LEAN on both banks

[cadman777]

Hi RichLo,

Thanks for the advice.
Today I ordered the parts, and will install them when they arrive.
Then the guy can run it for a week or so.
Then back to me to check on it.

I could not find any replacement parts for the intake leak.
Maybe you know a source where I can get them?
It's a 1998 Tahoe 5.7L Vortec intake adapter that mounts to the throttle-body.

I've done that (bringing everything back to OEM spec) on a badly butchered 2000 Silverado LS1 V8.
Did that 5 years ago, and the thing keeps on running and running w/o problems.
But this guy is different.
My thought was to get O2 emulators for the aft O2 sensors and get a guy to do a PCM update for the EGR system and tune it to the cam.
But first I need to learn the procedure for determining what cam is in it.
Not sure how to do that.

I think when the new plugs arrive, that'll fix the #3 mild misfire.
As for the intake adapter leak, I bought a couple Buna-N square seals that I can super-glue together so they will fill into that hole AND seal. But that's not as secure as the rubber-coated metal double lip seal that came from GM. Anyway, hopefully that'll fix the leak.

Cheers...

 

[RichLo]

Are we talking about just the Throttle body to intake manifold gasket like this...?

More Information for FEL-PRO 61036

Or Does it have a spacer in between like this...?

More Information for SPECTRE PERFORMANCE 11257

If it has the spacer, you could just order another one from above as its only $30. But if your having problems with it sealing I would eliminate that also. Just bring it back to OEM w/o the cheap spacer. And get a fresh Fel-Pro TB-to-Mani gasket just for good measure (for a whole $3.59)

 

[RichLo]

And for the cam specs, Shurkey will probably tune back in but I assume he is talking about putting a degree wheel on the harmonic balancer like this...

Summit Racing SUM-G1057-16 Summit Racing™ Cam Degree Wheels | Summit Racing

Free Shipping - Summit Racing™ Cam Degree Wheels with qualifying orders of $109. Shop Degree Wheels at Summit Racing.

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Then taking the drivers side valve cover off and setting up a couple magnetic mounted micrometers on the rocker tips of the int and ex valves. With patience, lots of notes and multiple rotations you can get very close to figuring out all of the cam specs. Or at least all of the cam specs that matters to an engine computer tuner.

 

[cadman777]

RichLo, thanks for that cam spec advice.
I await intstructions from Shurkey.

As for the seal, it's this one:

You must be registered for see images attach

 

[Erik the Awful]

Yeah, those seals are "no longer available". Instead of cutting and superglueing, you can probably take it to a local seal supply company and get the correct one for less than a $10 bill.

It ain't my vehicle.
I know for a fact that the owner ain't gonna add EGR and cats.
So I gotta work with what I got.

No, you don't. You can tell him to take a hike if he's not going to fix it right. I understand there might be a family or friendship dynamic, but sometimes you gotta be honest with them. With the factory injection and tune, I would insist on fixing the EGR.

The engine that's currently in my Stepside was originally built for my '99 Suburban. It has a very healthy cam that requires a tune, but even without a tune it ran smooth. The Vortec moved enough air and fuel that I could give it full throttle and it wouldn't misfire. The TBI could handle half-throttle, and above that it didn't misfire, but rather tried to stall right out. The cam is not the cause of your misfire.

 

[cadman777]

Thanks for that info Eric.
I'll definitely take that under advisement.
Experience is always better than theory and 'opinion'!

The only other places I could think of that may be causing the LEAN signal (air leak) are:
1. EGR system
2. EVAP system
3. Brake booster
4. PCV valve
5. Intake manifold leak.
#5 is what worries me.
I read in another forum that these 350's are notorious for intake leaks.
I already unplugged the Brake BOoster and plugged the vacuum line, and that didn't make any difference.
It can't be the EGR system b/c that's plugged at the manifold and I checked the the valve and it's 'good'.
It can't be the EVAP b/c I tested those solenoids with the scan tool by actuating them.
Engine began misfiring when opening them till it died at around 90% open.
So today I'm going to check the PCV valve.
Otherwise, what else can be causing it?
If I smoke test the intake again then there should be no smoke coming out of the crankcase at the Oil Fill Tube, provided that I unplug the PCV valve and cover the end of it, and unhook the breather line that goes into the intake duct and plug it, right?

 

[0xDEADBEEF]

I can't tell you what it is from here, but an intake leak shouldn't make it lean on the O2 and rich to the nostrils. I'd expect a code about the MAF to be thrown too since it's getting air that isn't being measured.

Air is getting into the exhaust somehow. I'd be looking at exhaust leaks upstream from the O2, ignition, and the injectors.

 

[cadman777]

I can't tell you what it is from here, but an intake leak shouldn't make it lean on the O2 and rich to the nostrils. I'd expect a code about the MAF to be thrown too since it's getting air that isn't being measured.

Air is getting into the exhaust somehow. I'd be looking at exhaust leaks upstream from the O2, ignition, and the injectors.

Thanks for those ideas.
What's "nostrils"?

Yes, 4 of the plugs were backed out (not all the way screwed in) until I fixed that.
So 'ignition leaks' are now fixed.
That was a double-whammie, since the spark was buried in the threaded hole, instead of burning inside the combustion chamber.

Both header/head-pipe gaskets were leaking when it arrived.
So I fixed that too.

No MAF code, which brings me to another point:
Can someone in here post a list of known good DataStream at idle, at WOT, and under load?

I have no idea what they're supposed to be, so there's no way I can tell if sensors and feedbacks are in the proper ranges.
That's the one thing I absolutely HATE about 'digital' engines!
That's part of the long-term coup against American liberty/God-given rights.
(Communist manifesto: "Control of the means of production and means of distribution.").
If you don't PAY the monopolies, then you can PLAY in the repair game.
Everything today is a G.D. GAME!
People like me who hate gaming are lost in this wicked world that's tyrannized by the "idle rich".
Anyway....

I checked for vacuum at the valve covers, and nothing.
So there's no vacuum in the crankcase.
PCV valve is nearly new, so that's not a problem.

Only thing left is:
1. Intake manifold
2. Injectors

I would just HATE to remove the intake plenum only to discover that it's 'all good'.
Most of this was upgraded not too many years ago, so just about everything is checking out good.
It probably just needed a tune-up and some tweaking like I've already done.

I just want to see those data stream numbers...

 

[0xDEADBEEF]

Thanks for those ideas.
What's "nostrils"?

The 2 holes in your nose.

The computer sees too much O2/air in the exhaust, so it starts adding fuel, but since the problem wasn't actually from the engine running lean the problem doesn't go away.

 

[cadman777]

Haha, I get it.
A little slow on the update!

OK, I get that the mechanical causes prompted the computer to dump fuel into the cylinders (esp, Bank2)
But does the LEAN indicator in the EngineData mean it's running lean?
If not, then what's the purpose for it?