5.3 Problem

[POWERZONE]

I had a conversion car come in that is a bit of trouble. Maybe you guys can see something I don't or confirm.
Here is the info on the car-

79 Malibu
All Stock 5.3 from a 2005 Silverado
4L60E

Diagnostics findings:
-The LTFT immediately shoot to +25 Bank 1
-I get P0171
-P0300 sometimes
-I checked misfire tables and #6 has the most misfire and #5 a few(#5 misfires go away with rpm). The #6 misfires increase with rpm. All other cylinders have no misfires
-spark plugs are black
-O2's are black
-I retorqued the intake bolts correctly.

Note:
The owner put blue rtv sealer around the intake gaskets. I asked him about it, he said his mechanic suggested that he do that.

Of course I am thinking vaccum leak some where maybe. The none responsive O2 has me thinking something else maybe.



What do you think?

[Road]

Wiring to O2 sensors. Bank1 wired to bank2 ect....?

[POWERZONE]

Wiring to O2 sensors. Bank1 wired to bank2 ect....?

I have to download the wiring manual off painless. This is the times when tuning is a pain. I m one of the few tuners that will actually do some wiring investigation or wrenching around here. Most shops won't touch it unless it is 100% ready to go. I guess I am not that famous or big time yet. LOL

[Road]

If it's a painless then is most likely wired wrong. Nobody wants to work anymore...

[POWERZONE]

I swapped sides and it works. The only problem now is the O2 is reading lazy or dead at idle but switches well under rpm. I ohm'd 2 different AC delco O2's and they both ohm's fine at 15. I checked the power and ground on the O2's harness connector (C and D terminals) and they both read 12.4.

B1 Now is switches immediatley in closed loop. B2 takes a while to finally starts switching. We even tried 2 different new O2 sensors.

What would make this one side lazy but switch under load only?

[cesar]

Spray some carburant around the intake to confirm vacuum leak. Weld a bung in the lazy O2 bank to confirm lazy switching with a wideband. You can try and mess with some of the parameters in the closed loop section such as the proportional idle thresholds, the airflow values and take a look at the closed loop integrator delay>O2 error.

[POWERZONE]

When the B2 O2 harness plug was on the drivers side wrong, we got P0171(bank 1 lean, the drivers side). We swapped the B2 O2 harness to the correct side, the passenger side and now we are getting P0174. So where ever we are going with this one O2 harness connector, we get lean readings. We have swapped several O2's and it the same, dead at idle but switches once rolling. We even swapped it back to the drivers side just to see and here comes P0171.

Do you think its something computer related(bad ground or heater processing) or possible a bad O2 connector on the harness?

No headers, no cats, stock manifolds.

[Road]

From the log it looks to me like the O2 sensors are slow to respond. Sound like you have eliminated it being a sensor or O2 heater control issue. How far are the O2 sensors from the manifolds? Being catless and sensor location... you could try forcing the O2 proportional to oscillate faster.

[POWERZONE]

From the log it looks to me like the O2 sensors are slow to respond. Sound like you have eliminated it being a sensor or O2 heater control issue. How far are the O2 sensors from the manifolds? Being catless and sensor location... you could try forcing the O2 proportional to oscillate faster.

I usually do not run into an issue like this or have to increase the proportional to oscillate faster with a stock motor with all stock parts. Beats me.

The O2's are in the stock location of the manifold collector. I talked to Painless this morning, they are thinking it is probably the ground. I have used Painless harnesses before and have not had this issue. Granted I did not do this harness install.

[gofastwclass]

Granted I did not do this harness install.

That could be your entire problem. I've seen melted wires against headers and pinched or cut wires cause odd or intermittent problems.

Good luck.

[POWERZONE]

That could be your entire problem. I've seen melted wires against headers and pinched or cut wires cause odd or intermittent problems.

Good luck.

I am waist deep now. lol

[cesar]

Sounds like a hassle. Especially when it could be an issue from painless lol.

[XTR PRF CRS]

Firts... what model and year is you ECM? and what is the painless part number that wiring you use?