Vortec 454/4L80e HD swapped 1999 Tahoe OBS

[bigfootchiro]

If I'm you, I'm looking for a fuel problem on bank 2 for starters.

Only thing fuel related on Bank 2 specifically would be injectors then, correct? Maybe O2?
Keep in mind, this is a 454, and is not like the injector setup on the 350s.

 

[randeez]

could be ...engine usually runs in open loop when first started (not looking at o2 sensor) that could be why when you turn it off and back o nit runs fine

 

[bigfootchiro]

could be ...engine usually runs in open loop when first started (not looking at o2 sensor) that could be why when you turn it off and back o nit runs fine

So funny you say this, because it made me look at the readings at cold startup... as soon as it hit 110 degrees, the O2 sensors start kicking in. What do you make of this? Bank 2 LTFT 5.5% at start and big differences in voltages

 

[swathdiver]

So funny you say this, because it made me look at the readings at cold startup... as soon as it hit 110 degrees, the O2 sensors start kicking in. What do you make of this? Bank 2 LTFT 5.5% at start and big differences in voltages

View attachment 225239

You're narrowing it down, good thinking and observations. Now, what do those two mean? Too rich, not getting the cats hot enough? Or the opposite, I always forget which is which, like these <> in math!

 

[bigfootchiro]

You're narrowing it down, good thinking and observations. Now, what do those two mean? Too rich, not getting the cats hot enough? Or the opposite, I always forget which is which, like these <> in math!

Damn math. I used to be good at it! Positive numbers mean lean condition, like vacuum leak, clogged injectors, not enough fuel, etc. Right now I have no cats, and practically no exhaust lol. Pipes are dumped right next to the transmission.

 

[randeez]

that bank 2 sensor is way to low they should oscillate from like .700 to .999

 

[swathdiver]

Alright so you're lean on that side for some reason, O2 sensor is not getting as hot as the other side.

So what can cause this? Leaks, cracks, crimps, air, fuel, shorts to ground? Fuel getting to both sides of the rail evenly? No pipes crushed? Injectors good and nothing falling off them or has fallen into the hole they drop into? Intake gasket good, no cracks or leaks on that side, head gasket, intake gasket, intake manifold, cylinder head? Plugs screwed in all the way and firing? Not stripped and leaking? Rockers, valve seals...

 

[RST Dana]

Maybe swap injectors from one side to the other? See if the issue changes sides as well.

 

[bigfootchiro]

Alright so you're lean on that side for some reason, O2 sensor is not getting as hot as the other side.

So what can cause this? Leaks, cracks, crimps, air, fuel, shorts to ground? Fuel getting to both sides of the rail evenly? No pipes crushed? Injectors good and nothing falling off them or has fallen into the hole they drop into? Intake gasket good, no cracks or leaks on that side, head gasket, intake gasket, intake manifold, cylinder head? Plugs screwed in all the way and firing? Not stripped and leaking? Rockers, valve seals...

I would sure hope it’s not a head or valves... that’s what happened last time to the 350! Intake gaskets are all new, but doesn’t mean they aren’t leaking. There’s definitely a lot it could be, so time to start narrowing it down! Thanks man!

Maybe swap injectors from one side to the other? See if the issue changes sides as well.

That’s a good idea too. I’ll have to try that. Just swapped the O2 sensors around to see if it follows. Here we go!

 

[bigfootchiro]

Initial startup after O2 swap over. Long term in 2 is still 5.5 but 1 is 3.9.

Mid-warmup: as soon as O2 sensors go into closed loop (around 110), Bank 2 starts shooting up quickly to 25%. Short term on 2 is still not the greatest.

Full warm up: short terms stabilize, long term on 2 is still 25%. When RPMs go up to around 1800-2000, Long Term on 2 drops to around 9-10. Hit it with a load after that and it goes up to around 12.5%. Also, STFT on 2 is pretty erratic. It will stabilize, but say I come down to idle in Park or moving, it will go up to around 9-11%, then take about 10-20 seconds to stabilize, whereas Bank 1 stabilizes immediately

 

[bigfootchiro]

Does anyone know what this hose is called? It connects right behind throttle body on passenger side into valve cover. It isn’t seating properly in valve cover or intake. Can’t seem to find it anywhere online, and parts stores can’t figure it out.

 

[swathdiver]

My LTFTs at idle go up too when idling a while. Sometimes even into the high teens but once underway and at a steady speed they'll return to zero. So don't yet to be concerned about Bank 1, but do find that problem with Bank 2. Minus 25 is usually a massive vacuum leak, or maybe an exhaust leak of some kind on that side.

 

[swathdiver]

Does anyone know what this hose is called? It connects right behind throttle body on passenger side into valve cover. It isn’t seating properly in valve cover or intake. Can’t seem to find it anywhere online, and parts stores can’t figure it out.

View attachment 225266

View attachment 225267 View attachment 225268

That would have to be some part of the pcv system no?

 

[bigfootchiro]

That would have to be some part of the pcv system no?

That’s what I thought, but no one can find the part. I’ve seen 6.0 and 5.3 call it something like a Fresh Air Hose, but can’t find it for the 454

 

[swathdiver]

That’s what I thought, but no one can find the part. I’ve seen 6.0 and 5.3 call it something like a Fresh Air Hose, but can’t find it for the 454

http://www.irv2.com/forums/f22/positive-crankcase-ventilation-62121.html

See if you can find a VIN for a truck that came with that motor and run it through AC Delco's website.

https://parts-catalog.acdelco.com/catalog/catalog_search.php

Do you know the RPO and year of that motor?

 

[bigfootchiro]

http://www.irv2.com/forums/f22/positive-crankcase-ventilation-62121.html

See if you can find a VIN for a truck that came with that motor and run it through AC Delco's website.

https://parts-catalog.acdelco.com/catalog/catalog_search.php

Do you know the RPO and year of that motor?

I don’t know the RPO, but it’s a 1998. There’s an error in the VIN number somewhere too, just can’t find it

 

[swathdiver]

I don’t know the RPO, but it’s a 1998. There’s an error in the VIN number somewhere too, just can’t find it

Ok, I reckon it's an L21 which was the commercial version of the L29 Vortec 7400. Forged crank and pistons. So now you need the book on the L21 and then you can find that part or at least know where to look for it in boneyards. It was used in those P12/W-20 chassis you pulled it out of and the Kodiak, Topkick and H-Series Isuzu.

 

[bigfootchiro]

Ok, I reckon it's an L21 which was the commercial version of the L29 Vortec 7400. Forged crank and pistons. So now you need the book on the L21 and then you can find that part or at least know where to look for it in boneyards. It was used in those P12/W-20 chassis you pulled it out of and the Kodiak, Topkick and H-Series Isuzu.

It came out of a P30 chassis, and I did find the VIN! It’s VIN J, but don’t know if that specifies L21 vs L29. Still can’t seem to the part through AC Delco. I’ll look into the P21 and see if it matches up. Anywhere I can find the RPO codes online with the VIN? GM wants $50 to do the build sheet

 

[Tonyrodz]

It came out of a P30 chassis, and I did find the VIN! It’s VIN J, but don’t know if that specifies L21 vs L29. Still can’t seem to the part through AC Delco. I’ll look into the P21 and see if it matches up. Anywhere I can find the RPO codes online with the VIN? GM wants $50 to do the build sheet

Why so much?

 

[bigfootchiro]

So it is an L29 block. The L21 did come in the P12 chassis, but it has a coil near plug distribution, which mine doesn’t have.