LTFT at Idle. WTF?

[tatasta]

Hello

2010 L99, SLP S/C. 3.2", ZL1 pump, Jannetty FPCM, ID 1050X and JBA cat-delete mid pipes.

After injector, pulley size drop, ZL1 pump, FPCM and JBA cat delete install. LTFT at idle logs at Bank 1 0.92 and Bank 2 is 1.04 on SCT Livelink.

Quick rundown:
- O2 sensors are OEM and new.
- No exhaust leaks detectable.
- Ran two smoke tests and no vacuum leak found
- Trims are different by 10-12% at idle with Bank 2 being leaner (1.02)
- When driving and at normal throttle positions, the difference closes up to 2-4% with bank 2 usually showing richer.
- Tune done by Ted. The LTFT prior to the install of the parts listed above (just the standard SLP kit) was right on.
- Ted caught the issue on one of my logs and suggested an exhaust leak or vacuum leak. Which I expected to find.
- Have not been able to locate a leak with carb cleaner sprayed around the entire engine and two smoke tests.
- Re-gasketed and torqued mid pipes to exhaust manifolds.

How much air is getting by to cause a 10-12% difference between banks?

I am going crazy.

Anyone else dealt with this? Or, have advice on how to proceed?

Thank you

[Pro-tuned]

When you say 02 sensors which ones? Original for your year of car? Check header gaskets at both ends?

[tatasta]

Originally Posted by Pro-tuned

When you say 02 sensors which ones? Original for your year of car? Check header gaskets at both ends?

Hello,

Yes. They are the O2 sensors that match the VIN for the car. I have the cat-less JBA mid-pipes and stock exhaust manifolds for now. I have checked the connections. The stock manifolds have never been removed and I cannot detect any leak at the connection between the manifolds and the JBA pipes.

When I smoke tested the car I only used the ~1psi that the regulator on the smoke machine allows. Do I need to allow more pressure into the engine for the smoke?

Thank you for the response.

[tatasta]

When I log STFT, the values on both banks show between 0.98 and 1.01. Both banks stay within 2-3% of each other. However, the LTFT between banks has a delta of 10-12%.

Don't know. Guess I will do more work to find a leak this weekend.

Is it unsafe to drive the car?

Could I have done something wrong when installing the injectors?

[eLeSthree]

Originally Posted by tatasta

When I log STFT, the values on both banks show between 0.98 and 1.01. Both banks stay within 2-3% of each other. However, the LTFT between banks has a delta of 10-12%.

Don't know. Guess I will do more work to find a leak this weekend.

Is it unsafe to drive the car?

Could I have done something wrong when installing the injectors?

Yes, its possible. Did you put lube on the o-rings? did one tear? Did you accidentally leave one stock injector in? lol Is the fuel rail tightened down snug? Are you using injector adapters?

[tatasta]

Originally Posted by eLeSthree

Yes, its possible. Did you put lube on the o-rings? did one tear? Did you accidentally leave one stock injector in? lol Is the fuel rail tightened down snug? Are you using injector adapters?

Yep. I did lube the o-rings. I am pretty sure that I got all 7 of the new ones in there...

The fuel rail is torqued and no injector adapters.

Gotta be a leak somewhere. I will try again to find it.

Thank you

[JANNETTYRACING]

Originally Posted by tatasta

Hello,

Yes. They are the O2 sensors that match the VIN for the car. I have the cat-less JBA mid-pipes and stock exhaust manifolds for now. I have checked the connections. The stock manifolds have never been removed and I cannot detect any leak at the connection between the manifolds and the JBA pipes.

When I smoke tested the car I only used the ~1psi that the regulator on the smoke machine allows. Do I need to allow more pressure into the engine for the smoke?

Thank you for the response.

running a smoke machine in the engine can only find big leaks due to the low pressure.

We cap the TB and blow 10-15 psi in the intake to test all that.

The exhaust is a little harder to test but black soot trails are the first indication.

I would be looking at the Mid pipe to manifold connection by removing and looking for soot trails.

You can have a friend with welding gloves try and cap the tail pipes with the car running while you look around under the car for leaks near the O2 sensor.

A pin hole near the O2 sensor and really screw with the readings.

Ted.

[tatasta]

Originally Posted by JANNETTYRACING

running a smoke machine in the engine can only find big leaks due to the low pressure.

We cap the TB and blow 10-15 psi in the intake to test all that.

The exhaust is a little harder to test but black soot trails are the first indication.

I would be looking at the Mid pipe to manifold connection by removing and looking for soot trails.

You can have a friend with welding gloves try and cap the tail pipes with the car running while you look around under the car for leaks near the O2 sensor.

I pin hold near the O2 sensor and really screw with the readings.

Ted.

Great info. Thank you, Ted. What do you use to cap the TB that can stay on with 15psi against it? My rubber glove won't quite handle that.

Thanks again!

[JANNETTYRACING]

Originally Posted by tatasta

Great info. Thank you, Ted. What do you use to cap the TB that can stay on with 15psi against it? My rubber glove won't quite handle that.

Thanks again!

4 inch Plummers cap, Air fitting, Silicone boost hose, and T-bolt clamps.

Ted.

[Pro-tuned]

Originally Posted by JANNETTYRACING

running a smoke machine in the engine can only find big leaks due to the low pressure.

We cap the TB and blow 10-15 psi in the intake to test all that.

The exhaust is a little harder to test but black soot trails are the first indication.

I would be looking at the Mid pipe to manifold connection by removing and looking for soot trails.

You can have a friend with welding gloves try and cap the tail pipes with the car running while you look around under the car for leaks near the O2 sensor.

I pin hold near the O2 sensor and really screw with the readings.


Ted.

Well said! Ted you should have been a Phycologist...

[JANNETTYRACING]

Noticed a typo in the last sentence was suppose to be:

A pin hole near an O2 sensor can really screw with the readings.

[tatasta]

Originally Posted by JANNETTYRACING

4 inch Plummers cap, Air fitting, Silicone boost hose, and T-bolt clamps.

Ted.

Perfect. Thank you!

[tatasta]

Just an update.

Resealed both of the mid-pipes to exhaust manifolds. Checked that the O2 sensors were sealed and searched for vacuum leaks.

After this, LTFT at idle are Bank 1 0.90 and Bank 2 0.98 on SCT X4.

Do those number give an indication which side likely has the leak? And, any clue to if it is on the exhaust or intake side?

Thank you