Split LTFT - 15% Split

[ChaosActual]

Just finished with a compression test.. All cylinders were quick to build compression and are within 10% of each other. I honestly have no idea what it could be anymore.

Compression test results:

Cylinder 1- 168
Cylinder 2- 172
Cylinder 3- 164
Cylinder 4- 176
Cylinder 5- 164
Cylinder 6- 166
Cylinder 7- 166
Cylinder 8- 163

[sixty9fordkiller]

i still say you need to do a smoke test.

could be leaking from the brake booster port
could be leakinf from MAP sensor port
...........

could be leaking from the pcv port on the valve cover....

....etc. I still think you have a vacuum leak since you said that adding fuel didnt change anything

[ChaosActual]

Originally Posted by sixty9fordkiller

i still say you need to do a smoke test.

could be leaking from the brake booster port
could be leakinf from MAP sensor port
...........

could be leaking from the pcv port on the valve cover....

....etc. I still think you have a vacuum leak since you said that adding fuel didnt change anything

The troublesome part is that most vacuum leaks would cause a lean condition but it would be distributed throughout both banks. Not many things I can think of that would only cause bank 2 to run lean other than an exhaust leak or intake manifold gaskets specific to that bank. Not to mention the plethora of other parts I’ve swapped out that *could* contribute to it. Regardless, a smoke test won’t hurt and will likely be my next purchase.. Just figured I’d do a compression test first since it’s a free and easy way to check for any valve issues.

[sixty9fordkiller]

Originally Posted by ChaosActual

The troublesome part is that most vacuum leaks would cause a lean condition but it would be distributed throughout both banks. Not many things I can think of that would only cause bank 2 to run lean other than an exhaust leak or intake manifold gaskets specific to that bank. Not to mention the plethora of other parts I’ve swapped out that *could* contribute to it. Regardless, a smoke test won’t hurt and will likely be my next purchase.. Just figured I’d do a compression test first since it’s a free and easy way to check for any valve issues.

a vacuum leak at the brake booster port or at the MAP sensor port will cause a lean condition on both banks.

a bad brake booster will cause it too


smoke it!

[ChaosActual]

Originally Posted by sixty9fordkiller

a vacuum leak at the brake booster port or at the MAP sensor port will cause a lean condition on both banks.

a bad brake booster will cause it too


smoke it!

Just bought a smoke machine after my last post. I’ll report back on Saturday after it is delivered.

[sixty9fordkiller]

perfect example right here....


https://youtu.be/3BquA8x4LMU

[InFiD3ViL]

Originally Posted by sixty9fordkiller

perfect example right here....


https://youtu.be/3BquA8x4LMU

That was a great watch, thanks. I have watched him for a while. He is a true mechanic. He also has amazing electrical troubleshooting skills. It is crazy how many other shops send their work to him.

[eLeSthree]

Could be an injector o-ring. I know you went over the exhaust already, but I had to weld a 3 bolt flange onto my tsp headers to get them to seal up tight.

[ChaosActual]

Originally Posted by eLeSthree

Could be an injector o-ring. I know you went over the exhaust already, but I had to weld a 3 bolt flange onto my tsp headers to get them to seal up tight.

Already replaced the injectors. I also removed the connection pipe entirely and welded in a pipe. I’ve checked and double checked the exhaust for leaks by pressurizing it with a few psi of air and listening, spraying soapy water, and looking for leaks. Used the same method for finding the leak the first time and it was very effective. I’ll probably smoke the exhaust just to double check when my smoke machine is delivered this weekend.

[John_C]

I'm having the same issue.

Cylinder imbalance codes both banks.
Lean codes both banks.

Already did new O2's...

Going to try and weld in some Vbands at the header collectors and mid pipes to see if that solves it.

[CamaroBarb]

Exhaust temps are very important to diagnosing this. 4 cylinders are feeding the O2 sensor so all 4 get the same change in LTFT. But usually only 1 cylinder needs it, checking the exhaust temps should tell you what cylinder is causing the problem.

[ChaosActual]

Originally Posted by sixty9fordkiller

smoke it!

Smoke machine got delivered early so I spent the last hour smoking it. Plugged the intake with a PVC cap and tried 3 different access points. I found a very micro leak under the intake to filter clamp. Tightened it up and solved that one. No other leaks found.

Also tried smoking the exhaust and didn’t see anything. I then pressurized the exhaust with a few psi of air and soaked the whole thing from headers back in soapy water to check for any leaks... Nothing.

Originally Posted by CamaroBarb

Exhaust temps are very important to diagnosing this. 4 cylinders are feeding the O2 sensor so all 4 get the same change in LTFT. But usually only 1 cylinder needs it, checking the exhaust temps should tell you what cylinder is causing the problem.

I’ve tried that but with having header wrap I was having a hard time getting consistent readings with my IR heat gun. I’ll give it another shot though.

[eLeSthree]

https://forum.hptuners.com/showthrea...s-bank-to-bank

[John_C]

Keep us posted.

This issue is driving me crazy on my junk, too.

I have my widebands reading Lambda and mine likes to swing as high as 1.10 lambda just like yours.