I have a 2010 Honda Pilot 180k miles AWD. I but this with 150k miles on it.
Last year check engine light on had my mechanic check told me it was the a bad cat had them change it not oem but new. During next 12 month engine light would come one a day or so then go off randomly Codes were for o2 sensor and something about low efficiency I dont have exact code numbers.
Last month engine light started the car wold not accelerate and started bucking. Towed it to Honda dealer. They said it was misfires in 3-4-6 cylinders. and cause was Air intake hose had tears. They replace it.
A week of driving later same thing engine light on car bucking but made it to work. O lunch that same day started up it acted fine took it back to Honda dealer. Its been there for 3 weeks.
Honda says misfire codes in 3-4-5 cylinders they say they have pinpointed it through their checks and misfire only happens when driving 45-50mph on light acceleration. They giving data from car to Honda hotline for fixes this is time consuming because it take 2 days for Honda to respond to them and 2 days to order a part for for the fix suggested bu Honda.
What they have done is in their order:
swapped coils around -- same misfire
swapped plugs around -- same misfire
swapped injectors around -- same misfire
cleaned EGR ports under manifold cover same misire
checked EGR valve says its working fine
checked PCV valve says its working fine
Changed fuel cross over tube -- same misfire
New plugs same -- misfire
pulled O2 sensor scoped the Cat says its looks clean (this is the new one that was just replaced last year)
So now they want to replace o2 sensor on that cat the downstream one. Also giving me the once over because the cat is not a Honda OE cat.
FYI no I never had a VCM tuner or VCM Disabler on this pilot. Want one but all back ordered.
At as loss of what now. They have me $900 in hole now.
Another update.......What 1 month and over $1000 got me. A big fat nothing and $1000 bill.
After bringing my vehicle in for service and and them changing multiple items on car to fix an misfire. Move plugs then changed them, moving injectors, change O2 the down sensor between radiator and engine, claimed they cleaned EGR ports, and changed the fuel crossover tube. none of this fixed problem.
Days waiting for parts they never had in stock so they can change something.
Days waiting for Honda help line to call them back cause they couldn't figure it out themselfs.
Not truly listening to me as to what I though the problem was.
I ended up paying for the little of nothing work they did do and took my care elsewhere. Still having the same problem.
Solution took it to new mechanic problem solved so far. What they did was change the PVC valve and the EGR valve and cleaned EGR ports. They also said my upper plenum was warped so they machined it .005 to correct then changed intake manifold gasket. So far so good had the car back no issues yet.
Yes I did suggest to the Honda dealer to change the EGR valve and the PVC valve. They ignored that. I bought both parts online and was going to do it myself had them in car when I took to new mechanic he put them both on for 30 min labor only charge. The following pictures show what the mechanic I took pilot too took out that the Honda dealer ignored. Except the spark plugs.
https://www.piloteers.org/attachments/img_20220429_170819-jpg.159244 /" alt="" data-src="/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/ https://www.piloteers.org/attachments/img_20220429_170819-jpg.159244 /" data-zoom-target="1" data-url="" /> https://www.piloteers.org/attachments/img_20220429_170850-jpg.159245 /" alt="" data-src="/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/ https://www.piloteers.org/attachments/img_20220429_170850-jpg.159245 /" data-zoom-target="1" data-url="" /> https://www.piloteers.org/attachments/img_20220429_171035-jpg.159246 /" alt="" data-src="/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/ https://www.piloteers.org/attachments/img_20220429_171035-jpg.159246 /" data-zoom-target="1" data-url="" />Thanks for the update, and glad the new mechanic was able to work with you to resolve the issue.
Wouldn't I have an oil leak if the valve gasket was blown or leaking.
Engine is dry as a bone. Is that what the compression test finds out?
No. A cylinder compression test measures how much pressure the cylinders can hold.
A tight seal is required for proper engine operation.
https://www.motortrend.com/how-to/engine-diagnosis-leakdown-compression-test/
Do compression test on those cylinder that have misfire.
Wouldn't I have an oil leak if the valve gasket was blown or leaking. Engine is dry as a bone. Is that what the compression test finds out?
Not necessarily. If the piston rings are worn, your car burns oil without external leak. The test is to find out the condition of the piston rings.
What about valve adjustment? Hondas are known to throw misfire codes when valves need to be adjusted. Exhaust valves tend to be the culprit, there always too tight and out of specs.
Find a good independent mechanic with absolutely no connection to the mindless wrench benders at the Honda dealer.
easier sad than dont here where I live
update
O2 sensor replaced same misfire.
he also gave me my old plugs and they do not look bad at all and not oil soaked either normal carbon just at tip. Not white ash either.
And in my original post I incorrectly said which cylinders were misfiring. The ones that misfire are 4-5-6 and only them when the car gets to 40mph.
I asked Honda tech to do a compression test he stated he didn't think that was problem and was not recommended by Honda helpline.
I also asked about valve adjustments he said I next scheduled adjustment wasn't due till 210k he stated valve adjustment right at 105k and timing belt. tried to explain to him I dont know when first was done or if done at all. I bought car with 150k miles.
This Honda dealer in town had no experience techs they were all just wrench turners and had to be told by Honda hotline what to do.
I'm going to go pick the car up anyway and see about a valve adjustment. Find someone that can do a valve adjustment see how much that will cost.
Update 2 so i picked the car up from dealer. The adviser there still a random misfire and adviser had no clue as to the real reason for it. He claims its the non OE cat. He claims if misfire was cause by the need of valve adjustment the misfire would not randomly happen it would misfire from start up till you turn it off. He also says if it was because or lack of compression it misfire all the time. Dealer game me quote for valve adjustment at $610.
On service ticket its written that misfire only happens at 45-50 mph on light acceleration.he say the readouts he gets show the car will not go into VCM mode and car is running 6 cylinders all the time.
So on way home no issues never got above 40 mph and no service anything lights on the dash. The ECO light came on after 3 miles off and on with all the stops I have to make in town nothing before that though.
I called the mechanic that put the Cat on he claims cat wont cause misfires randomly if the cat was bad it would misfire all the time.
Oh and i called multiple repair shops in town only 2 would risk doing an adjustment both are nationally know dragsters. 6 others would not risk it or not experienced enough to do them.
That is just unbelievable. How sad.