Useless Information

[swathdiver]

It was time to weigh the truck with the new tires. Old tires were KO2s in Load Range C, in the stock size. New tires are P-Metric Michelin Defenders.

Last trip to the scales after the KO2s were put on was 5900 pounds, 3040 on the steer axle, 2860 on the drive axle. That was right in line with the door sticker by 1 pound.

This time she came in a 5860, 3020 on the steer axle and 2840 on the drive axle. That would be 10 pounds a tire difference.

I took out all the junk from the center console that wasn't there when I first weighed it and all the emergency supplies out back too!

Wife took the truck out and had the windows re-tinted. No more purple interior! The next morning the ignition clicked when we went to start it. Another try and she fired right up. Alternator was at full power the whole time to the scales and back so I figured the tint company let the battery drain down. Got in the truck later and the HVAC controller was reset to 74 degrees, that means it lost power. Leaving Grandma's it was 74 degrees again. Christmas afternoon I put a few turns on the positive battery terminal. Hmm...

Start up State of Charge and State of Charge was 70%. The battery is a year old on Christmas Day. I would think it should be higher. Well, when the lights come down I'll get my extension cords back and can put it on the Battery Tender.

On the To Do List:

Plugs and Wires
Coolant Flush
Intake Gaskets
Door Moldings

I have a hankerin' for 3.73 gears...

 

[swathdiver]

Hired a neighborhood kid to help change the plugs and wires in the truck today. Had a rough morning and was pretty weak. Was going to also do the intake gaskets but that would have required more input from me than I was capable of.

Anyhow, we finally got #8 replaced and when we fired it up to check everything out there was an awful racket from the passenger side. Shut down, cooled off and pulled the wires and then the plugs and number 4 was loose. Fixed that, checked the others and it idled better than before.

Was revving the motor in park, had the Tech-2 fired up looking at the misfire counter and cylinders 4 and 7 would occasionally each post 2 misfires when coming off the throttle during a particularly aggressive revving of the engine. Put a kid in the driver's seat and watched the Tech-2 again, yep, coming OFF the gas from full power, high rpms, we would get an occasional misfire count of 2 for cylinder 4 and 7. I think cylinder 3 once but maybe my eyes were deceiving me!

To me, that says the plugs are fine, the wires are fine but maybe the lifters or valvetrain has a wee bit of play in it. There's no knock or ping in those cylinders when that happens, no timing is pulled back because of it either. Thoughts?

This set of plugs and wires had been in the truck for almost four years for 44,316 miles and 1496 engine hours.

The old wires ohmed out between 794 and 835 for an average of 800 and the plugs were either gapped to .041 or .042 save for the old 41-110 in cylinder 8, which had a few thousand more miles on it and was .043".

Driving around town looking at Christmas lights, beating on it today for 24 miles and the mileage is still 14.8 mpgs. Still chasing those wonky negative fuel trims.

Happy New Year Fellas!

 

[iamdub]

Hired a neighborhood kid to help change the plugs and wires in the truck today. Had a rough morning and was pretty weak. Was going to also do the intake gaskets but that would have required more input from me than I was capable of.

Anyhow, we finally got #8 replaced and when we fired it up to check everything out there was an awful racket from the passenger side. Shut down, cooled off and pulled the wires and then the plugs and number 4 was loose. Fixed that, checked the others and it idled better than before.

Was revving the motor in park, had the Tech-2 fired up looking at the misfire counter and cylinders 4 and 7 would occasionally each post 2 misfires when coming off the throttle during a particularly aggressive revving of the engine. Put a kid in the driver's seat and watched the Tech-2 again, yep, coming OFF the gas from full power, high rpms, we would get an occasional misfire count of 2 for cylinder 4 and 7. I think cylinder 3 once but maybe my eyes were deceiving me!

To me, that says the plugs are fine, the wires are fine but maybe the lifters or valvetrain has a wee bit of play in it. There's no knock or ping in those cylinders when that happens, no timing is pulled back because of it either. Thoughts?

This set of plugs and wires had been in the truck for almost four years for 44,316 miles and 1496 engine hours.

The old wires ohmed out between 794 and 835 for an average of 800 and the plugs were either gapped to .041 or .042 save for the old 41-110 in cylinder 8, which had a few thousand more miles on it and was .043".

Driving around town looking at Christmas lights, beating on it today for 24 miles and the mileage is still 14.8 mpgs. Still chasing those wonky negative fuel trims.

Happy New Year Fellas!

Injectors?

I guessed that because it's on the decel/throttle closing. The PCM lengthens the pulse width under load and shortens it off load. Maybe those injectors are "closing too much" or are open too much in the first place? They're just solenoids and maybe they're sloppy from normal wear from age? Perhaps they're too sloppy in both directions and, when commanded to open, they're passing a little too much fuel so the PCM has to keep trimming back the fuel?

 

[George B]

As long as it doesn’t misfire on acceleration what does it matter?

 

[swathdiver]

Injectors?

I guessed that because it's on the decel/throttle closing. The PCM lengthens the pulse width under load and shortens it off load. Maybe those injectors are "closing too much" or are open too much in the first place? They're just solenoids and maybe they're sloppy from normal wear from age? Perhaps they're too sloppy in both directions and, when commanded to open, they're passing a little too much fuel so the PCM has to keep trimming back the fuel?

Certainly possible at 167K miles! I've been chasing high negative fuel trims for years. Hope to get the intake gaskets changed out soon to eliminate them from the list of possibilities.

As long as it doesn’t misfire on acceleration what does it matter?

