P1174 2008 Yukon Denali

[02Lightning]

Where do I start? I put NTK front o2 sensors in about a month ago. No problems with the old, just maintenance.

 

[kbuskill]

Where do I start? I put NTK front o2 sensors in about a month ago. No problems with the old, just maintenance.

Check your ethanol percentage with a Tech 2 or an OBD2 adapter and Torque Pro app.

 

[wsteele]

Does the engine idle rough or have any other symptoms (like hard starting) or just the code?

 

[Fless]

And what do your long term and short term fuel trims look like, at idle and at 2000 rpm? Both banks...

 

[91RS]

Replace the oxygen sensors with OEM ones only. Make sure the air filter is good quality (OEM also recommended) or if it is a K&N or similar with oil make sure the oil hasn't coated the MAF. Make sure all the intake duct clamps are tight and the duct isn't rolled. Make sure all the PCV tubes are connected and not broken. Make sure the oil cap and dipstick seals are good. No exhaust leaks. If none of those issues are present and the code still returns with the OEM oxygen sensors (pre cat) then you will likely need injectors (and do NOT buy the cheapo knockoffs on eBay and Rock Auto).

 

[02Lightning]

Check your ethanol percentage with a Tech 2 or an OBD2 adapter and Torque Pro app.

I have the Torque Pro app, I didn't think think vehicle had a flex fuel sensor?

 

[02Lightning]

Does the engine idle rough or have any other symptoms (like hard starting) or just the code?

No other symptoms.

 

[02Lightning]

And what do your long term and short term fuel trims look like, at idle and at 2000 rpm? Both banks...

Not sure of that, I'll have to look and see how to do that on Torque Pro if I even can.

 

[02Lightning]

Replace the oxygen sensors with OEM ones only. Make sure the air filter is good quality (OEM also recommended) or if it is a K&N or similar with oil make sure the oil hasn't coated the MAF. Make sure all the intake duct clamps are tight and the duct isn't rolled. Make sure all the PCV tubes are connected and not broken. Make sure the oil cap and dipstick seals are good. No exhaust leaks. If none of those issues are present and the code still returns with the OEM oxygen sensors (pre cat) then you will likely need injectors (and do NOT buy the cheapo knockoffs on eBay and Rock Auto).

I thought NTK made the sensors for GM? I did valve cover gaskets about a month ago, along with cleaning the MAF, throttle body and replacing the front 02 sensors, I will go thru and recheck my work. I did just find out I have an oil leak, from intake valley tray, so I'm hoping maybe it's caused a vacuum leak? I have parts ordered and on the way for this. I would have thought an engine light would have showed up after a month with new O2 sensors.

 

[02Lightning]

Another thought here, I'm getting ready to pull the intake to change the valley tray gasket because of an oil leak. If I pull all the injectors and swap sides the codes should follow right? If the code stays the same I can eliminate the injectors right?

 

[91RS]

I’ve never heard of NTK. Usually Bosch or Denso makes stuff for GM but just because it’s made by them doesn’t mean it’s the exact same part. Yes, in theory if it’s the injectors it would change banks if you swapped them but I wouldn’t recommend that. You have a high probability of breaking them getting them out of the rail and you will need to buy a seal kit if they don’t break. I just replaced the injectors in my Yukon just because it has 187k miles on it and half of them broke and it’s a 12.

 

[02Lightning]

I’ve never heard of NTK. Usually Bosch or Denso makes stuff for GM but just because it’s made by them doesn’t mean it’s the exact same part. Yes, in theory if it’s the injectors it would change banks if you swapped them but I wouldn’t recommend that. You have a high probability of breaking them getting them out of the rail and you will need to buy a seal kit if they don’t break. I just replaced the injectors in my Yukon just because it has 187k miles on it and half of them broke and it’s a 12.

NTK is the same company that makes NGK spark plugs. Damn, wouldn't think that would break that easy. Just a clip holding them right?

 

[wsteele]

If it is idling smooth, with just the code, I wouldn’t expect it to be a clogged injector, but you never know. While you are replacing the valley metal gasket, swapping from side to side should cause it to move to the other bank if it is injectors.

My Yukon has been persistently miscalculating the Ethanol content percentage. It gets up into the high 30’s, all the while I am pumping 10% or less into the tank.

I haven’t gotten a code from this, but it seems to screw with the open loop mixtures and the L/T trims are screwy. I suspect if it got higher, it would produce a code.

 

[91RS]

The clip isn’t what breaks there is a plastic ring that holds on the upper seal which is what breaks.

 

[Fless]

Don't change so many variables at once; get some data first, then make changes incrementally.

If you need to do the intake, do it, then take fuel trims again and compare them before and after.

If you want to do something before the intake gasket is replaced, document the fuel trims then swap the upstream O2 sensors from side to side to see if the trims/issues follow.

 

[kbuskill]

I have the Torque Pro app, I didn't think think vehicle had a flex fuel sensor?

It doesn't have a physical sensor, it has a virtual sensor so to speak.

It uses the O2 sensors and fuel trim data to calculate the ethanol percentage.

You can set up a custom PID in Torque Pro using these parameters to see your Ethanol percentage...

 

[kbuskill]

Not sure of that, I'll have to look and see how to do that on Torque Pro if I even can.

Torque Pro can definitely look at STFTs and LTFTs.

You may need to set up extra GM PIDs in the settings though, I don't remember.