NTXChris
Well-Known Member
- Joined
- Dec 28, 2020
- Threads
- 3
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- Location
- North Texas
- First Name
- Chris
- Vehicle(s)
- 2019 PP1 GT
- Thread starter
- #1
I could use a little help from the forum. I have a 2019 GT/6 speed with roughly 112,000 miles . Only engine mods are a K&N CAI (63-2605, no tune required) and X-pipe. The intake has been on the car for about 5 years and the filter is cleaned regularly.
In the past couple of weeks, I've been getting the following DTCs: P0171 and P0174 (system too lean bank 1 and 2), usually occurring together. Other times I'll get P0420 or P0430 (catalyst below efficiency bank 1 and 2), but never at the same time. I'll clear the codes and be ok for a day or two before they come back, so before the readiness cycle completes. The car starts and runs fine both cold and hot and Idles around 640 RPM indicated on the dash. Occasionally the idle will dip when the fans come on (becaue Texas. AC is on 24/7) and other times throttle response can be a little sluggish off idle when I acclerate from a stop. This leads me to believe I have a vacuum leak somewhere, I just want to do a sanity check before I go down the wrong rabbit hole.
I've sprayed brake cleaner at all fittings between the MAF and throttle body, MAF included, while the car is running. Doing that has no effect on the idle speed, telling me that there probably isn't a vacuum leak between the MAF and throttle body. I plan to pull the engine cover this weekend and spray brake cleaner around the intake manifold fittings and fuel injectors and also test the EVAP purge valve (no EVAP related codes, though) for vacuum on the tank-side fitting.
I've logged PIDs looking at both short and long term fuel trims for both banks, MAF flow rate, and engine RPM.
Here's what I see:
At Idle, LTFT is high on both banks STFT is ok:
Does MAF flow rate look ok for idle? It fluctuates between 3.0 and 3.8, and when I search for what the number should be I get results that are all over the place - between 2 and 5.
Cruising in gear, things look much better:
Decelerating in gear is similar to idle, but not nearly as bad:
I've checked the above screens during a few drives, and they're repeatable, no anomolies. The high LTFTs at idle and decel in gear indicate to me that unmetered air is entering the intake system somewhere aft of the throttle body.
Note that before I captured this data, the MAF was cleaned and I cleaned/oiled the filter. I saw the same numbers prior to the cleaning. I'm always careful to not over oil the filter; I've been using K&N filters and intakes on various cars for ~20 years without oily MAF issues.
Things I have not done yet:
I have not pulled the engine cover to test for vacuum leaks underneath. I don't hear anything to indicate that there is a vacuum leak, but as we all know, the Coyote is noisy at idle.
I have not tested the EVAP purge valve.
I have the stock intake, but have not installed it. I will try this If I can't find anything wrong with the inake manifold or EVAP purge valve.
No smoke test yet, I'll need to buy/rent/build a tester for that.
Questions I have:
Does this look like a vacuum leak to other folks? From my searches here and other places, that's the common thread for these codes.
Does the MAF flow rate look right? I have never gotten a MAF-related fault code, so I doubt it's going bad unless it's doing so slowly.
Could it be the EVAP purge valve? This is another possibility from my searches, but again, no codes specific to it.
Any other thoughts? Where else should I be looking?
I don't want to throw parts at the car, and my emissions inspection isn't due until November, so no rush to solve this. I am getting tired of the CEL, though...
In the past couple of weeks, I've been getting the following DTCs: P0171 and P0174 (system too lean bank 1 and 2), usually occurring together. Other times I'll get P0420 or P0430 (catalyst below efficiency bank 1 and 2), but never at the same time. I'll clear the codes and be ok for a day or two before they come back, so before the readiness cycle completes. The car starts and runs fine both cold and hot and Idles around 640 RPM indicated on the dash. Occasionally the idle will dip when the fans come on (becaue Texas. AC is on 24/7) and other times throttle response can be a little sluggish off idle when I acclerate from a stop. This leads me to believe I have a vacuum leak somewhere, I just want to do a sanity check before I go down the wrong rabbit hole.
I've sprayed brake cleaner at all fittings between the MAF and throttle body, MAF included, while the car is running. Doing that has no effect on the idle speed, telling me that there probably isn't a vacuum leak between the MAF and throttle body. I plan to pull the engine cover this weekend and spray brake cleaner around the intake manifold fittings and fuel injectors and also test the EVAP purge valve (no EVAP related codes, though) for vacuum on the tank-side fitting.
I've logged PIDs looking at both short and long term fuel trims for both banks, MAF flow rate, and engine RPM.
Here's what I see:
At Idle, LTFT is high on both banks STFT is ok:
Does MAF flow rate look ok for idle? It fluctuates between 3.0 and 3.8, and when I search for what the number should be I get results that are all over the place - between 2 and 5.
Cruising in gear, things look much better:
Decelerating in gear is similar to idle, but not nearly as bad:
I've checked the above screens during a few drives, and they're repeatable, no anomolies. The high LTFTs at idle and decel in gear indicate to me that unmetered air is entering the intake system somewhere aft of the throttle body.
Note that before I captured this data, the MAF was cleaned and I cleaned/oiled the filter. I saw the same numbers prior to the cleaning. I'm always careful to not over oil the filter; I've been using K&N filters and intakes on various cars for ~20 years without oily MAF issues.
Things I have not done yet:
I have not pulled the engine cover to test for vacuum leaks underneath. I don't hear anything to indicate that there is a vacuum leak, but as we all know, the Coyote is noisy at idle.
I have not tested the EVAP purge valve.
I have the stock intake, but have not installed it. I will try this If I can't find anything wrong with the inake manifold or EVAP purge valve.
No smoke test yet, I'll need to buy/rent/build a tester for that.
Questions I have:
Does this look like a vacuum leak to other folks? From my searches here and other places, that's the common thread for these codes.
Does the MAF flow rate look right? I have never gotten a MAF-related fault code, so I doubt it's going bad unless it's doing so slowly.
Could it be the EVAP purge valve? This is another possibility from my searches, but again, no codes specific to it.
Any other thoughts? Where else should I be looking?
I don't want to throw parts at the car, and my emissions inspection isn't due until November, so no rush to solve this. I am getting tired of the CEL, though...
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