2008 Yukon Denali, 135k miles, part 2!!

[Da90]

I wonder if they would affect the O2 readings?

I’m not sure. I used them when I deleted the cats off my old truck. I was hoping they spaced the o2 sensors far enough away to where it wouldn’t throw a code. It didn’t work. That being said they should work for your application.


Sent from my iPhone using Tapatalk Pro

 

[tgui]

It took 6 hours but I finally got my cat & muffler in. I have a couple very small leaks that I'll work on later. They're minor.

Too lazy for jack stands today.

Out! I had to cut the pipe right before the muffler to get it all out.

Muffler comparison. It was installed the other direction.

Stock muffler starting to rust. This help my excuse to my wife why I'm doing all this.

I used the stock flange and a 3.5'' slip joint to mount the vibrant cat. I want to be able to use any future exhaust easily. I dont exactly stack dimes but I can make things stick with my harbor freight flex core welder. High temp paint to slow down rust.

I used some nice clamps to cut down on the welding. Plus the magnaflow 3.5'' ID was a bit sloppy with the stock pipe when thinking about welding.

Vids below. The magnaflow plus cat takes out the raspy sounds and makes for a very low rumble. You won't hear it on phones or cheap speakers. It comes through on my home theater. I'll be interested in how it all breaks in over a month.

ALSO!! The cat has killed the smells! Thank god!

ALSO #2!! No drone on the highway!

First test with some leaks I have since fixed.

Warm start.

Revving

 

[tgui]

First, why aren't my forum hosted pictures showing? I guess I'll stick to imgur.

Second, the drivers header O2 is still hitting when accelerating. I did research and see that GMT900 trucks have TONS of issues with the stock motor mounts. They're fluid filled and while they work well to stop vibrations, they are too weak for our engines. The drivers side rips and the passengers side gets crushed.


Here is my 1 year old replacement drivers mount. Its already torn.

So I can continue to dent and make more room for the sensor or I can tackle bad mounts (again) and stop the engine from moving as much.


So I got these on order. Poly mounts. I already have engine vibration in the cabin so I think I'll be able to live with these more solid ones.

 

[HiHoeSilver]

First, why aren't my forum hosted pictures showing? I guess I'll stick to imgur.

Second, the drivers header O2 is still hitting when accelerating. I did research and see that GMT900 trucks have TONS of issues with the stock motor mounts. They're fluid filled and while they work well to stop vibrations, they are too weak for our engines. The drivers side rips and the passengers side gets crushed.


Here is my 1 year old replacement drivers mount. Its already torn.

So I can continue to dent and make more room for the sensor or I can tackle bad mounts (again) and stop the engine from moving as much.


So I got these on order. Poly mounts. I already have engine vibration in the cabin so I think I'll be able to live with these more solid ones.

I haven't seen anything about those mounts. Post your experience in the nnbs broken motor mount thread, for sure. I know the current solution is the non hydraulic hummer mounts.

 

[tgui]

I haven't seen anything about those mounts. Post your experience in the nnbs broken motor mount thread, for sure. I know the current solution is the non hydraulic hummer mounts.

I saw those posts about the hummer mounts. Those might transmit a little less vibrations than what I'm getting. I'll post when these are installed.

 

[tgui]

Got em. Damn beefy. I'll have to carve out some time next week to install.

 

[randeez]

Mine are still sitting here on the bench waiting lol, you'll prob have them on before I do mine. Let us know how the feel. I dont see how they wouldn't transmit a little more vibrations but the trade off being the engine not rotating all over the place banging headers against everything would be worth it.

Was probably going to pull headers back out and wrap just to cut down on some of the underhood temp while I installed them...never ending "it's on the list"

 

[tgui]

Wife got in an accident (and is ok) so her car is in the shop and needs to use my other car.... so no mount installation

I did get another badge for the Yukon for under the STi sticker....

 

[tgui]

Fluid is leaking from the 1 year old mount. Time to get cracking.

 

[tgui]

I got a wideband sensor.

 

[swathdiver]

I got a wideband sensor.

What's it for? How do you use it?

 

[tgui]

What's it for? How do you use it?

It measure the air fuel ratio. This one is very sensitive.

