Actual vacuum leak or something else? P2279, mix too rich, and "misfires"
Yesterday, 05:23 PM
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2nd Gear
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Actual vacuum leak or something else? P2279, mix too rich, and "misfires"
Hi there! This is my first time posting, I've done a fair amount of basic repairs on the last few cars I've owned but I'd rate my skill level not far above "can only change oil with ease". I've owned my 2004 TL MT for about 3.5 years and I generally love it. This forum has been a great source of answers to questions I've had about this car, thank you very much to all you contributors! It has about 220k miles on it and for the last 6-9 months I've been experiencing intermittent stalling/idle drops to <500 rpm about 2-5 minutes after a cold start (car has been sitting for 8+ hours without being started/running) as well as occasional RPMs surging at idle after it's been running for a while. For at least the past several months it's been throwing the CEL codes listed below: P2279 intake air leak, P0172 & P0175 (mix too rich, both banks), and P0300 - P0306 (misfire on all cylinders as well as "random" cylinder). Shortly before this started, I replaced the APP sensor which fixed a problem where the car was in limp mode. I also had a local independent shop replace the rack & pinion, new serp belt, and do some suspension work which I assume isn't related to this problem, like rear sway bars and tie rod ends. Since this started happening, I've replaced the power steering pump and large air intake hose\ between the throttle body and air filter box (which did have a couple small splits in it), as well as replaced what I'd call the "intake manifold COVER gasket" and the two little manifold end gasket covers, replaced all spark plugs, gently tried to clean the throttle body, MAP sensor, PCV valve, and EGR valve port (but didn't thoroughly clean the entire EGR passage), and sprayed some top engine cleaner into the throttle body with the throttle partially open/engine running. Just yesterday I finally did a flush and fill on the dark brown PS fluid and replaced the PS fluid reservoir.
So, basically I'm trying to figure out if this is an "actual" vacuum leak somewhere or if it's something else causing these codes and symptoms. I assume the idle dropping just after a cold start, sometimes enough for it to die, as well as the surging at idle when warm (all intermittent, not all of the time) is caused by the computer trying to adjust the fuel/air mix to compensate for what it sees as reduced vacuum. My next plan is to take the TB off, try to clean it gently as best I can and replace its gasket. So some other possibilities which aren't too complex or expensive to replace would be to thoroughly clean the EGR port, replace PCV valve, replace MAP sensor. The more expensive options seem to be timing belt and checking/adjusting valve clearance which I don't think I'm comfortable enough to do myself but I just passed maintenance B4 so those should probably be done soon anyways. I have looked around for any obviously worn/cracked/loose vacuum hoses but nothing sticks out. What do you folks think, is there anything cheap/easy to replace or clean which I've overlooked or sticks out to you as a common issue with these cars or that you've experienced? Could it maybe be a fuel issue like a failing fuel pump or filter?
Car Scanner ELM OBD2
Version: 1.110.0/401100/GP
DTC report
Connection profile: Acura Honda/Acura HybridsDate: 8/27/2024 4:18:55 PM
============================
OBD-IIOBD-II
DTCs: 10
----------------------------
P2279 [0x2279]
Intake air leak
Intake Air System Leak
Status: Confirmed
----------------------------
P0172 [0x0172]
System too rich, bank 1
Fuel System Too Rich
Status: Confirmed
----------------------------
P0175 [0x0175]
System too rich, bank 2
Front Bank (Bank 2) Fuel System Too Rich
Status: Confirmed
----------------------------
P0301 [0x0301]
Cylinder 1 - misfire detected
No. 1 Cylinder Misfire
Status: Confirmed
----------------------------
P0302 [0x0302]
Cylinder 2 - misfire detected
No. 2 Cylinder Misfire
Status: Confirmed
----------------------------
P0303 [0x0303]
Cylinder 3 - misfire detected
No. 3 Cylinder Misfire
Status: Confirmed
----------------------------
P0304 [0x0304]
Cylinder 4 - misfire detected
No. 4 Cylinder Misfire
Status: Confirmed
----------------------------
P0305 [0x0305]
Cylinder 5 - misfire detected
No. 5 Cylinder Misfire
Status: Confirmed
----------------------------
P0306 [0x0306]
Cylinder 6 - misfire detected
No. 6 Cylinder Misfire
Status: Confirmed
----------------------------
P0300 [0x0300]
Random/multiple cylinder(s) - misfire detected
Random Misfire
Status: Confirmed
So, basically I'm trying to figure out if this is an "actual" vacuum leak somewhere or if it's something else causing these codes and symptoms. I assume the idle dropping just after a cold start, sometimes enough for it to die, as well as the surging at idle when warm (all intermittent, not all of the time) is caused by the computer trying to adjust the fuel/air mix to compensate for what it sees as reduced vacuum. My next plan is to take the TB off, try to clean it gently as best I can and replace its gasket. So some other possibilities which aren't too complex or expensive to replace would be to thoroughly clean the EGR port, replace PCV valve, replace MAP sensor. The more expensive options seem to be timing belt and checking/adjusting valve clearance which I don't think I'm comfortable enough to do myself but I just passed maintenance B4 so those should probably be done soon anyways. I have looked around for any obviously worn/cracked/loose vacuum hoses but nothing sticks out. What do you folks think, is there anything cheap/easy to replace or clean which I've overlooked or sticks out to you as a common issue with these cars or that you've experienced? Could it maybe be a fuel issue like a failing fuel pump or filter?
