Longterm Fuel trim High at idle

[Rsalazar35SHO]

Is the PCV vent connector to the intake manifold sealing correctly? You would have found this with a smoke test already, but I was having an issue and located my problem there.

ill double check it, even though we smoke tested it, we still found boost leaks the smoke test didn't.

however I don't think the boost leaks were the problem since its at idle, when the engine is under a vacuum not boost.
it might be that seal.



recently when doing a boost leak test, I added about 8-10 PSI and right after I did this, the car was smoking terribly. this was due to that PCV on the valve cover not being the updated "green one". I have since swapped it out and no more smoking. but i wonder if that seal was bad on the actual intake and its allowing un metered air into the manifold.

 

[76FoMoCo]

Is the PCV vent connector to the intake manifold sealing correctly? You would have found this with a smoke test already, but I was having an issue and located my problem there.

This is how I solved it

 

[Rsalazar35SHO]

This is how I solved it.

did you just block it off completely ? lol


so i found a forum page with a guy having similar issues, check his last post in the thread and let me know if you think this could be my problem as well. if so ill buy the sensor, all the gaskets and try cleaning the intake valves once i figure out how.

 

[76FoMoCo]

did you just block it off completely ? lol


so i found a forum page with a guy having similar issues, check his last post in the thread and let me know if you think this could be my problem as well. if so ill buy the sensor, all the gaskets and try cleaning the intake valves once i figure out how.

Yep

 

[Rsalazar35SHO]

Yep

i think i'm going to pull the intake off, clean the mating surface and install fresh gaskets on it, then clean the valves with some wire brushes and see if this corrects the problem. ill try putting some rubber caps on those PCV outlets too and see if it does anything lol.



https://shoforum.com/threads/high-fuel-trims-and-intermittent-p0171.141164/page-2 -- this is the link for the forum with similar issues.

 

[Ta2dResqr]

i think i'm going to pull the intake off, clean the mating surface and install fresh gaskets on it, then clean the valves with some wire brushes and see if this corrects the problem. ill try putting some rubber caps on those PCV outlets too and see if it does anything lol.



https://shoforum.com/threads/high-fuel-trims-and-intermittent-p0171.141164/page-2 -- this is the link for the forum with similar issues.

You realize the valves are in the head and you will barely be able to see them through an intake passage correct? Beyond that you will only be able to access one small area of the valve. You will also need to rotate the motor in order to bring different cylinders to TDC to get to each valve. If you would like to clean them, I would suggest something like Sea Foam, Top Engine Cleaner, CRC GDI IVD (Intake Valve and Turbo) Cleaner, etc. After that, either a Oil Catch Can or Methanol Injection to keep them clean.

That being said, usually dirty valves are going to cause them to hang open resulting in an incomplete burn. This will result in a rich exhaust reading and the system pulling fuel to lean it out. You are experiencing the opposite. I suppose if it was pulling clean air into the exhaust during the intake stroke it may see to much air and add fuel. I would expect that more at higher RPMs/Boost though instead of at idle.

 

[Rsalazar35SHO]

You realize the valves are in the head and you will barely be able to see them through an intake passage correct? Beyond that you will only be able to access one small area of the valve. You will also need to rotate the motor in order to bring different cylinders to TDC to get to each valve. If you would like to clean them, I would suggest something like Sea Foam, Top Engine Cleaner, CRC GDI IVD (Intake Valve and Turbo) Cleaner, etc. After that, either a Oil Catch Can or Methanol Injection to keep them clean.

That being said, usually dirty valves are going to cause them to hang open resulting in an incomplete burn. This will result in a rich exhaust reading and the system pulling fuel to lean it out. You are experiencing the opposite. I suppose if it was pulling clean air into the exhaust during the intake stroke it may see to much air and add fuel. I would expect that more at higher RPMs/Boost though instead of at idle.

thats why i asked, thank you. idk i reach that older post about someone who did this, and went from 20%+ LTFT and did valve cleaning and intake manifold gaskets and fuel rail pressure sensor and got it to correct it. check his thread in the link i posted.


okay real questions here, does seafoam actually work at cleaning the valves ? I have heard yes and heard no.

anyone have a good catch can they recommend, I heard bad things about the JLT one.

 

[Ta2dResqr]

The best reviews I have seen have been on RXP. Of course that comes at a cost ($449+). Personally I have the JLT because I got it super cheap used. I would say it is better than nothing but not enough that I would have paid full price.

As far as Sea Foam, personally I have had great luck with it in many applications. I have recommended it to many friends, family, and co-workers with great results. From use in the fuel tank to free up secondaries on a carb, to running it through the oil to free up solenoids in an MDS system, to cleaning out intakes. To use it on our application for the purpose of cleaning valves, I would suggest the aerosol can and putting the nozzle in at the noisemaker pipe. This will prevent it from condensing anywhere in the intake tract before it gets to the throttle body/manifold.

If you plan to use the CRC cleaner, I would go through the air box as it is designed to clean the turbos as well and then through the noisemaker pipe.

You can also buy the combo pack with the aerosol and the liquid. Run the aerosol as described then dump the liquid into the fuel tank to clean up the injectors and pistons.

