The Val

[VNracer34G]

Awesome work !
Just enough alright so what size injectors next?
I'd be suspcious of your runners and plenum for the mixture distribution - i take it you would have swapped the injectors side to side to see if it made a diference.

[VL400]

Will try a small fuel pressure increase before replacing them, they are 42lb at approx 50psi (or might be 55psi) base pressure so there is a little left in them yet.

Will swap injectors left to right and see if it makes a difference to the AFR. Need to get 8 O2s on there and see if its all or just a couple of cyl that are lean

[yoda69]

Alternatively 8 cheap temperature probes.

[VL400]

Yeah thats always an option, much cheaper than 8 widebands! Will swap injectors for the next meeting and see what happens.

New PB now, 10.04 @ 131.7MPH

[Jayme]

wow go the 9! surely 5 hundredths is possible

[VL400]

We are hopeful!

[heff0018]

What happened with the val? This story was really interesting but then just stopped

[Tre-Cool]

Had a test and tune day and decided to make the most of the logger and run a wideband in each bank. If only it was running a VR PCM or later seq PCM to sort the imbalance out! At the worst point there is an easy 0.5 to 1 AFR difference. We did swap widebands and the lean side was always the drivers side.

Dual Wideband.png

I have a similar problem with my dads drag car, but it seems to be only under certain rpm and boost conditions.

I suspect its actually a earthing/voltage problem. It has a dual sensor haltech unit.

my drag car is a similar combo, so I used his tune as my base before I started adjusting and ran pretty much similar times at 9.5/6 with less boost. Yet my widebands from side to side were the same.

during the off season im going to remove some of the old wiring from it along with new alternator pulley tensioner as the voltage is dropping from belt slip down in to the 11v range

Could you be having a similar problem?

[immortality]

Is there a balance pipe in the exhaust?

Delco had similar issues on a 304 with dual exhaust, fitting a balance pipe evened out the AFR's.

[delcowizzid]

yeah balance pipe smaller than exhaust diameter in the hot spots on the exhaust helped the 304 tremendously for cylinder variation