Car Scanner ELM OBD2
Version: 1.110.0/401100/GP
DTC report
Connection profile: Acura Honda/Acura HybridsDate: 8/27/2024 4:18:55 PM
============================
OBD-IIOBD-II
DTCs: 10
----------------------------
P2279 [0x2279]
Intake air leak
Intake Air System Leak
Status: Confirmed
----------------------------
P0172 [0x0172]
System too rich, bank 1
Fuel System Too Rich
Status: Confirmed
----------------------------
P0175 [0x0175]
System too rich, bank 2
Front Bank (Bank 2) Fuel System Too Rich
Status: Confirmed
----------------------------
P0301 [0x0301]
Cylinder 1 - misfire detected
No. 1 Cylinder Misfire
Status: Confirmed
----------------------------
P0302 [0x0302]
Cylinder 2 - misfire detected
No. 2 Cylinder Misfire
Status: Confirmed
----------------------------
P0303 [0x0303]
Cylinder 3 - misfire detected
No. 3 Cylinder Misfire
Status: Confirmed
----------------------------
P0304 [0x0304]
Cylinder 4 - misfire detected
No. 4 Cylinder Misfire
Status: Confirmed
----------------------------
P0305 [0x0305]
Cylinder 5 - misfire detected
No. 5 Cylinder Misfire
Status: Confirmed
----------------------------
P0306 [0x0306]
Cylinder 6 - misfire detected
No. 6 Cylinder Misfire
Status: Confirmed
----------------------------
P0300 [0x0300]
Random/multiple cylinder(s) - misfire detected
Random Misfire
Status: Confirmed
Yesterday, 07:17 PM
#2
Suzuka Master
iTrader: (1)
Can you specifically point out which of the below you replaced?
Intake Manifold - 2004 Acura TL 4 Door SPORT KA 6MT (acurapartswarehouse.com)
For the intermittent stalling/idle drops / occasional RPMs surging at idle:
When you cleaned the DBW throttle body, did you manually move the butterfly valve with the key off during the cleaning process?
Yesterday, 09:46 PM
#3
2nd Gear
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The gaskets i replaced look like #s 6 & 7 in that pic.
And yeah i think i did manually move the butterfly valve on the TB while the key was out but it seemed to return to its normal closed position as soon as i let go of it. However, as I recall this was after the stalling and surging started so I assume that alone didn't cause the problem. And since touching the butterfly valve, I did the "idle relearn" process, both the key off/accelerator down method and the "open throttle part way with engine running after battery disconnect" method so I assumed any potential damage to the butterfly valve calibration would have been fixed. Unless they're so sensitive that something else needs to be done to get it back to normal? I've done a lot of regular driving since then and disconnected the battery several times so I figured the computer should be as re-calibrated as it possibly could be.
And yeah i think i did manually move the butterfly valve on the TB while the key was out but it seemed to return to its normal closed position as soon as i let go of it. However, as I recall this was after the stalling and surging started so I assume that alone didn't cause the problem. And since touching the butterfly valve, I did the "idle relearn" process, both the key off/accelerator down method and the "open throttle part way with engine running after battery disconnect" method so I assumed any potential damage to the butterfly valve calibration would have been fixed. Unless they're so sensitive that something else needs to be done to get it back to normal? I've done a lot of regular driving since then and disconnected the battery several times so I figured the computer should be as re-calibrated as it possibly could be.
Yesterday, 10:03 PM
#4
Suzuka Master
iTrader: (1)
The gaskets i replaced look like #s 6 & 7 in that pic.
And yeah i think i did manually move the butterfly valve on the TB while the key was out but it seemed to return to its normal closed position as soon as i let go of it. However, as I recall this was after the stalling and surging started so I assume that alone didn't cause the problem. And since touching the butterfly valve, I did the "idle relearn" process, both the key off/accelerator down method and the "open throttle part way with engine running after battery disconnect" method so I assumed any potential damage to the butterfly valve calibration would have been fixed. Unless they're so sensitive that something else needs to be done to get it back to normal? I've done a lot of regular driving since then and disconnected the battery several times so I figured the computer should be as re-calibrated as it possibly could be.
And yeah i think i did manually move the butterfly valve on the TB while the key was out but it seemed to return to its normal closed position as soon as i let go of it. However, as I recall this was after the stalling and surging started so I assume that alone didn't cause the problem. And since touching the butterfly valve, I did the "idle relearn" process, both the key off/accelerator down method and the "open throttle part way with engine running after battery disconnect" method so I assumed any potential damage to the butterfly valve calibration would have been fixed. Unless they're so sensitive that something else needs to be done to get it back to normal? I've done a lot of regular driving since then and disconnected the battery several times so I figured the computer should be as re-calibrated as it possibly could be.
Open manifold to clean buildup? - AcuraZine - Acura Enthusiast Community
DBW TB's are 'sensitive' and the 'Throttle Position Learning Check' may be needed to remedy your intermittent stalling/idle drops / occasional RPMs surging at idle issue?
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