Wiring checked. Engine in. B1 02 error - lean. eeHack log attached. Paying bounty!

[steveo]

isn't your MAF airflow fairly low for an idling 383..?

[kur4o]

First you need to find out if the lean condition is real or fake. I have seen coolant fouled 02s reading always lean and mpg of around 2mpg.

Idle MAP is fairly high around 50-53kpa range. With low maf readings and engine speed is always higher than commanded might suggest a vacuum leak. Engine sucking unmetered air.
Bad tune is always possible reason.

Start playing with mode 4 control and you will nailed it pretty fast. Start by going open loop and monitor O2s reading, than start increasing aft target and monitor at what value 02s goes to 700-800mv.

Than you can play with cylinder deactivation. If there is no change in map and rpm when you disable a certain cylinder, it might be a suspect.

[atlantadan]

I want to say that you all are f-ing awesome for helping. This engine has been kind of a bear and I while I thought I knew what I was doing, its obvious that there still is a hell of a lot to learn. Thanks for your patience.

i'd say first check for a bigass vacuum leak, loose intake elbow clamp after the maf, stuff like that. try plugging off every single vacuum port on the intake manifold except the FPR and spray around for an intake leak. isn't your MAF airflow fairly low for an idling 383..?

Yes, I would think so, after looking at it. So that would be another pointer to a vacuum leak? I pulled everything off and checked with carb cleaner. Idle did not change, so if its leaking - it is in the valley.

First you need to find out if the lean condition is real or fake. I have seen coolant fouled 02s reading always lean and mpg of around 2mpg.

Swapped 02's and the problem stays on bank 1

Idle MAP is fairly high around 50-53kpa range. With low maf readings and engine speed is always higher than commanded might suggest a vacuum leak. Engine sucking unmetered air.

There's another vote for vacuum leak. Y'all are convincing me to pull the intake, and then re-install my original one to test.

Start playing with mode 4 control and you will nailed it pretty fast. Start by going open loop and monitor O2s reading, than start increasing aft target and monitor at what value 02s goes to 700-800mv. Than you can play with cylinder deactivation. If there is no change in map and rpm when you disable a certain cylinder, it might be a suspect.

I monkeyed with cyl deactivation as suggested and they all seemed to have the same effect: RPM's drop a bit each time. I don't know anything about Mode 4 control....

More testing today:
- Swapped injectors from one side to the other: No change.
- Swapped 02's from side-to-side (second time): No change.
- Used IR temp gun on headers. Found that 3 cyls on bank 1 are colder than bank 2 - which points to poor/incomplete combustion. Chose the coldest port from Bank 1 and the hottest port from bank 2 and pulled the plugs. Ran a compression test on those two cylinders and they were identical @ about 200 psi.
- Plug pulled from cold side was gray/brown. Plug pulled from hot cylinder was black, which indicates that its running super duper rich.

[kur4o]

I think that you will need a new tune with that intake manifold.
Individual air to cylinder passage are different by stock manifold.
Edelbrock must flow much more air than stock and the individual cylinder trims are off the chart.

Mode 4 control allows you to control realtime how the engine runs.
You can force open loop while the engine is running or change spark advance.
I advice you to start playing by that and see if the lean conditions exhibits only at closed loop.
Hint. Warm the engine, switch to open loop and lower the afr value, while monitoring 02s.

You might post your current bin too.

[Terminal_Crazy]

Haha. That’s why i asked about the manifold!
Yes i had issue (may still have) with the Edelbrock LT4 manifold.
I remachined both faces as it was sucking air from underneath the ports.
I even bought the tool to measure the head face angles and the manifold angles. The manifold was off quite a bit.
I think i milled something like 0 to 0.007 top to bottom off both faces.
Also check front and rear china walls that it’s not sat up on them.

I am a bit dissapointed in the quality of the manifold
I also drilled out one of the front idle ports as it’s smaller than the others.
I could be wrong but I feel these ports could need to be bigger.

Oh and again BLM’s are maxed on both sides.



Mitch

[atlantadan]

I think that you will need a new tune with that intake manifold. Individual air to cylinder passage are different by stock manifold. Edelbrock must flow much more air than stock and the individual cylinder trims are off the chart. Mode 4 control allows you to control realtime how the engine runs.

Thanks for the info. Yeah, I am starting to think this Edelbrock LT1 manifold may be the source of my ill's. I swapped over the OEM throttle body and it had no affect, so the 58mm one is back on there for now

Haha. That’s why i asked about the manifold! Yes i had issue (may still have) with the Edelbrock LT4 manifold. I remachined both faces as it was sucking air from underneath the ports.

Thanks Mitch - you may have hit the nail on the head. I got the OEM intake off the shelf and started cleaning it up for re-installation within the next few days. We will see what sort of effect that has on all of this.

[steveo]

never used the edelbrock manifold, but in all my years of dealing with LT1 engines i've only heard of headaches, never any benefits

[Terminal_Crazy]

Easiest way to check the manifold when you clean it up...
check it's not sat on the front or back walls.(verylikely not as it will be sat up on the port faces.

lay 4 strips of some plumbers solder (about 2-3mm in diameter) across the port openings then snug the manifold down with a few bolts.

When you lift the manifold, measure the solder at the top & bottom of each port opening front to back.
There will probably be more clearance on the bottom. You are supposed to have a small clearance up at the top so the bottom fits in and the top is pulled up to the port faces.

You could try pumping propane into the valley through the rocker cover and watch the O2's/BLM's drop if it is sucking under there.

Good Luck
Mitch

[steveo]

I will pay a bounty to anyone that figures this out

steveo
i'd say first check for a bigass vacuum leak

cough cough ...

[atlantadan]

cough cough ...

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