Odd "Misfire"? on 2013 Yukon Denali

[Bextreme04]

I need to talk to my tuner again, he discussed that with me, and my recollection was that he "turned it off". I never run E85, too difficult to get and the 21 gallons with 11.5 mpg on premium sucks bad enough already for frequent fill-ups, especially only a few stations that carry E85 in the area. I changed the gas cap for a black one and haven't given ethanol a second thought in a good while now. The log did not show any knock, and timing didn't seem to be out of line from what I could tell, not being any kind of expert. But I'll go back and check the ethanol percent shown, and I'm going to re-log the issue to send to my tuner and see what he can see from it.

I know there are a ton of stations in the DFW area, but because gas is so much cheaper for you guys in general, it really is only helpful when towing or very hot. My L9H swap LOVES E85 when towing. It actually gets about the same mileage with E85 as it does with regular gas, and the compression is high enough on the LS3 based truck engine that it really needs premium when towing, so the E85 is about 1/2 the cost of the equivalent gas I would need to run. I just made a run down to California(ewwwww) a few weeks ago in it to tow back my brother in laws enclosed car trailer with his '67 C10 chassis in it. 91 Octane was over $7/gal the whole way down I-5 corridor, but I was able to get E-85 for between $2.99-3.50/gal. I got 13-15mpg from Oregon to LA area with no trailer. Averaged 8mpg on the way back with the loaded trailer. My BIL has a Ram Rebel and he ended up spending over $1000 in gas for the whole trip. It cost me $240 to go from Oregon to LA and $400 to head back.

I had issues with the 'virtual' flex fuel sensor before I did the swap from the 5.3 to the 6.2 and it was reading 50-60% ethanol content on regular pump gas. This was obviously making it run pig rich and causing all kinds of issues, so I also just turned it off until I could get an actual sensor installed. DSX tuning makes a plug and play kit for the sensor that just involved disconnecting the fuel line at the rail, plugging int the sensor in-line, then connecting the provided wiring harness between the drivers side coil harness and running a single wire to the ECM. They have a wire with the correct terminal on it already and you just push it into the right slot on the PCM connector... done.
https://dsxtuning.com/products/dsx-flex-fuel-kit-for-2006-2009-trailblazer-ss?variant=55854380235
Then you can just turn the setting in the tune from 'virtual' to 'sensor' and it is ready to go. You actually have at least 10% ethanol in your regular pump gas, which is enough to throw off the stoichiometric ratio by almost a full point and messes with your timing as well.

 

[Bextreme04]

I need to talk to my tuner again, he discussed that with me, and my recollection was that he "turned it off". I never run E85, too difficult to get and the 21 gallons with 11.5 mpg on premium sucks bad enough already for frequent fill-ups, especially only a few stations that carry E85 in the area. I changed the gas cap for a black one and haven't given ethanol a second thought in a good while now. The log did not show any knock, and timing didn't seem to be out of line from what I could tell, not being any kind of expert. But I'll go back and check the ethanol percent shown, and I'm going to re-log the issue to send to my tuner and see what he can see from it.

Actually, now that I looked.... you have a ton of stations around you that have flex fuel and blender pumps. You actually get BETTER fuel mileage with up to 30-40% ethanol content than with straight gas. We only have 4 E85 stations in the entire state of Oregon and because there aren't very many the cost is not very different from regular 87. I would kill to have blender pumps like that within easy driving range. I would at least call or drive by the place and see what the price difference is. I've seen people post pics from the DFW area with E85 or blended prices below $2/gal... so i'm surprised to hear you say it isn't worth it.

Here's the Department of Energy website that lists E85 or blender pump locations: https://afdc.energy.gov/fuels/ethanol-locations#/find/nearest?fuel=E85

Here's a screenshot of how many E85 stations are in the greater DFW area, with one located in Grand Prairie;

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[Hunter79764]

I live at that dot for Grand Prairie, right in between Dallas and Ft Worth. We go about as far as the center of Arlington pretty often, south to the main highway along the bottom often as well, rarely north at all, and east is the ghetto where I don't want my family going if they can help it... The one station in the center between Arlington, Irving, GP and Euless is honestly in the middle of nowhere about 15 minutes away, and each of the others are 20-25 minutes most of the time, so if we have to use a gallon of gas each way to get to the station, it really is a pain to mess with. On a larger tank, I think it might be worth it, but we don't usually tow with this one, it just has a lot of minivan duty in all reality. What sucks is that the map looks pretty similar for Walmarts, Home Depot locations, and a few others. For being dead in the middle of a huge metropolitan area, we are pretty often dead in the middle of nowhere, relatively speaking.

My wife actually learned to drive in a conversion van, and drove that and a full size station wagon until she was 20. She wanted a conversion van more than a Suburban initially when we had , but I didn't want to work on one and insisted on the SUV's. 15 years later, I've worked on the vans a little bit, and I think she won me over. They aren't as bad as I expected, as long as I don't have to swap engines.

No updates, been busy with too much else. But I've got a new ground cable to install one way or another, and I'll re-record a log to send to my tuner.

 

[bucket]

Lol, it's pretty nice to pull an intake manifold while sitting on the padded floor and both footwells make good parts/tool trays.

 

[Hunter79764]

Lol, it's pretty nice to pull an intake manifold while sitting on the padded floor and both footwells make good parts/tool trays.

That's where I realize I was wrong. I didn't know the doghouse was as big or as useful as it is. I also replaced a heater core on a Kodiak in a couple of hours, did a water pump on an express in 25 minutes in a hotel parking lot (minus fill time), and have generally grown to like the seating position and view of practically sitting on top of the front axle...