When you change things like headers, intakes, cam, etc you change the VE (volumetric efficiency) of the engine, how well it breathes. When it breathes better you gotta add more fuel, but you cant do that well without something like this sensor.

My Yukon idles like crap now with my headers and exhaust because of the changed VE. Too rich you can even kill catalytic converters. Finally I can dial things in.

Ohh, and you can make good amounts of HP too ;-) I had one on my subaru and let me dial in a shit-ton of power.

I can tie this one into my HP Tuners software

 

[swathdiver]

It measure the air fuel ratio. This one is very sensitive.

When you change things like headers, intakes, cam, etc you change the VE (volumetric efficiency) of the engine, how well it breathes. When it breathes better you gotta add more fuel, but you cant do that well without something like this sensor.

My Yukon idles like crap now with my headers and exhaust because of the changed VE. Too rich you can even kill catalytic converters. Finally I can dial things in.

Ohh, and you can make good amounts of HP too ;-) I had one on my subaru and let me dial in a shit-ton of power.

I can tie this one into my HP Tuners software

Ok, I gather then it allows more precise tuning than the E38. The ECM shows the AFR in a different way, mine is normally 1:1 but at WOT it might go to .9:1 or .8:1 with the BB tune. Is the Mass Air Sensor not able to adjust enough until the maps are reprogrammed?

 

[HiHoeSilver]

 

[swathdiver]

View attachment 205123

Me too!

 

[tgui]

Ok, I gather then it allows more precise tuning than the E38. The ECM shows the AFR in a different way, mine is normally 1:1 but at WOT it might go to .9:1 or .8:1 with the BB tune. Is the Mass Air Sensor not able to adjust enough until the maps are reprogrammed?

Your measurements are in lambda. 1:1 is stoic which is ~14.7:1 gas AFR.

The stock O2 sensors are narrow band, can only read a narrow range of AFRs just outside of stoic. They're good for low load engine use where gas mileage is cared about. Outside this is PE mode, power enrich where you're flooring it. Stock O2 sensors arent used here. There is GM from factory calculated VE table that allows for quick RPM/Load lookup for how much the injectors are squirting in.

Sooo, when you change the engine VE with headers you need to update the base VE table and measure (much more accurately than stock sensors can) the near stoic AFRs. THEN you use the wideband when flooring it to measure things around 12.5:1 which you cant do with the stock narrow band O2 sensors.

MAF is only used for low load outside of PE mode driving.

 

[swathdiver]

Your measurements are in lambda. 1:1 is stoic which is ~14.7:1 gas AFR.

The stock O2 sensors are narrow band, can only read a narrow range of AFRs just outside of stoic. They're good for low load engine use where gas mileage is cared about. Outside this is PE mode, power enrich where you're flooring it. Stock O2 sensors arent used here. There is GM from factory calculated VE table that allows for quick RPM/Load lookup for how much the injectors are squirting in.

Sooo, when you change the engine VE with headers you need to update the base VE table and measure (much more accurately than stock sensors can) the near stoic AFRs. THEN you use the wideband when flooring it to measure things around 12.5:1 which you cant do with the stock narrow band O2 sensors.

MAF is only used for low load outside of PE mode driving.

Ok, I mostly understand what you're saying. I just don't remember doing this with our Buicks when we added 300+ horsepower to them. Maybe I've just forgotten.

 

[tgui]

I had an hour. Drivers header out. Uuhhggg my to-do list just got longer.

- header denting for clearance
- engine mounts
- trans lines all need to be replaced
- front shocks are dead
- wideband install

155k miles, no surprises though

Easier the 2nd time. Still annoying.

 

[tgui]

Drivers mount in! I also took some time to hammer more space for the drivers O2 header that was hitting the body. I probably dont need to since these engine mounts will keep the engine still.

Out and then leaked fluid all over the floor. Thanks gm!

Trans supported then 2x4 jacked on the back of the oil pan. It's cast aluminum and braced there.

After. No damage.

AFR mount in!

Thanks for leaking all over my floor like a rubber fruit gusher. Remember those snacks?! ;-)

 

[08grey]

Need more info on Mount please.

Sent from my SM-G950U using Tapatalk