My 2009 TL is getting check engine codes for misfire on multiple cylinders, check emissions message and the VSA light comes on after driving for a bit. The VSA light turns off after shutting the car off but will come back on after driving it again. My mechanic, while not having experience with Acura's, has worked on plenty of Honda's. Plugs were done about a year ago when the TB/WP was done. He just did a valve adjustment and was confident that was the cause, said they were out of spec but he'd seen much worse. Engine was quiet before and this didn't make any difference.

Appears I may have stumped him, any thoughts on what this could be?

 

Update from my mechanic:

Compression is good
Did a leak down test, all good
EGR is good
Plugs and coils are fine
O2 sensors are fine, AFR is good
accelerator pedal senor and throttle body sensor are fine
He's checked a bunch of others stuff and he is currently stumped. He has about 12 hours of diagnostic time in it so far, only charging me for 2 hours. He is taking this a challenge and wants to keep digging. I don't need the car back anytime soon so I said go ahead.

I'll update when I know more

 

Please keep us updated. I also have a 2009 but mine runs perfect. Never know when this problem might creep up.

 

Which cylinders misfires?

 

tell him to put a scope on the alternator directly (not the battery) and see if the voltage regulator is working properly. Voltage spikes freak the ECU out and cause random lights. My 07 MDX did the same thing recently. New alternator, Positive and neg battery cable and good to go!

 

You must had charging error.

 

looks like 2 & 6

 

What was compression reading, and do have a picture of spark plugs?
How much oil you are burning?
Is there less misfires when the engine reaches full operating temperature?
Was there any injector "cleaning" procedure completed by your mechanic?

 

I don't know what the exact compression numbers were other than they were good
plugs have about 20K miles on them
I don't burn a drop of oil between changes
engine temp doesn't affect the misfire/surging which is only noticeable at lower RPM, I noticed it initially when I had the cruise control set at ~45mph. Much less noticeable 70+mph.
he checked the injectors, he said they are pulsing fine

 

Are you experiencing hard engine starts?
Do you lose any antifreeze?
Do you have picture of a combustion chamber?
How many approximately misfires per 255 cycle per each cylinder?
Was there some kind event that you could recall, which could caused misfires to happened?

 

Starts exactly as it always had, which is to say easily
Not losing any antifreeze
no pictures of the combustion chamber
no event that I can recall other than "did you feel that?" which after a week or so that led to the the codes
again, if you're doing 70+ plus mph you'd never know there was an issue. It's more RPM related than speed, I can go 45 but be in 3rd gear and not get any "surging"

He's convinced its electrical. Like I said, I don't need the car so if it takes him a month to figure it out, that's fine. He really wants to get to the bottom of this.

 

Did he check for visible spark just to make sure its not skiping ignition. Also would be nice to know how often misfire happens per 255 cycle.

 

I don't know how he confirmed spark, I'll ask him about the /cycle misfires

thanks

 

After thoroughly stumping my independent mechanic, ended up going to the local Honda dealer who said they have a good Acura guy. They find the valves are out of adjustment even after my guy had just down them. Whatever, just do it and I'll fight this out with him later. They do the valves and no change, still the same misfire. They say I need 2 injectors but recommend I change all 6 for only $750. Said I'm good, I'll pick it up. Talk with my guy and he said they moved the 2 from the missing firing cylinder to another location and the misfire stayed in the same place and didn't follow the injector and doesn't believe that's the issue. I e-mailed the service guy at Honda about this and haven't heard back.

to be continued...............

 

My bet is on bad coils!

 

My guy replaced all 6 with new ones, still had the same misfires. put the originals ones back in and returned the new ones

 

you never answered to some of my questions. Did they actually confirmed is there a spark? And if there is, is it skipping?

 

I am going to assume so based on what tests he did and my conversations with him. I'll see if I can get confirmation

 

I'm wondering if the catalyst has failed (common on rear bank of J37 engines) and is causing misfires... Also be sure to check the wiring as a loose wire to the connector will cause all these issues.

 

His misfires on two different banks. It is not cat

 

I had the same problem was the number 5 n 6 coil took it to Acura these mechanics where I am ass so I just go the dealer now charger like 5 suin to change em plus labor included

 

Also check the fcan ,the lights are on mine now the same but it’s giving me a fcan error now .at first was the coils but I think I just gotta drive it for a bit until it clears .

 

Well, after many months and 3 mechanics, the problem has been solved. Despite the fact that they were replaced about 20K ago when the TB/WP was done, I had 2 bad spark plugs. There were small cracks in the porcelain, I'm not sure I would have even noticed them.