Chasing a rough idle?

[2009TahoeLT]

Anything else I can do or check in the meantime?

 

[2009TahoeLT]

Found another evap leak at the charcoal canister. Fixed that. No changes. O2 sensor readings look ok. Still adding fuel and misfiring. All cylinders misfire at 1100 rpm except for cylinder 6

 

[swathdiver]

Ok so my 2009 Tahoe 5.3 has been running a bit rough/choppy.

...I’ve replaced all plugs, wires. Replaced intake manifold gasket. Replaced purge valve. Fuel pump was replaced. Cleaned maf.

What plugs and wires did you use?

Did you confirm the gap on each of the plugs?

Are you CERTAIN that the injector connectors are on the correct injector? Did you check it three times? BTDT.

Same for the plug wires.

Is your brake booster hose connected to the back of the intake? Are the PCV hoses that go into the intake sealed tight?

Have you checked the intake gaskets for leaks since you installed the new ones?

If you've done all of these things, pull the plugs and inspect them. What do they look like?

Are all cylinders misfiring on the scan tool?

 

[rdezs]

250,000 mi on it.... I'd want to take a look at that timing chain. Might have jumped a tooth. Then might as well replace it and the oil pump while you're in there.

Before doing that I'd want to do a compression check and a leak down test.

Keep in mind a lot of times the camshaft position sensor does not throw a code. If it was off a tooth, the ECM would be all over the place trying to make it run and throwing codes for misfires and whatever.

 

[2009TahoeLT]

What plugs and wires did you use?

Did you confirm the gap on each of the plugs?

Are you CERTAIN that the injector connectors are on the correct injector? Did you check it three times? BTDT.

Same for the plug wires.

Is your brake booster hose connected to the back of the intake? Are the PCV hoses that go into the intake sealed tight?

Have you checked the intake gaskets for leaks since you installed the new ones?

If you've done all of these things, pull the plugs and inspect them. What do they look like?

Are all cylinders misfiring on the scan tool?

Copper ac delco plugs, ac delco wires. Gap was confirmed before install. I’m not 100 percent sure on injector connectors tbh but could be switched somewhere. I don’t believe so though. Plug wires go where needed. Booster hose is connected. No leak with new intake gasket. Also all new intake bolts. Does have a decent exhaust manifold leak but the manifold bolts are rusted very bad. I just pulled the plugs earlier. I’ll attach a picture. All cylinders besides cylinder 6 are misfiring only at 1100-1600 rpm. And not enough to throw a code but can hear the popping from the exhaust exit

 

[2009TahoeLT]

250,000 mi on it.... I'd want to take a look at that timing chain. Might have jumped a tooth. Then might as well replace it and the oil pump while you're in there.

Before doing that I'd want to do a compression check and a leak down test.

Keep in mind a lot of times the camshaft position sensor does not throw a code. If it was off a tooth, the ECM would be all over the place trying to make it run and throwing codes for misfires and whatever.

Yeah it doesn’t throw codes but it’s adding fuel and misfiring on every cylinder but cylinder 6, but only at 1100-1600rpm. I may try and see if my buddy has a compression tester to take a look.

 

[Doubeleive]

if you cant get the 02 out I would maybe try and just unbolt the y-pipe and either get it that way or see if it the misfire is still there wide open with no cats on
maybe even just unbolt the 3rd cat. mine was clogged so we gutted it, it's not monitored so sensor don't care

 

[2009TahoeLT]

if you cant get the 02 out I would maybe try and just unbolt the y-pipe and either get it that way or see if it the misfire is still there wide open with no cats on
maybe even just unbolt the 3rd cat. mine was clogged so we gutted it, it's not monitored so sensor don't care

Y pipe is completely rusted. Bolts will snap without a doubt

 

[Fless]

Did I miss the reason for running copper plugs instead of platinum or iridium?

 

[2009TahoeLT]

Did I miss the reason for running copper plugs instead of platinum or iridium?

My buddy recommended copper as they are better but just have to switch them out more frequently