I do suggest doing this outside (not just with the garage open). It will smoke like crazy. It is also easiest if you have someone to help you. You will need to hold the car at a high idle while spraying it into the engine (about 7 minutes).

 

[Rsalazar35SHO]

when you say high idle, what RMP am I looking at? 3000, 4000? ill probably do the aerosol can I have the noise maker deleted on my SHO so no need to worry about getting I there and doing to much. perhaps ill see about getting a JLT if I can find one decently priced for the time being. like you said better to have one then none.

I have heard about turbo burn out with doing this seafoam is this something I should take note of an watch? maybe have some water sunning over the engine or a fan blowing cold air at the turbos (mainly the inside one). I just don't want to damage something else and make this a whole new can of worms.

 

[Ta2dResqr]

More like 2000 rpm. I have never put a fan on the motor. I usually do it on a cold engine which compensates for some of the time. Cooling fans should help with the rest. Check out their website. Lots of FAQ about use, and specific applications including GDI and EcoBoost.

 

[Rsalazar35SHO]

More like 2000 rpm. I have never put a fan on the motor. I usually do it on a cold engine which compensates for some of the time. Cooling fans should help with the rest. Check out their website. Lots of FAQ about use, and specific applications including GDI and EcoBoost.

dude you guys are awesome, ill give it a shot and see if it helps.

for the most part I think I'm going to try replacing intake manifold gaskets and clean um the patting surfaces pretty well and see if that helps.

luckily my guys at my local for dealership still give me employee pricing on anything. so that will help.

ill keep the thread updated on if this corrects my issue, I don't think it should take me very long to get the intake off and reinstalled. i think the coolant is the hardest pain in the butt. from what I have read.

 

[HellCow]

i think i'm going to pull the intake off, clean the mating surface and install fresh gaskets on it, then clean the valves with some wire brushes and see if this corrects the problem. ill try putting some rubber caps on those PCV outlets too and see if it does anything lol.



https://shoforum.com/threads/high-fuel-trims-and-intermittent-p0171.141164/page-2 -- this is the link for the forum with similar issues.

I knew it. More than likely its the fuel pressure sensor. I would bet $$ on it.

 

[Rsalazar35SHO]

So actually tested fuel level pressure with a ford IDS laptop and fuel pressure is perfect. Spoke to my tuner and he said it could just be at idle, when the car is under load fuel trim sits right at 3-5% where it should be. So idk lol I’m at a loss

 

[COMpulse]

My last car that had high fuel trims at idle was a leaking egr tube. But that was on an maf based car (gtp). I don't even know if the sho has egr, or if it would have the same effect.

 

[Rsalazar35SHO]

My last car that had high fuel trims at idle was a leaking egr tube. But that was on an maf based car (gtp). I don't even know if the sho has egr, or if it would have the same effect.

see and I thought it was a leaking canister purge valve, they fail all the time. sure enough min was bad, but I replaced it before I started having all these issues. its only at idle its high. if i do a hard pull LTFT goes to about 1.05 average both banks. STFT will read about .98 both banks average. for a total fuel trim of 3% which is average. but I can figure out this leak issue at all man. its driving me crazy.

my tuner said at idle its not gonna hurt anything being high, but under load is where we need it perfect. so I'm going to get the cold plugs back in it, 2.5Bar map and reinstall the base map and get some recordings over to him.

 

[COMpulse]

I think there are PIDs that will provide fuel trims for bank 1 and bank 2. Maybe those will help.

 

[Rsalazar35SHO]

I think there are PIDs that will provide fuel trims for bank 1 and bank 2. Maybe those will help.

we watched them at ford last night with some friends I have at a dealership. the were with in spec, its just running lean at idle and not throwing a code or anything for it since its below 20% which is fords acceptable spec.

 

[Rsalazar35SHO]

so update, got the car back on the Ortiz base map, no issues for a solid 24 hours.
this morning after about half throttle acceleration in 3rd P0131 P0151 posted on the CEL.

P0131-O2 sensor bank 2 sensor 1 low voltage.
P0151-O2 sensor bank 1 sensor 1 low voltage.

I was able to get them ordered Friday thinking they might be the problem. should be in today or tomorrow and then onto the car they go.

hopefully fuel trim stays right on target with these new O2 sensors and i can get back into tuning it more.

I appreciate everyone input and help. I'm going to keep the thread updated incase anyone else seems to have a similar issue and needs some place to look.

 

[Rsalazar35SHO]

update,

the o2 sensors did correct the codes i have been having P0131 and P0151, but still have high LTFT at idle, I'm going to start remvoing all the PCV lines on the intake 1 and a time and see if blocking that off changes anything.

 

[Rsalazar35SHO]

honestly at a, loss at this point, no more P0131 and P0151. however fuel trim is still high at idle but reaching perfect + or - 5%, fuel trim underload. idle is just high, which still makes me think its a vacuum leak, however cannot find it leaking from anywhere lol super frustrating.

I did check the intake vacuum hoses, by remove them one at a time and monitoring LTFT and STFT, they didn't give me the numbers i was looking for, but also didn't correct the problem. I'm going to boost leak test the system, put it under 8psi of compressed air and see if it finds any pin holes I'm loosing or pulling unmetered air in from.