2007 Acura TL-S with 150k miles. Automatic transmission and I’ve owned it since it had 30k miles. I’m having an issue where it stutters and hesitates around 1500-2000 rpm. Here’s the story of what happened. Short time ago I got misfire codes (P0300, P0301 though P0306) and tried to figure out which coil pack was giving me the problem. Tried to troubleshoot by taking off each coil pack one by one but nothing changed the way it ran. Had to go to work so I had no choice but to drive it. CEL blinked a couple times but it was drivable. Bought a scanner and saw that cylinder 1 had 100+ misfires and no other cylinder had any. Replaced the coil pack and spark plug. Stopped the misfires but then I got the P0420 code for the catalytic converter. I’m guessing I burnt it up when I drove it with the CEL flashing. Tested the second 02 sensor voltage with the scanner and it was bouncing everywhere. Replaced the converter and the code went away. O2 sensor now shows steady around .5v. Still had a hesitation so I replaced the pcv valve just because it was a cheap and easy attempt to fix. I don’t have any codes, nothing on the scanner to show me something is wrong and nothing to point me into the right position. I’m thinking it could possibly be the following but have no clue:

Coil packs and spark plugs
Third cat
O2 sensor (even though it tests ok)
Vacuum leak
Bent exhaust valve

Can’t be the transmission because it does it in park and while driving. I use 93 octane from the same station I’ve been using for years. Replaced the EGR valve 3 years ago. Without codes I’m kinda taking a shot in the dark.

 

Short term fuel trim is running at 10-25 depending on the RPM. Does not go down when I accelerate like a vacuum leak and it’s high on both cylinders. Bank 1 reads slightly lower. I’m guessing something is causing a lean condition so I’ll have to troubleshoot that.

 

Hopefully just an 02 sensor that needs replacing to clear the p0420 .



I know you replaced the EGR valve but pop it off again and make sure there isn't any carbon that's keeping it open/closed. I had an issue with a piece of carbon keeping the valve open and a pair of pliers later and I was good to go.

 

I’m not sure it’s the o2 sensor. Got a p0174 code after I reset the ECU.

after it ran a while, they went down.

I am almost thinking it has to be a vacuum leak.

 

 

https://www.google.com/search?rlz=1C...4dUDCAs&uact=5


see if these older threads help

 

oh man, seems like many people have had my same issue. Some say EGR, some say o2 sensors, and I also see it could be a intake manifold leak. Going to clean the EGR and smoke test for vacuum leaks. Hopefully one of those will point me in the right direction.

 

EGR valve looks good. Valve moves up and down, and it wasn’t as dirty as I thought it would be.

cant find any vacuum leaks. Tried spraying carb cleaner and tried a diy smoke machine test. Probably not the best method but was hoping I could see something.

Need to slap in the o2 sensor just to rule that out but it looks like I’m running out of the easy stuff to fix.

 

Could be a lazy o2 sensor. If/when you replace, make sure you use a non-Bosch ones.. Preferably OEM/Denso/NTK as previous people have posted really bad luck with Bosch and other aftermarket ones.

 

I did buy a denso. I’m hoping it’s the o2 sensor but I don’t have my hopes up.

 

Wasn’t the o2 sensor. Not sure what the next step is.

 

Could a valve adjustment fix my issues of running lean? It has 150k and never had one before. It’s really the only thing I haven’t ever done.

 

Did you end up doing the valve adjustment? Was it effective??
I'm having similar issues with my '08 TLS. Feels jerky in lower speeds. almost feels like it's not getting a throttle response when I'm slowly trying to accelerate and doesn't coast to stop signs and stop lights when I try to decel from my lower speed. It's also idles rough.
I know I'm going to be checking my throttle cable to make sure it doesn't have extra slack in it... I'm hoping that will help with the acceleration part of things.
​​​​​

 

^perhaps injectors are failing or clogged?

 

Could definitely be the reason...I'm gonna look up how to test them to make sure they're spraying properly. Thanks! 🤙

 

Have you looked at voltage outputs on your MAP sensor? Your problem sounds like one I had with a bad MAF sensor, but your TL only has MAP. I had no codes, but my MAF reading was haywire and caused lots of stalling and jerking.