I used to think using a dial indicator was a pain in the behind, until I got one of these: amazon.com/NOGA-Dial-Gage… You will never go back to any other dial indicator setup :-)
I use a dial indicator for most of the valve adjustments I do. Everyone thinks it should take more time to do them that way but I find it to be much faster and more accurate. I use a clamp mount base clamp it in place and go. I don't worry about zeroing the gauge, I just read it as I go, no worrying about which feeler gauge I'm using or if the amount of drag is correct or rechecking after
A misfire only at idle usually makes compression or fouled plugs pop into my head first. Was compression at all questionable or unequal? I believe mechanical time is easy to check on this? How did the plugs look? Is this a model with cylinder deactivation on the back bank? More information on what you've observed/ measured would be welcome.
How are the CKP, CMP signals? Is it possible that amplitude is too low at idle?
The one thing that sticks out to me is when you said it came back with a MIL for misfires but runs great points directly to a CASE relearn. Typical on some high-mileage GM V6 and V8 engine’s, as well as the HONDA 3.5L. I think the last HONDA I did required a 2-step procedure (first a clear, then the learn), but that was over a year ago, with many headache cars in between..
are codes set during engine fairly cold? ECT below 180F? Valves out of clearance is hard to diagnose without In Cylinder Pressure Transducer. In my experience, I’ve seen both + and - fuel trim, so fuel trim isn’t really going to be very helpful. i know the the valve adjustment was just done and made no improvement. would you mind redo it again but this time set your valves to the loose
I find it Much easier to spot with a FLS in the intake/cranking then to take the time to go in-cylinder. Nothing wrong with going in-cyl, just time consuming, relatively speaking
Brandon. Can you give more detail and share that method with us?
Guan, Id be happy to. First, be sure to research the specs as they vary from platform to platform. As others have stated,You then want to be sure the engine is cool to the touch, below 100deg F. Otherwise, when the engine cools, valve clearances will be loose and can lead to fuel trim issues. I place the engine at TDC-C#1 and give a good dose of WD-40 to the adjusters before running them up
Thanks for sharing Brandon!
I like my go/no-go stepped feeler gauges on these.
Bob, I had a 2008 Honda Accord 2.4L come in yesterday with multiple misfire codes. I've been servicing the vehicle for 385K miles. It ran fine at idle, but you could see the misfire counters increment upward continuously from startup. It only misfired when the PCM shut off an injector. Shorting the battery cable terminals together to "reset" the PCM had no effect. Resetting the adaptives with a
Danny, It's good to know that there is a crank sensor relearn on some Honda 2.4L too. One of my shop loaner cars is a 2006 Accord 2.4L w/ 240k miles. I'll remember that for sure. I don't even recall how I found that feature on the couple of 3.5L Odyssey's that I fixed. Sitting at idle with misfire counters going crazy while the engine ran perfectly smooth likely tripped my memory with the many
Being this is the "diagnostic network" My goal here is to help people figure out problems like this, without having to get their hands dirty. I would encourage you to put out of your mind any pattern failures, such as valve adjustment and let the scan data lead you to the problem. Things like vacuum leaks & EGR valves won't cause a misfire on this engine, unless the EGR valve is stuck open…
valve adjustment with engine stone cold in the morning it did happen to me ones I did the valve adjustments and I have misfire at idle , I was so confident I did it right but still rechecked, that particular cylinder was like 300 or 40 psi less than the others
What is the Map voltage at idle?
Honda’s are notorious for flagging the wrong cylinders. I’d like to see a cranking vacuum wave form. I’d also be curious what fuel trims are at idle vs what they are off idle.
As others have alluded to, there are better ways to approach diagnosing issues like this. Here is a waveform from a Honda I tightened a valve on. Check out videos on YouTube from some of the Diag.net members and search here for some good posts to learn the techniques that can prevent all the disassembly and guess work. Using a scope can make a technician more efficient and
Nice capture Matt. I don't know what is is about Honda, but you don't even have to "tighten" the valve lash closed to get a waveform like that.
Haha, yeah... my known goods are never very good looking on Honda. It is amazing how many of them need valve adjustments when you scope them. The reason I did this capture was to simulate one leaking with the other three valves adjusted well, since so many of them have variance.
I'm curious on it came back running great but with misfire counter, counting. Is the engine actually misfiring, or is the pcm counting a false misfire.
I'm Curious Of What Brand Spark Plug Is In The Vehicle.? Have Seen Bosch Platinum Spark Plugs Cause This Many Times