I don't think she will go for a Duramax ambulance van though, even though it seems tempting...

 

[DoubleDingo]

Lol, it's pretty nice to pull an intake manifold while sitting on the padded floor and both footwells make good parts/tool trays.

When I first read this I imagined the engine was out and bolted to a stand and you had a padded floor in the shop. I read it again this morning and realized you were describing being inside the van

 

[DoubleDingo]

That's where I realize I was wrong. I didn't know the doghouse was as big or as useful as it is. I also replaced a heater core on a Kodiak in a couple of hours, did a water pump on an express in 25 minutes in a hotel parking lot (minus fill time), and have generally grown to like the seating position and view of practically sitting on top of the front axle...

I don't think she will go for a Duramax ambulance van though, even though it seems tempting...

Buy it first and then have her drive it

 

[bucket]

That's where I realize I was wrong. I didn't know the doghouse was as big or as useful as it is. I also replaced a heater core on a Kodiak in a couple of hours, did a water pump on an express in 25 minutes in a hotel parking lot (minus fill time), and have generally grown to like the seating position and view of practically sitting on top of the front axle...

I don't think she will go for a Duramax ambulance van though, even though it seems tempting...

I've never minded working on the GM vans. In many ways they are easier to work on than a truck. Truth be told, I actually like the '71-'95/'96 G-vans better (they are just more "me"), but the '96-current vans are far superior in basically every way, including ease of maintenance.

 

[Hunter79764]

I think my grandpa's '78 GMC motorhome scared me more than anything. It had the full interior stuff that made the doghouse a pain to remove, and when he replaced the 400 after 25 years of heavy use, it was quite the operation with the core support chopped out, the whole front end removed, and if I recall, he had to carefully lift the engine, remove motor mounts, then drop it back onto the frame just to have enough room to get his cherry picker in there to pull it out the front. So I just thought "Screw that, I'll keep a real hood, thanks." But working on the wife's '13, 5 minutes in and I'm straining my back and cutting my hands because I can't reach everywhere I need to reach. My 01 and 04 are MUCH better in those regards.

 

[Hunter79764]

Victory, -ish. Replaced the negative cable that was corroded, no change but it needed to be done anyway. Dad asked about spark plugs and if maybe they were fouled or something, I hadn't pulled them yet, so went ahead and checked #1. The tip was trashed... #2, also trashed. These were Delco Iridiums with 10-15k. I had 2 new ones in my stash, so I put them in and instant improvement (not fixed, but knew it was the right road). Bought a new set, Dad insisted on a set of wires, and just to make sure, I put a set of the high power coils I had in my stash as well, and with all of that installed, it ran great again.
But the next question is, why did my plugs fail that quickly? It is very possible my wires were not making good connection, they seemed to come off much easier than the new ones went on, both at the plug and the coil. But all 8 doing the same thing at roughly the same time (the issue started, got worse over the course of a week or so, then stayed the same after). I haven't noticed excessive oil burning, but now that it is running better, I think I might have some pinging at high RPM WOT. More to nail down, but at least it is back to normal for the moment.

 

[DoubleDingo]

Not saying you buy bad fuel, but I wonder if fuel may have caused them to go bad early? Or, just bad construction?

 

[Hunter79764]

My wife is pretty consistent with Costco premium gas, which is Top Tier certified. And to clarify, premium is required for the 6.2. I asked my tuner if I should be running different plugs, and I'll do a datalog and see if he has any ideas otherwise.

 

[DoubleDingo]

My wife is pretty consistent with Costco premium gas, which is Top Tier certified. And to clarify, premium is required for the 6.2. I asked my tuner if I should be running different plugs, and I'll do a datalog and see if he has any ideas otherwise.

Top Tier is the way to go.

 

[DoubleDingo]

My wife is pretty consistent with Costco premium gas, which is Top Tier certified. And to clarify, premium is required for the 6.2. I asked my tuner if I should be running different plugs, and I'll do a datalog and see if he has any ideas otherwise.

When we drove to Texas in 2018 for Christmas, my Forester kept getting misfire codes, but it never dropped in performance. Of course we couldn't be selective on where to get fuel during that trip and I think we got some bad gas at a couple stations. Once we got home and back on top tier exclusively the codes never resurfaced. The Forester also requires premium because of the turbo.

 

[Bextreme04]

Victory, -ish. Replaced the negative cable that was corroded, no change but it needed to be done anyway. Dad asked about spark plugs and if maybe they were fouled or something, I hadn't pulled them yet, so went ahead and checked #1. The tip was trashed... #2, also trashed. These were Delco Iridiums with 10-15k. I had 2 new ones in my stash, so I put them in and instant improvement (not fixed, but knew it was the right road). Bought a new set, Dad insisted on a set of wires, and just to make sure, I put a set of the high power coils I had in my stash as well, and with all of that installed, it ran great again.
But the next question is, why did my plugs fail that quickly? It is very possible my wires were not making good connection, they seemed to come off much easier than the new ones went on, both at the plug and the coil. But all 8 doing the same thing at roughly the same time (the issue started, got worse over the course of a week or so, then stayed the same after). I haven't noticed excessive oil burning, but now that it is running better, I think I might have some pinging at high RPM WOT. More to nail down, but at least it is back to normal for the moment.

Where did you get the plugs from? Which Delco plug did you use? I had 41-162's in my 5.3 and they would need replacing every 50k miles or so and also had occasional misfire issues. It's getting hard to find genuine ones and they are often just ripoff chinesium. I put in a set of NGK TR-5's from the local parts store in mine when I rebuilt it and have ~30,000 miles on them now still running perfect. They are only ~$3/ea and are supposedly good for 30-60k miles.