HI All,

First off this is for my street car.

Just built a new engine: twin turbo small block Ford running on E85. Started it for the first time yesterday after over a year in the works.

Engine started up on the 3rd revolution and seems to run fine. Problem is the A/F is .8-1.5 leaner on one side than the other at idle and cruise and it stays pretty consistent there. Didn't really get into boost because I have to tune it and it was raining when I took it out yesterday.

During the build I installed 2 new wideband sensors (one in each down pipe), had injectors sent out to have cleaned and tested.

On the lean side I did the following: installed new plugs, checked the spark plug wires, checked the valve lash (solid roller). I also swapped the 02 sensors from bank to bank, swapped wideband controllers from bank to bank, next swapped fuel injectors from lean bank to rich bank and injectors from rich bank to lean bank. After all the changes the A/F didn't change at all. Bank is still lean all over. I also tested the intake on the outside for leaks. Did a compression test on all cylinders- all within 7 psi.

The only thing I can think is an internal vacuum leak on the intake or a problem with the ECU that I have been using prior with no issues. I was also going to do a leak down test.

Does anyone have any other ideas?

Use propane to find any vac leaks as you can see the AFR possible change.

How is the exhaust set up - do you have anything possible going on with that. Are both O 2 s installed in the exact location and depth - per each side ??

Intake issue ? air and or fuel distribution. Any port work ??

The other thing that I can really think of is your FUEL INJECTOR(s) extenders / O ring seals possible NOT SEALING GOOD causing air leak(s). I have seen this exact issue before.

Injectors sitting and not balance flow volumes after the fact ? .

Give me a call if you want to - we have nt talked in a while anyways THANKS

injector install did you lube the orings before the install ? Just asking

Hi John, long time no talk!!!

Used propane over outside of intake/vacuum lines to look for leak. Found none.

Checked exhaust for leaks, found none. Exhaust has v band flanges from the turbos back to the rear or the doors than out to full tailpipes.

02 sensor locations are within a foot of each other. Far away from the turbos to over heat.

No new port work on intake. Heads were just freshened up by top head guy.

Injector o rings were lubed. Also swapped all injectors from bank to bank, no change. That was my first thought, problem with an injector. Absolutely no big change in A/F after swap. That shoots down that thought.

With engine running I pulled one injector clip off at a time. Got a very slight rpm change each time.

Engine probably has 1 to 1 1/2 hours run time now. This is really driving me nuts.

John give me a call when you get a few minutes. I know you're very busy.

which bank is lean and what efi system are you using?

Injector port itself ? maybe not a good sealing injector port on the lean side of that bank ?? Just throwing out ideas.

Like above said as a possible good idea swap the Turbos.

wonder if the turbos could be causing an issue like that as that would be a good test to see if it had to be ruled out or as the issue

Thanks for the help so far everyone!!!

I talked to someone a lot smarter than me(actually that is most people). He had a few ideas. He said swapping turbos was a good idea. They are cast housings and might flow differently. Said he seen it before. Good call Hogie!!! I never would have thought of that.

I really only idled and brought it up to 3000rpm under light load, plus brought it up to about 2-3lbs of boost for a split second (still needs tuning). He said bring it up to 4000-5000rpm and load and see if it gets any closer. Will try this next.

Next my Down pipes are different. The leaner side has one 90 bend right out of turbo. The richer side has two 90 bends right out of turbo. This could be causing a bit more back pressure on the one bank. I think this could be the cause.

I am going to try swapping the turbos and if nothing changes check back pressure before the turbos to compare.

He had another idea but I'll hold that for now.

I wish I could post pictures but site won't let me.