I don't know, does it?

 

[scruffy]

Yes,fellas-the Lucas formula for ethanol fuel vehicles works great for me (2012 6.2L AWD Denali) until the weather gets wonky on the cold end here on L.I. New York. My dealer says what I've verified through experience. The computer and the fuel blending don't mix, and I use either Flex in the warm weather (nice power jump, terrible mileage, worse in the cold) or at least 91 octanes in the winter.

 

[swathdiver]

Yes,fellas-the Lucas formula for ethanol fuel vehicles works great for me (2012 6.2L AWD Denali) until the weather gets wonky on the cold end here on L.I. New York. My dealer says what I've verified through experience. The computer and the fuel blending don't mix, and I use either Flex in the warm weather (nice power jump, terrible mileage, worse in the cold) or at least 91 octanes in the winter.

I reckon you and the dealer are indeed correct! Thinking about adding the actual sensor later on this year or next after some other projects get done.

 

[George B]

Certainly possible at 167K miles! I've been chasing high negative fuel trims for years. Hope to get the intake gaskets changed out soon to eliminate them from the list of possibilities.


I don't know, does it?

I don’t know. I was just posing the question. I see several dead end threads on the internet where guys notice this but nobody pins down any reason or solution.
I am wondering if the throttle closing and the fuel cutoff is part of it.

 

[swathdiver]

Fun with the Tech-2. After seeing misfires and knock retard on my truck, Julia wanted to see if the Sierra did the same thing. So we added a bottle of Lucas Oil Octane Booster to each truck and made some runs.

The Yukon had misfires on cylinders 4,5 and 7 this time, only two and only at the end of the run as we lifted off the throttle or while revving the engine out of gear. There was a degree of knock or two at the top of 1st gear, cylinders 2 and 3.

The Sierra had zero misfires and only recorded a knock at launch. Plenty of Torque Management in that presumably stock tune. Almost none in the Yukon!

For the Yukon, we recorded a Snapshot of the Engine Torque in the Transmission Section. Playing it back at my desk, I was able to plot the motor's torque at certain RPMs and throttle percentage, which WOT seems to be 98%. From that data it was easy to calculate horsepower and then make a quick graph.



These numbers include both first and second gear, just plotted the numbers in RPM order, 305 Horsepower @ 5,655 RPMs and 334 Foot Pounds of Torque @3,949 RPMs.

It was getting late so we'll do this with the Sierra another night soon. LTFTs on the Yukon were negative as usual and ZERO on the Sierra as they should be. Some time ago we confirmed my long held suspicions that the intake gaskets are leaking. They are on the calendar to get switched out in about three weeks. Hopefully the intake is not warped.

Have to find a section, if it exists, where Engine Load and Torque can be recorded together in the Tech-2.

One of the reasons for collecting this data is for another spreadsheet I've been working on, calculating the Torque in Foot Pounds a the Differential and Force in Newtons of both trucks and a 6.0 L96. The 6.2 motor blows the 6.0 away unless it runs 4.10 gears, then it gets closer. The LC9 using SAE Net figures only equals the tractive effort of the 6.0 when 4.33 gears are used. I'll post that up when done.

In the above graph, the RPMs are from the Snapshot during playback. Not sure how to show that portion of the graph in whole numbers, every 1000 rpms. It would change the shape of the curve I think.

It would be cool to see how your motors graph out! Fire up them Tech-2s!

 

[Tonyrodz]

Fun with the Tech-2. After seeing misfires and knock retard on my truck, Julia wanted to see if the Sierra did the same thing. So we added a bottle of Lucas Oil Octane Booster to each truck and made some runs.

The Yukon had misfires on cylinders 4,5 and 7 this time, only two and only at the end of the run as we lifted off the throttle or while revving the engine out of gear. There was a degree of knock or two at the top of 1st gear, cylinders 2 and 3.

The Sierra had zero misfires and only recorded a knock at launch. Plenty of Torque Management in that presumably stock tune. Almost none in the Yukon!

For the Yukon, we recorded a Snapshot of the Engine Torque in the Induction Section. Playing it back at my desk, I was able to plot the motor's torque at certain RPMs and throttle percentage, which WOT seems to be 98%. From that data it was easy to calculate horsepower and then make a quick graph.

View attachment 359711

These numbers include both first and second gear, just plotted the numbers in RPM order, 305 Horsepower @ 5,655 RPMs and 334 Foot Pounds of Torque @3,949 RPMs.

It was getting late so we'll do this with the Sierra another night soon. LTFTs on the Yukon were negative as usual and ZERO on the Sierra as they should be. Some time ago we confirmed my long held suspicions that the intake gaskets are leaking. They are on the calendar to get switched out in about three weeks. Hopefully the intake is not warped.

Have to find a section, if it exists, where Engine Load and Torque can be recorded together in the Tech-2.

One of the reasons for collecting this data is for another spreadsheet I've been working on, calculating the Torque in Foot Pounds a the Differential and Force in Newtons of both trucks and a 6.0 L96. The 6.2 motor blows the 6.0 away unless it runs 4.10 gears, then it gets closer. The LC9 using SAE Net figures only equals the tractive effort of the 6.0 when 4.33 gears are used. I'll post that up when done.

In the above graph, the RPMs are from the Snapshot during playback. Not sure how to show that portion of the graph in whole numbers, every 1000 rpms. It would change the shape of the curve I think.

It would be cool to see how your motors graph out! Fire up them Tech-2s!

Why do you think you were getting the misfires after adding the additive to the oil James?